Table of Contents

Cassini’s Swan Song

From the Desk of Jim Green

News from Space

Meeting Highlights

Spotlight on Education

In Memoriam

Milestones

New and Noteworthy

Calendar

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The Lunar and Planetary Information Bulletin collects, synthesizes, and disseminates current research and findings in the planetary sciences to the research community, science libraries, educators, students, and the public. The Bulletin is dedicated to engaging, exciting, and educating those with a passion for the space sciences while developing future generations of explorers.

The Bulletin welcomes articles dealing with issues related to planetary science and exploration. Of special interest are articles describing web-based research and educational tools, meeting highlights and summaries, and descriptions of space missions. Peer-reviewed research articles, however, are not appropriate for publication in the Bulletin. Suggested topics can be e-mailed to the editors, who will provide guidelines for formatting and content.

Dr. Paul Schenk,

Scientific Editor (schenk@lpi.usra.edu)

Renée Dotson,

Production Editor (rdotson@hou.usra.edu)

Copy deadline for the next issue: August 15, 2017

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Feature Story

On September 15 of this year, the mission of the Cassini orbiter at Saturn will come to its official end. Early that morning, the spacecraft’s radio signal will cease as Cassini enters the giant ringed planet’s atmosphere, and the 2-metric-ton vehicle will undergo “molecular dissociation” (in other words, it will burn up). But that date will signify more than just the destruction of a spacecraft. For the hundreds of engineers, scientists, and officials who have worked for as much as a quarter of a century on this project, it will be the end of a personal journey to Saturn.

The Cassini project officially began in 1990 with solicitations for researchers to participate in it, and many people have joined and left the project since then. The great discoveries of Pioneer and Voyager in 1979–1981 provided a glimpse of the marvels of Saturn, but it is doubtful that anyone working on Cassini prior to its arrival in July 2004 could have anticipated the revolution in our understanding of Saturn and its satellites that this mission has provided. Nor could they have guessed just how much the mission would affect them personally. As Cassini’s radio signal fades out for the last time, there probably won’t be many dry eyes in the house.

With its fuel supply running low, Cassini began its “Grand Finale” on April 26 of this year, beginning the process that will end its 13-year-long tour of the Saturn system. On that day, the spacecraft made the first of its 22 nail-biting passes between the inner edge of the ring system and the cold cloud tops of the planet itself. No spacecraft had ever been inside the rings before, and we did not know for certain how dusty this area would be. It proved to be even less dusty that most models had predicted.

“The region between the rings and Saturn is ‘the big empty,’ apparently,” said Cassini Project Manager Earl Maize of NASA’s Jet Propulsion Laboratory. “Cassini will stay the course, while the scientists work on the mystery of why the dust level is much lower than expected.”

Jubilant Cassini flight controllers react to signals from the spacecraft after its first dive inside the ring system on April 26.

A dustier environment in the gap might have meant the spacecraft’s saucer-shaped main antenna would be needed as a shield during most future dives through the ring plane. Such an orientation would have forced changes to how and when Cassini’s instruments would be able to make observations. Because no spacecraft had ever passed through the region before, Cassini engineers oriented the spacecraft so that its 4-meter-wide (13-foot-wide) antenna pointed in the direction of oncoming ring particles, shielding its delicate instruments as a protective measure during this first dive.

Cassini’s Radio and Plasma Wave Science (RPWS) instrument is one of two science instruments with sensors that poke out from behind the protective shield of the antenna (the other being the magnetometer). RPWS detected the hits of hundreds of ring particles per second when it crossed the ring plane just outside of Saturn’s main rings, but it only detected a few pings on April 26.

“It was a bit disorienting — we weren’t hearing what we expected to hear,” said William Kurth, RPWS team lead at the University of Iowa, Iowa City. “I’ve listened to our data from the first dive several times and I can probably count on my hands the number of dust particle impacts I hear.” The team’s analysis suggests that Cassini only encountered a few particles as it crossed the gap — none larger than those you would find in smoke [about 1 micrometer (0.00004 inches) across].

Diagram of Cassini’s final tour, showing the F-ring and proximal (“Grand Finale”) orbits inside the main ring system.

Mission planners could have opted to end the Cassini mission in a much less dramatic fashion, including having it simply leave the saturnian system. But in order to avoid the (albeit unlikely) possibility of Cassini someday colliding with one of Saturn’s active icy moons, NASA officials chose to safely dispose of the spacecraft in the atmosphere of Saturn. This course will ensure that Cassini cannot contaminate any future studies of habitability and potential life on those moons. And of all the possible options for the end of the mission, the Grand Finale tour presents unique opportunities that the others do not.

“This planned conclusion for Cassini’s journey was far and away the preferred choice for the mission’s scientists,” said Linda Spilker, Cassini project scientist at NASA’s Jet Propulsion Laboratory. After completing seven of the close orbits to be included in its final tour, the results from Cassini have not disappointed.

The Grand Finale is designed to accomplish several things that can only be done by getting “in Saturn’s face.” The close encounters will attempt to determine how massive Saturn is, how its gases are distributed in the interior, and whether it has a solid rocky or metallic core. High-resolution observations are also planned of Saturn’s cloud tops, and several orbits will skim the upper atmosphere to directly sample its composition for the first time. Cassini will also explore the innermost regions of Saturn’s magnetic field, where much of the radiation so dangerous to Jupiter-orbiting vehicles is absorbed by multitudes of tiny ring particles.

Two polar views of two gas giants. At top is a Junocam view of the turbulent north polar region of Jupiter acquired in 2017. At bottom is a Cassini view of Saturn’s north polar region showing hexagonal cloud features and cloud tops; rings are visible in the background at top right.

As for the rings, Cassini will try to sample their composition for the first time and estimate the mass of the ring system. Unknown at present, the total mass of the rings could be as great as that of Mimas, one of Saturn’s seven largest moons. Determining the mass of the rings should help us better understand the origin and, possibly, the age of the ring system. Cassini will continue to broadcast data from all of its instruments as it dives into the atmosphere, sampling atmospheric and magnetic composition and conditions until the spacecraft begins to tumble and contact is lost.

In many ways, the Grand Finale of Cassini’s mission is an entirely new mission to Saturn for a fraction of the cost of starting from scratch. The plan and objectives are very similar and complementary to those of Juno, the spacecraft now orbiting Jupiter to study its cloud structure and interior composition in unprecedented detail, and whose first science results are now coming in (see the related article in the News from Space section of this issue). Detailed comparison of the internal structures of Jupiter and Saturn will now be possible. The data from the seven Grand Finale orbits of Saturn completed so far have not yet been fully analyzed, but it is already clear that the contrast between the polar cloud structures on the two planets could hardly be greater. It now remains for us to return to Uranus or Neptune — or both — to map out those complex planetary systems in detail and attempt to understand how these four very different planets near the edge of our solar system were constructed and evolved.

Cassini acquired numerous high-resolution mosaics of the ring system, including this spectacular three-frame view of 8-kilometer-wide (5-mile-wide) Daphnis disturbing the edges of the Keeler Gap in which it is embedded.

Cassini’s Grand Finale was preceded by the F-ring and proximal phase, which began last October and took Cassini close to the outer edge of the rings for the first time. Spectacular data detailing ring features and the small moons along the edge that help control the distribution of ring particles were obtained. A now-iconic example is the high-resolution view of the tiny moon Daphnis and its close interaction with the Keeler Gap, a 42-kilometer-wide (26-mile-wide) gap in the A ring. Daphnis is a small moon at 8 kilometers (5 miles) across, but its gravity is strong enough to disturb the tiny particles along the edges of the ring that form the narrow Keeler gap. As the moon moves through this gap, wave-like features are created in both the horizontal and vertical planes. Images like this provide scientists with a close-up view of the complicated gravitational interactions between the moons and the rings, as well as the interactions between the ring particles themselves, in the wake of the moon’s passage. Three wave crests of diminishing sizes trail Daphnis in the image shown on the next page. In each subsequent crest, the shape of the wave evolves, as the ring particles within the crests collide with one another. In another of Cassini’s great surprises, much of the disturbed dust and larger particles is deflected up above the plane of the ring by hundreds of meters. This phenomenon was found in other areas along the edges of the “razor-thin” rings but rarely within the main body of the ring [which is actually about 10 meters (32 feet) thick]. These vertical ripples were revealed by the shadows they cast only when the rings are edge on to the Sun.

Saturn has a family of colorful orbiting “regular” spheroidal moons that were discovered before the Space Age began in 1957: from Mimas out to Iapetus and distant Phoebe. Iapetus was well known before arrival as the black and white moon with the greatest contrast in hemispheric brightness observed anywhere in the solar system. Although orbiting Saturn at considerable distance, Cassini was able to get two close encounters with this moon; images showed the complex border between the dark and light terrains, now known to be created by the interaction of sunlight with the icy surface of Iapetus. The biggest surprise was the discovery of an enormous ridge more than 10 kilometers (6 miles) high along its equator, believed to be the remnant of an ancient ring system of Iapetus now deposited on the surface — count that among Cassini’s top 10 discoveries! The other moons were not to be outdone, as they revealed enormous fracture systems, giant impact basins, and their own smiley faces: the now infamous Pac-Man-shaped color and thermal anomalies created by high-energy electrons bombarding and altering the brightness and compaction of the surface.

Perspective view of the great equatorial ridge on Iapetus, probably formed when an ancient Iapetus ring reaccreted onto the surface. The large, partially ice-covered mountain is roughly 32 kilometers (20 miles) across and 6.5 kilometers (4 miles high.

As fascinating as Saturn’s regular moons are, the smaller inner moons [all of which are less than 100 kilometers (62 miles) wide] are full of surprises, with bizarre shapes and surface textures. Atlas and Pan look like flying saucers, but Methone looks like a smooth featureless Easter egg. Helene has channel-like textures caused by the downslope movement of debris. Many of these textures may be related to the unrelenting accumulation of dust from the nearby ring system.

As we approach Cassini’s final plunge, we look back on the spacecraft and its mission. Cassini weighs 2500 kilograms (5560 pounds) without fuel and is roughly the size of a school bus. As of September 15, Cassini will have completed 294 orbits of Saturn since July 2004; more than 127 close encounters with its large moon Titan; and 22 close visits to active Enceladus, including one pass within only 48 kilometers (30 miles) of the surface (now that’s navigational precision!). Cassini will have returned more than 400,000 images and thousands of other datasets of the saturnian system. Its radar will have mapped more than 50% of the surface of haze-covered satellite Titan. The orbiter also delivered the first-ever lander to an object in the outer solar system, the Huygens probe, which landed on Titan in January 2005.

But those are just the dry facts. Behind these numbers lies a treasure of discoveries. Even the short list of Cassini’s discoveries is stunning: river valleys and lakes of liquid hydrocarbons on Titan, both active venting of water ice and vapor from its south pole and a subsurface ocean on Enceladus, etching and discoloration of the icy moons Tethys and Mimas by high-energy-electron bombardment, “mountains” of dust raised above the edges of the rings, “propellers” and clouds of dust within the rings triggered by embedded moonlets and impacting boulders, giant storms on Saturn that flare up every decade or so, and odd hexagonal and cyclonic wind patterns at Saturn’s poles that contrast sharply with the chaotic swirling storms observed on Jupiter by Juno, to name just a few.

Titan’s hydrocarbons seas were a prime target for study during the Cassini tour. The Titan flyby on August 21, 2014, included a segment designed to collect altimetry (or height) data, using the spacecraft’s radar instrument, along a 200-kilometer (120-mile) shore-to-shore track on Kraken Mare, Titan’s largest sea. This synthetic radar image shows the rugged channel-carved shores of Kraken Mare.

In a planetary system so rich in objects and physical processes, it is no wonder that Saturn has proven to be so photogenic. Even from Earth we could appreciate its beauty, but the vistas imaged by Cassini have exceeded even the imagination of artists. Views captured by the spacecraft remind us that one enduring property of the universe is that it is simply beautiful.

But Cassini did not make all these discoveries merely by accident. Cassini is a “Flagship-class” mission, the largest and most expensive of three classes of NASA solar system mission programs. Although expensive, Cassini demonstrated the real value of this class of mission. Cassini carries 12 science instruments that span much of the electromagnetic spectrum. The Saturn system is so rich in objects and physical processes that we were able to explore all these new discoveries in ways that a smaller mission could not have. While the images show us what is out there and what is happening, without the infrared detectors and particle analyzers we would never have known the complex chemistry of the icy particles being ejected from the salty ocean beneath Enceladus’ surface, or how hot the geysers of Enceladus are (well, cold to us, but for an Enceladan, like a Finnish sauna bath!). Because of these findings, Enceladus is now considered a leading candidate for places other than Earth that might be capable of supporting some form of life. Another example of the power of Cassini’s instrument suite is the discoveries made about Titan, the largest moon of Saturn. Because of its hazy atmosphere, it is not possible for humans to view Titan’s surface. With the powerful combination of infrared filters, radar mapping, and a camera on the Huygens lander, we were able to map most of the surface of Titan. In doing so, we found an eroded windswept landscape with dunes composed of organic sand grains, carved by innumerable river channels cut by intermittent organic rains, lakes in the north filled with liquid methane and ethane, and even occasional clouds. These views revealed an alien planetary landscape that appears startlingly similar to Earth. Titan has weather, and climate; the difference is that the atmospheric clouds and rains on Titan are dominated by methane instead of water. Thanks to Cassini’s array of instruments and detectors, we now have a better understanding of the complexity of the rich organic chemistry of Titan’s atmosphere and surface, a natural laboratory for organic development. Much work remains before we can fully understand how this organic chemical system behaves and how it differs from Earth.

Cassini image showing high-altitude clouds in the atmosphere of Titan. These views were acquired with a filter that sees through the opaque haze decks and to the surface, but shows clouds when they do appear.

Before Cassini arrived at Saturn, our expectations were based on the results of the trailblazing Pioneer 11 in 1979 and the spectacular Voyager 1 and 2 encounters in 1980 and 1981. We knew where to look and which objects were most interesting (Saturn, the rings, Titan), yet we were surprised by the complexity and variety of features and processes Cassini observed. Cassini had three advantages over Voyager. Aside from its more powerful set of instruments, Cassini could get much closer to the multitude of objects populating the Saturn system, including that barn-storming grazing pass over the south pole of Enceladus and those cloud-skimming passes above Titan and Saturn. These close encounters not only gave us images that could resolve boulders and small craters and fractures on the surfaces of the moons, but allowed Cassini to measure the detailed gravitational pull of these bodies and investigate their interior mass distribution (whether they have rocky cores, for example), as well as directly measure the composition and mass of particles ejected from Enceladus or escaping from the top of Titan’s atmosphere.

The third advantage is that, as an orbiter rather than a flyby mission, Cassini could stay at Saturn for as long as the fuel and the spacecraft itself held out. Thus, we could watch changes for almost half a “year” on both Titan and Saturn as they went from northern winter to northern summer (one full year in the Saturn system lasts 29.5 Earth years). Cassini monitored giant storms on Saturn, the arrival of spring and summer at the north pole (and autumn and winter at the south), and the emergence of new methane cloud and high-altitude haze patterns on Titan. We could also watch the changing intensity of the geysers on Enceladus as the moon moved closer to and further from Saturn in its orbit.

The huge storm churning through the atmosphere in Saturn’s northern hemisphere overtakes itself as it encircles the planet in this true-color view from the Cassini spacecraft.

Interest remains high in returning to the fabulous Saturn system in the future with spacecraft designed to explore some of these new discoveries in greater detail. Like all mission proposals, these new concepts will have to compete for resources, but some of the more intriguing ideas include descending to the surface of Titan to sample the organic materials on the surface directly, or skimming directly into the Enceladus plumes with more powerful compositional analyzers to search for organic particles. The rings themselves are exquisite natural laboratories in which to study the complex effects of gravity and are worthy of a dedicated mission. Saturn is a miniature planetary system rich in natural phenomena and the Cassini data will keep us busy for decades as we seek to understand all that this mission has revealed.

About the Author:

Dr. Paul Schenk is a staff scientist at the Lunar and Planetary Institute (LPI) in Houston and serves as the science editor for the Lunar and Planetary Information Bulletin. A space-groupie since the days of the Gemini program in the mid 1960s, Schenk’s first formal introduction to planetary sciences was as a NASA Planetary Geology summer intern in 1979 at the Jet Propulsion Laboratory during the Voyager 2 Jupiter encounter. After completing his Ph.D. at Washington University in St. Louis under advisor William B. McKinnon, Schenk came to the LPI in 1991. Schenk’s research at LPI centers on elucidating the geology and topography of the surfaces of the satellites of the outer planets and Vesta, with a particular interest in the unexpectedly rugged topographic relief on Europa and the shapes of impact craters on Europa, Enceladus, and the icy satellites in general. He currently serves as a Co-Investigating Scientist on the New Horizons mission, and a Participating Scientist on the Dawn (at Vesta and Ceres) and Cassini missions.

About the Cover:

Clip from an animation showing Cassini as it prepares to dive between Saturn and its inner ring system in preparation for its final dive into the atmosphere itself early on September 15. All images used with the feature story of this issue are courtesy of NASA/JPL.

From the Desk of Jim Green

NASA’s Solar System Exploration: Saturn According to Cassini

Before Cassini, we had only brief glimpses of the discoveries awaiting us at Saturn. Pioneer 11 and Voyagers 1 and 2 conducted flybys decades ago, taking pictures, measurements, and observations as they zoomed past. These missions shed new light on Saturn’s complicated ring system, discovered new moons and made the first measurements of Saturn’s magnetosphere. But these quick encounters didn’t allow time for more extensive scientific research. Cassini changed all that. It began the first in-depth, up-close study of Saturn and its system of rings and moons in 2004. It became the first spacecraft to orbit Saturn, beginning a mission that yielded troves of new insights over more than a decade. The saturnian system proved to be rich ground for science exploration and discoveries, and in many ways, Cassini’s science findings changed the course of future planetary exploration. By the time Cassini dives into Saturn at the end of its mission, it will have observed the planet for a little less than half of a Saturn year. But it will have also orbited the gas giant 293 times, forever changing our understanding of the Saturn system and yielding tremendous insight for understanding the entire solar system. Cassini has been nothing short of a discovery machine! Cassini’s observations have given us new views of the planet that provided a plethora of iconic images; and some of the groundbreaking discoveries in our relentless search for life in the solar system. Whether revealing that Titan is going through similar cycles as Earth before life evolved, or spying activities of icy plumes on Enceladus, getting up close and personal with Saturn’s rings, and discovering new moons never observed before; Cassini ushered a new age of discoveries in the solar system and is a testament to the hard work and vision of its team.

As every NASA flagship mission has done in the past, Cassini’s road to implementation was a long and winding one. In 1982, the European Science Foundation and the American National Academy of Sciences formed a working group to investigate future cooperative missions. At that time, a suggestion for a paired Saturn Orbiter and Titan Probe as a possible joint mission was brought forward. In 1983, NASA’s Solar System Exploration Committee recommended the same Orbiter and Probe pair as a core NASA project. NASA and the European Space Agency(ESA) performed a joint study of the potential mission from 1984 to 1985. ESA continued with its own study in 1986, while the American astronaut Sally Ride, in her influential 1987 report NASA Leadership and America’s Future in Space, also examined and supported a Saturn mission. In 1988, the Associate Administrator for Space Science and Applications of NASA, Len Fisk, returned to the idea of a joint NASA and ESA mission and worked with his counterpart at ESA, Roger Bonnet, on a NASA/ESA partnership involving a Saturn orbiter (Cassini) and a lander (Huygens) for the moon Titan.

The spacecraft was planned to be the second three-axis stabilized, radioisotope-powered Mariner Mark II, a class of spacecraft developed for missions beyond the orbit of Mars. Cassini would be developed simultaneously with the Comet Rendezvous Asteroid Flyby (CRAF) spacecraft, but budget cuts and project rescope forced NASA to terminate CRAF development to save Cassini. As a result, Cassini became more specialized and the Mariner Mark II series was canceled. This move resulted in deleting the mission’s scan platform to lower the cost of the mission.

Overall, the collaboration with ESA helped Cassini-Huygens survive congressional budget cuts in the United States. Cassini-Huygens came under fire politically in both 1992 and 1994, but NASA successfully advocated and kept the mission alive. The project proceeded politically smoothly after 1994. However, citizens’ groups did attempt to derail its 1997 launch since they had concerns about the potential environmental impact if the launch vehicle exploded on the launch pad in such a way that it would release the plutonium onboard the spacecraft. But it proceeded successfully since simulations showed that the plutonium could be contained in such an explosion.

Since its arrival in 2004, Cassini-Huygens has been studying the planet and its many natural satellites and astounding us with data never before obtained with such detail and clarity. I would like to mention just a few things about this mission that I think puts its accomplishments into the phenomenal category.

Cassini’s decade-long mission made it possible to watch changes in Saturn’s dynamic ring system, study many of the moons in great detail, and watch the planet undergo phenomenal seasonal changes. The spacecraft discovered propeller-like formations, witnessed the possible birth of a new moon, and observed what may be one of the most active, chaotic rings in our solar system (Saturn’s F ring).

The rings from Saturn are truly amazing,but the planet itself offers irresistible and inexhaustible subjects for intense study, and Cassini did not disappoint. Some of the more spectacular of these subjects included lightning on Saturn’s nightside and dayside, neither of which had been imaged before; Saturn’s 30-year storm, which appeared 10 Earth years earlier than usual, allowing the first up-close study of the phenomenon; and imaging of the hexagonal jet stream around Saturn’s north pole, first in the infrared and later in visible wavelengths of light, revealing the remarkable symmetry and stability of this feature.

On October 29, 2006, the Cassini spacecraft was maneuvered into position to observe a bizarre six-sided jet stream encircling the north pole of Saturn near 78° north latitude. Originally discovered and last observed by NASA’s Voyager flybys of the early 1980s, the new views of this polar hexagon immediately prove that this is an unusually long-lived feature on Saturn. Cassini’s infrared instrument began studying Saturn’s northern winter atmosphere by sensing the heat coming from within the planet filtered through the clouds. The hexagon cloud structure was immediately observed. Over time, as Saturn’s north entered spring, Cassini imaged the hexagon in visible wavelengths of light, revealing a stunningly symmetric shape 30,000 kilometers (20,000 miles) across with winds at around 322 kilometers per hour (200 miles per hour). It has been stated that the spinning vortex of Saturn’s north polar storm resembles “a deep red rose of giant proportions.” Measurements have sized the storm’s eye at a staggering 2000 kilometers (1250 miles) across with cloud speeds as fast as 150 meters per second (330 miles per hour). Cassini has also studied Saturn’s auroras, its atmospheric composition, the swelling of its outer atmosphere (the thermosphere), and the still somewhat controversial planet’s rate of rotation (a Saturn day is about 10.5 Earth hours).

After centuries looking at the planet from far, we thought that we had at least observed most if not all of Saturn’s moons. It all began when Christiaan Huygens first observed Titan in 1655. Then Giovanni Cassini discovered Iapetus, Rhea, Dione, and Tethys. Now, centuries later, we have discovered many more. Cassini not only discovered previously unknown moons, but also helped us helped us understand the science behind their formation, their interactions with the rings, and their diversity. Finally, among Saturn’s natural satellites, Cassini found the only known world aside from Earth’s Moon to have a statically charged surface, Hyperion.

Before 2004, we knew very little about Saturn’s moon Titan other than its size and that it had a dense, nitrogen-rich atmosphere. Cassini and Huygens have revealed Titan as never before. We have discovered that Titan has lakes and seas of liquid methane and ethane, several larger than our own Great Lakes, and has an atmospheric cycle and seasons of rain from its hydrocarbon clouds. The mission also provided evidence that Titan has a liquid ocean beneath its surface. The discovery of a global ocean of liquid water adds Titan to the handful of worlds in our solar system that could potentially contain habitable environments.

Huygens’s historic 2005 landing on Titan was the most distant in our solar system to date. Huygens made the first direct measurements of Titan’s lower atmosphere. Data returned by the probe included altitude profiles of the gaseous constituents, isotopic ratios, and trace gases (including organic compounds). Huygens confirmed that carbon and nitrogen are their major constituents. Cassini measurements detected other chemicals in Titan’s atmosphere, including propylene and hydrogen cyanide. The variety of chemicals observed indicates a rich and complex chemistry originating from methane and nitrogen and evolving into complex molecules, eventually forming the smog that surrounds the icy moon. It is believed that methane and ethane rain falls from clouds in Titan’s atmosphere.

In fact, Cassini has demonstrated how Titan’s weather is changing with the seasons and storms have become more common at low latitudes. A huge cloud observed on Titan in September 2010 was quickly followed by extensive changes on the surface. Widespread methane rainfall from the storm is making the surface wet, perhaps even causing flooding in some places. Titan’s geology has also shown that this type of flooding must have occurred extensively in Titan’s past.

But Titan isn’t the only saturnian moon that boasts of a subsurface ocean. Indeed, using Cassini data, scientists have determined that Enceladus has a subsurface ocean beneath its icy crust. Geyser-like jets spew water vapor and ice particles from this underground ocean. The jets shoot out of fractures, which are wider or narrower depending on where Enceladus is in its orbit around Saturn. In fact, after studying specific control points across the surface of Enceladus accumulated over seven years, scientists found a forced physical libration too large to be consistent with Enceladus’s core being rigidly connected to its surface. This implies the presence of a global ocean, rather than a localized polar sea.

We have now identified that the jets are the source of material for Saturn’s E ring. For decades, scientists didn’t know how Enceladus related to Saturn’s E ring. Cassini data confirmed that both the fresh coating on its surface, and icy material in the E ring, originate from the material coming from the vents leading into its global subsurface. The material shoots out at about 400 meters per second (800 miles per hour) and forms huge plumes. Most of the material falls back onto Enceladus, and some escapes into space from Saturn’s vast E ring. The E ring is mostly made of ice droplets, but among them are peculiar nanoparticles. Cassini detected these passing silica nanograins, which can only be generated where liquid water and rock interact at temperatures above 90°C (about 200°F). This points to hydrothermal vents deep beneath Enceladus’ icy shell, not unlike the hydrothermal vents in Earth’s ocean floor.

New Cassini mass spectra data were used to model the ocean water on Enceladus to estimate the acidity or basicity (pH) of its ocean, answering a fundamental question in determining whether Saturn’s icy moon Enceladus could support life. Studies found the ocean to have a very high pH (~11–12) and is salty, containing both sodium chloride (NaCl), as in Earth oceans, as well as sodium carbonate (Na_2CO_3), similar to Earth’s soda lakes. The alkaline pH results from “serpentinization,” and thus a potential source of energy for microbial life on Earth.

Data from the Cassini plasma spectrometer (CAPS) found a strongly negative charge on Saturn’s small moon Hyperion. In fact, this is the first confirmed detection of a charged surface on an object other than the Earth’s Moon. Hyperion’s position between Saturn’s magnetosphere and the solar wind is likely the cause of the surprising electrical charge.

Cassini data helped scientists find evidence that Mimas too may have a subsurface ocean, or at least a football-shaped water-ice core. Data has also shown thin atmospheres around the moons Dione and Rhea. Cassini also solved the centuries-old puzzle about why the moon Iapetus has one snow-white hemisphere, while its other hemisphere is nearly as dark as charcoal. Who knew that dark material falls on Iapetus’s leading side?

As I think about Cassini’s 13 years at Saturn, I am amazed by the scientific impact of this mission. Humanity will look back one day, and determine the role this mission played in our understanding of the origin and evolution of our solar system and its legacy of future missions. So congratulations, Cassini, for forging a clear path for us when we return to the Saturn system and determine if it also harbors life.

— James L. Green, Director, NASA’s Planetary Science Division, May 2017

News from Space

New NASA Radar Technique Finds Lost Lunar Spacecraft

DSS-14 is NASA’s 70-meter (230-foot) antenna located at the Goldstone Deep Space Communications Complex in California. It is known as the “Mars Antenna” as it was first to receive signals from the first spacecraft to closely observe Mars, Mariner 4, on March 18, 1966. Credit: NASA/JPL-Caltech.

Finding derelict spacecraft and space debris in Earth’s orbit can be a technological challenge. Detecting these objects in orbit around Earth’s Moon is even more difficult. Optical telescopes are unable to search for small objects hidden in the bright glare of the Moon. However, a new technological application of interplanetary radar pioneered by scientists at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, has successfully located spacecraft orbiting the Moon — one active, and one dormant. This new technique could assist planners of future Moon missions.

“We have been able to detect NASA’s Lunar Reconnaissance Orbiter [LRO] and the Indian Space Research Organization’s Chandrayaan-1 spacecraft in lunar orbit with groundbased radar,” said Marina Brozovic, a radar scientist at JPL and principal investigator for the test project. “Finding LRO was relatively easy, as we were working with the mission’s navigators and had precise orbit data where it was located. Finding India’s Chandrayaan-1 required a bit more detective work because the last contact with the spacecraft was in August of 2009.”

Add to the mix that the Chandrayaan-1 spacecraft is very small, a cube about 1.5 meters (5 feet) on each side — about half the size of a smart car. Although the interplanetary radar has been used to observe small asteroids several million miles from Earth, researchers were not certain that an object of this size as far away as the Moon could be detected, even with the world’s most powerful radars. Chandrayaan-1 proved the perfect target for demonstrating the capability of this technique.

While they all use microwaves, not all radar transmitters are created equal. The average police radar gun has an operational range of about 1.5 kilometers (roughly 1 mile), while air traffic control radar goes to about 96 kilometers (60 miles). To find a spacecraft 380,000 kilometers (237,000 miles) away, JPL’s team used NASA’s 70-meter (230-foot) antenna at NASA’s Goldstone Deep Space Communications Complex in California to send out a powerful beam of microwaves directed toward the Moon. Then, the radar echos bounced back from lunar orbit were received by the 100-meter (330-foot) Green Bank Telescope in West Virginia.

Finding a derelict spacecraft at lunar distance that has not been tracked for years is tricky because the Moon is riddled with mascons (regions with higher-than-average gravitational pull) that can dramatically affect a spacecraft’s orbit over time, and even cause it to have crashed into the Moon. JPL’s orbital calculations indicated that Chandrayaan-1 is still circling some 200 kilometers (124 miles) above the lunar surface, but it was generally considered “lost.” However, with Chandrayaan-1, the radar team utilized the fact that this spacecraft is in polar orbit around the Moon, so it would always cross above the lunar poles on each orbit. So, on July 2, 2016, the team pointed Goldstone and Green Bank at a location about 160 kilometers (100 miles) above the Moon’s north pole and waited to see if the lost spacecraft crossed the radar beam. Chandrayaan-1 was predicted to complete one orbit around the Moon every two hours and eight minutes. Something that had a radar signature of a small spacecraft did cross the beam twice during four hours of observations, and the timings between detections matched the time it would take Chandrayaan-1 to complete one orbit and return to the same position above the Moon’s pole.

The team used data from the return signal to estimate its velocity and the distance to the target. This information was then used to update the orbital predictions for Chandrayaan-1. “It turns out that we needed to shift the location of Chandrayaan-1 by about 180°, or half a cycle from the old orbital estimates from 2009,” said Ryan Park, the manager of JPL’s Solar System Dynamics group, who delivered the new orbit back to the radar team. “But otherwise, Chandrayaan-1’s orbit still had the shape and alignment that we expected.” Radar echos from the spacecraft were obtained seven more times over three months and are in perfect agreement with the new orbital predictions. Some of the follow-up observations were done with the Arecibo Observatory in Puerto Rico, which has the most powerful astronomical radar system on Earth.

Hunting down LRO and rediscovering Chandrayaan-1 have provided the start for a unique new capability. Working together, the large radar antennas at Goldstone, Arecibo, and Green Bank demonstrated that they can detect and track even small spacecraft in lunar orbit. Groundbased radars could possibly play a part in future robotic and human missions to the Moon, both for a collisional hazard assessment tool and as a safety mechanism for spacecraft that encounter navigation or communication issues.

Detecting Life in the Driest Place on Earth

Chile’s Atacama Desert is the driest non-polar desert on Earth — and a ready analog for Mars’ rugged, arid terrain. Credit: NASA/JPL-Caltech.

Few places are as hostile to life as Chile’s Atacama Desert. It’s the driest place on Earth, and only the hardiest microbes survive there. Its rocky landscape has lain undisturbed for eons, exposed to extreme temperatures and radiation from the Sun. If you can find life here, you might be able to find it in an even harsher environment — like the surface of Mars. That’s why a team of researchers from NASA and several universities visited the Atacama earlier this year. They spent 10 days testing devices that could one day be used to search for signs of life on other worlds. That group included a team from NASA’s Jet Propulsion Laboratory in Pasadena, California, working on a portable chemistry lab called the Chemical Laptop. With just a small water sample, the Laptop can check for amino acids, the organic molecules that are widespread in our solar system and considered the building blocks of all life as we know it. Liquid-based analysis techniques have been shown to be orders of magnitude more sensitive than gas-based methods for the same kinds of samples. But when you scoop up a sample from Mars, the amino acids you’re looking for will be trapped inside of or chemically bonded to minerals.

To break down those bonds, JPL has designed another piece of technology, a subcritical water extractor that would act as the “front end” for the Laptop. This extractor uses water to release the amino acids from a soil sample, leaving them ready to be analyzed by the Chemical Laptop. “These two pieces of technology work together so that we can search for biosignatures in solid samples on rocky or icy worlds,” said Peter Willis of JPL, the project’s principal investigator. “The Atacama served as a proving ground to see how this technology would work on an arid planet like Mars.”

Willis’ team revisited an Atacama site he first went to in 2005. At that time, the extractor he used was manually operated; this time, the team used an automated extractor designed by Florian Kehl, a postdoctoral researcher at JPL. The extractor ingests soil and regolith samples and mixes them with water. Then, it subjects the samples to high pressure and temperature to get the organics out. “At high temperatures, water has the ability to dissolve the organic compounds from the soil,” Kehl said. “Think of a tea bag: In cold water, not much happens. But when you add hot water, the tea releases an entire bouquet of molecules that gives the water a particular flavor, color, and smell.” To remove the amino acids from those minerals, the water has to get much hotter than your ordinary cup of tea: Kehl said the extractor is currently able to reach temperatures as high as 200°C (392°F).

Liquid samples would be more readily available on ocean worlds like Jupiter’s moon Europa, Kehl said. There, the extractor might still be necessary, as amino acids could be bonded to minerals mixed into the ice. They also may be present as part of larger molecules, which the extractor could break into smaller building blocks before analyzing them with the Chemical Laptop. Once the extractor has prepared its samples, the Laptop can do its work.

The Chemical Laptop checks liquid samples for a set of 17 amino acids — what the team refers to as “the Signature 17.” By looking at the types, amounts, and geometries of these amino acids in a sample, it’s possible to infer the presence of life. “All these molecules ‘like’ being in water,” said Fernanda Mora of JPL, the Chemical Laptop’s lead scientist. “They dissolve in water and they don’t evaporate easily, so they’re much easier to detect in water.”

The Laptop mixes liquid samples with a fluorescent dye, which attaches to amino acids and makes it possible to detect them when illuminated by a laser. The sample is then injected onto a separation microchip. A voltage is applied between the two ends of the channel, causing the amino acids to move at different speeds toward the end, where the laser is shining. Amino acids can be identified by how quickly they move through the channel. As the molecules pass through the laser, they emit light that is used to quantify how much of each amino acid is present. “The idea is to automate and miniaturize all the steps you would do manually in a chemistry lab on Earth,” Mora said. “That way, we can do the same analyses on another world simply by sending commands with a computer.”

The near-term goal is to integrate the extractor and Chemical Laptop into a single, automated device. It would be tested during future field campaigns to the Atacama Desert with a team of researchers led by Brian Glass of NASA’s Ames Research Center in Mountain View, California. “These are some of the hardest samples to analyze you can get on the planet,” Mora said of the team’s work in the Atacama. She added that in the future, the team wants to test this technology in icy environments like Antarctica. Those could serve as analogs to Europa and other ocean worlds, where liquid samples would be more readily plentiful.

Opportunity’s Milestones: Not Just Science

The bright landing platform left behind by NASA’s Mars Exploration Rover Opportunity in 2004 is visible inside Eagle Crater, at upper right in this April 8, 2017, observation by NASA’s Mars Reconnaissance Orbiter. Credit: NASA/JPL-Caltech/Univ. of Arizona.

NASA’s Mars Exploration Rover (MER) mission has been successful beyond the mission planners’ wildest dreams. Rovers Spirit and Opportunity landed on the surface of Mars in 2004 in what were originally designed to be a 90-day missions to explore the martian surface and geology. The success of the two rovers led to a subsequent mission, with NASA landing its larger rover Curiosity on Mars in 2012.

But the success of Spirit and Opportunity isn’t just limited to their science discoveries. A new observation from NASA’s Mars Reconnaissance Orbiter (MRO) captures the landing platform that the rover Opportunity left behind in Eagle Crater more than 13 years and 44 kilometers (27 miles) ago.

A series of bounces and tumbles after initial touchdown plunked the airbag-cushioned lander into the crater, a mere 22 meters (72 feet) across, on January 25, 2004, Universal Time (January 24, Pacific Standard Time). The scene shown in the image, captured on April 10, 2017, by MRO’s High Resolution Imaging Science Experiment (HiRISE) camera, includes Eagle Crater (upper right) and Opportunity’s nearby parachute and backshell (lower left). The smattering of small craters on a broad plain is a reminder of the amazement expressed in 2004 about Opportunity achieving a “hole-in-one” landing. When the lander’s petals opened and Opportunity sent home its first look at its surroundings, it provided the first-ever close-by view of sedimentary rocks on Mars, in Eagle’s rim. After leaving the lander and exploring Eagle Crater, the rover recorded a look-back view before departing the scene.

Opportunity remains active more than 13 years later. It recently departed “Cape Tribulation,” a crater-rim segment it had explored since late 2014, then headed southbound to its next destination, “Perseverance Valley.” The rover team planned observations in the valley to determine what type of fluid activity carved it billions of years ago: water, wind, or flowing debris lubricated by water.

A color panorama of a ridge called “Rocheport” provided both a parting souvenir of Cape Tribulation and also possible help for understanding the valley ahead. “The degree of erosion at Rocheport is fascinating,” said Opportunity Deputy Principal Investigator Ray Arvidson, of Washington University in St. Louis. “Grooves run perpendicular to the crest line. They may have been carved by water or ice or wind. We [wanted] to see as many features like this on the way to Perseverance Valley as we [could], for comparison with what we find there.”

Cape Tribulation has been the site of significant events in the mission. There, in 2015, Opportunity surpassed a marathon-race distance of total driving since its 2004 landing on Mars. It climbed to the highest-elevation viewpoint it has reached on Endeavour’s rim. In a region of Tribulation called “Marathon Valley,” it investigated outcrops containing clay minerals that had been detected from orbit. There were some name-appropriate Tribulation experiences, as well. The rover team has coped with loss of reliability in Opportunity’s non-volatile “flash” memory since 2015. With flash memory unavailable, each day’s observations are lost if not radioed homeward the same day.

The rover’s next target, Perseverance Valley, is about two football fields long. It cuts downward west to east across the western rim of Endeavour Crater. The crater is about 22 kilometers (14 miles) in diameter, with a segmented rim that exposes the oldest rocks ever investigated in place on Mars. Opportunity had less than four football fields’ distance of driving to reach the top of the valley after departing Cape Tribulation. Clues to how the valley was carved could come from the arrangement of different sizes of rocks and gravel in the deposits.

As the rover approached the upper end of Perseverance Valley in early May, images from its cameras began showing parts of the area in greater resolution than what can be seen in images taken from orbit above Mars. “The science team is really jazzed at starting to see this area up close and looking for clues to help us distinguish among multiple hypotheses about how the valley formed,” said Opportunity Project Scientist Matt Golombek of NASA’s Jet Propulsion Laboratory (JPL).

The process that carved Perseverance Valley into the rim of Endeavour Crater billions of years ago has not yet been identified. Among the possibilities are that it might have been flowing water, or might have been a debris flow in which a small amount of water lubricated a turbulent mix of mud and boulders, or might have been an even drier process such as wind erosion. The mission’s main objective with Opportunity at this site is to assess which possibility is best supported by the evidence still in place.

The upper end of the valley is at a broad notch in the crest of the crater rim. The rover team’s plan for investigating the area begins with taking sets of images of the valley from two widely separated points at that dip in the rim. This long-baseline stereo imaging will provide information for extraordinarily detailed three-dimensional analysis of the terrain. The valley extends down from the rim’s crest line into the crater, at a slope of about 15° to 17° for a distance of about two football fields. “The long-baseline stereo imaging will be used to generate a digital elevation map that will help the team carefully evaluate possible driving routes down the valley before starting the descent,” said Opportunity Project Manager John Callas of JPL.

Reversing course back uphill when partway down could be difficult, so finding a path with minimum obstacles will be important for driving Opportunity through the whole valley. Researchers intend to use the rover to examine textures and compositions at the top, throughout the length and at the bottom, as part of investigating the valley’s history.

While the stereo imaging is being analyzed for drive-planning, the team plans to use the rover to examine the area immediately west of the crater rim at the top of the valley. “We expect to do a little ‘walkabout’ just outside the crater before driving down Perseverance Valley,” Golombek said.

Now more than 13 years into a mission originally scheduled to last 3 months, Opportunity remains unexpectedly capable of continued exploration. It has driven about two-thirds of a kilometer (four-tenths of a mile) since the start of 2017, bringing the total traverse so far to 44.4 kilometers (27.6 miles). The current season on Mars is past the period when global dust storms might arise and curtail Opportunity’s solar power. Opportunity and the next-generation Mars rover, Curiosity, as well as three active NASA Mars orbiters and surface missions to launch in 2018 and 2020, are all part of ambitious robotic exploration to understand Mars, which helps lead the way for sending humans to Mars in the 2030s.

For more information about NASA’s Mars Exploration Program, visit https://mars.nasa.gov/.

Prolific Mars Orbiter Completes 50,000 Orbits

The Context Camera (CTX) on NASA’s Mars Reconnaissance Orbiter (MRO) has been taking images of Mars for more than 10 years, sharp enough to show the shapes of features as small as a tennis court. The compiled images from CTX now cover more than 99% of Mars. Credit: NASA/JPL-Caltech/MSSS.

The most data-productive spacecraft yet at Mars swept past its 50,000th orbit on March 27, continuing to compile the most sharp-eyed global coverage ever accomplished by a camera at the Red Planet. In addition, the spacecraft — NASA’s Mars Reconnaissance Orbiter (MRO) — recently aided preparations for NASA’s next mission to Mars, the InSight lander. InSight will launch next year on a mission to study the planet’s deep interior. Meanwhile, the orbiter continues diverse science observations of Mars and communications-relay service for two active Mars rovers, Curiosity and Opportunity.

MRO’s Context Camera (CTX) exploits a sweet spot in the balance between resolution and image file size. With a resolution of about 6 meters (20 feet) per pixel in images of the martian surface, it has provided a library of images now covering 99.1% of Mars. No other camera ever sent to Mars has photographed so much of the planet in such high resolution. The Context Camera has taken about 90,000 images since the spacecraft began examining Mars from orbit in late 2006. Each one reveals shapes of features down to sizes smaller than a tennis court, in a swath of ground about 18.6 miles (30 kilometers) wide. “Reaching 99.1% coverage has been tricky because a number of factors, including weather conditions, coordination with other instruments, downlink limitations, and orbital constraints, tend to limit where we can image and when,” said Context Camera Team Leader Michael Malin of Malin Space Science Systems, San Diego.

In addition to observing nearly the entire planet at least once, the Context Camera has observed 60.4% of the planet more than once. These observations aid science directly and also certify the safety of future landing sites. Malin said, “Single coverage provides a baseline we can use for comparison with future observations, as we look for changes. Reimaging areas serves two functions: looking for changes and acquiring stereoscopic views from which we can make topographic maps.”

A dramatic type of change the Context Camera has documented more than 200 times is a fresh impact crater appearing between the times of two observations. These images enabled scientists to calculate the rate at which small asteroids, or bits of comets, are colliding with Mars. Some of the fresh impacts reveal white material interpreted as water ice. The latitudes and estimated depths of the ice-exposing craters provide evidence about the distribution of buried ice near the surface. MRO’s Shallow Radar has found ice farther underground, but this very shallow ice would go undetected if not for its exposure by impacts.

One of MRO’s other cameras, the High Resolution Imaging Science Experiment (HiRISE), can zoom in on the new impact craters found by the Context Camera. For some of these craters, HiRISE and MRO’s Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) have confirmed the presence of water ice. However, even though MRO has returned more than 300 terabits of science data, the much higher spatial resolution of HiRISE has limited its coverage of Mars’ surface to about 3%. A third MRO camera, the Mars Color Imager, observes almost the entire planet every day to track weather change. Another instrument, the Mars Climate Sounder, records vertical profiles of the atmosphere’s temperatures and suspended particles.

The spacecraft was launched August 12, 2005. It entered an elongated orbit of Mars in March 2006, then spent several months using friction with Mars’ upper atmosphere to revise its orbit. Since beginning its science operations in November 2006, MRO has been flying near-polar orbits lasting about two hours, at altitudes from 250 to 316 kilometers (155 to 196 miles). The mission completed its 50,000th orbit on Monday, March 27.

“After 11 and a half years in flight, the spacecraft is healthy and remains fully functional,” said MRO Project Manager Dan Johnston at NASA’s Jet Propulsion Laboratory, Pasadena, California. “It’s a marvelous vehicle that we expect will serve the Mars Exploration Program and Mars science for many more years to come.” For additional information, visit http://nasa.gov/mro.

NASA Rover Samples Active Linear Dune on Mars

This view from the Mast Camera (Mastcam) on NASA’s Curiosity Mars rover shows two scales of ripples, plus other textures, in an area where the mission examined a linear-shaped dune in the Bagnold dune field on lower Mount Sharp in March and April 2017. Credit: NASA/JPL-Caltech/MSSS.

As it drives uphill from a band of rippled sand dunes, NASA’s Curiosity Mars rover is toting a fistful of dark sand for onboard analysis that will complete the rover’s investigation of those dunes. From early February to early April, the rover examined four sites near a linear dune for comparison with what it found in late 2015 and early 2016 during its investigation of crescent-shaped dunes. This two-phase campaign is the first close-up study of active dunes anywhere other than Earth.

Among the questions this martian dune campaign is addressing is how winds shape dunes that are relatively close together, on the same side of the same mountain, into different patterns. Others include whether martian winds sort grains of sand in ways that affect the distribution of mineral compositions, which would have implications for studies of martian sandstones. “At these linear dunes, the wind regime is more complicated than at the crescent dunes we studied earlier,” said Mathieu Lapotre of the California Institute of Technology, who helped lead the Curiosity science team’s planning for the dune campaign. “There seems to be more contribution from the wind coming down the slope of the mountain here compared with the crescent dunes farther north.”

The linear dunes lie uphill and about about 1.6 kilometers (about 1 mile) south from the crescent dunes. Both study locations are part of a dark-sand swath called the Bagnold Dunes, which stretches several miles in length. This dune field lines the northwestern flank of Mount Sharp, the layered mountain that Curiosity is climbing. “There was another key difference between the first and second phases of our dune campaign, besides the shape of the dunes,” Lapotre said. “We were at the crescent dunes during the low-wind season of the martian year and at the linear dunes during the high-wind season. We got to see a lot more movement of grains and ripples at the linear dunes.”

To assess wind strength and direction, the rover team now uses change-detection pairs of images taken at different times to check for movement of sand grains. The wind-sensing capability of the Curiosity’s Rover Environmental Monitoring Station (REMS) is no longer available, although that instrument still returns other Mars-weather data daily, such as temperatures, humidity, and pressure. Two of the six wind sensors on the rover’s mast were found to be inoperable upon landing on Mars in 2012. The remainder provided wind information throughout the rover’s prime mission and first two-year extended mission.

A sample of sand that Curiosity scooped up from a linear dune is in the sample-handling device at the end of the rover’s arm. One portion has been analyzed in the Sample Analysis at Mars (SAM) instrument inside the rover. The science team plans to deliver additional sample portions to SAM and to the rover’s Chemistry and Mineralogy (CheMin) instrument.

One factor in choosing to drive farther uphill before finishing analysis of the scooped sand is the status of Curiosity’s rock-sampling drill, which has not been used on a rock since a problem with the drill feed mechanism appeared five months ago. Engineers are assessing how the use of vibration to deliver samples may affect the drill-feed mechanism, which is used to move the drill bit forward and backward. In addition, high winds at the linear-dunes location were complicating the process of pouring sample material into the entry ports for the laboratory instruments. “A balky brake appears to be affecting drill feed mechanism performance,” said Curiosity Deputy Project Manager Steven Lee, of NASA’s Jet Propulsion Laboratory. “In some cases, vibration has been observed to change feed effectiveness, so we’re proceeding cautiously until we better understand the behavior. In the meantime, the engineering team is developing several methods to improve feed reliability.”

Curiosity landed near Mount Sharp in August 2012. It reached the base of the mountain in 2014 after successfully finding evidence on the surrounding plains that ancient martian lakes offered conditions that would have been favorable for microbes if Mars has ever hosted life. Rock layers forming the base of Mount Sharp accumulated as sediment within ancient lakes billions of years ago. On Mount Sharp, Curiosity is investigating how and when the ancient habitable conditions known from the mission’s earlier findings evolved into drier conditions that were less favorable for life. For more information about Curiosity, visit http://mars.jpl.nasa.gov/msl.

Mars Volcano, Earth’s Dinosaurs Went Extinct About the Same Time

New research using observations from NASA’s Mars Reconnaissance Orbiter indicates that Arsia Mons, one of the largest volcanos on Mars, actively produced lava flows until about 50 million years ago. This wide view of the volcano is from the Viking 1 Orbiter. Credit: NASA/JPL/USGS.

New NASA research reveals that the giant martian volcano Arsia Mons produced one new lava flow at its summit every 1 to 3 million years during the final peak of activity. The last volcanic activity there ceased about 50 million years ago — around the time of Earth’s Cretaceous-Paleogene extinction, when large numbers of our planet’s plant and animal species (including dinosaurs) went extinct.

Located just south of Mars’ equator, Arsia Mons is the southernmost member of a trio of broad, gently sloping shield volcanos collectively known as Tharsis Montes. Arsia Mons was built up over billions of years, although the details of its lifecycle are still being worked out. The most recent volcanic activity is thought to have taken place in the caldera — the bowl-shaped depression at the top — where 29 volcanic vents have been identified. Until now, it’s been difficult to make a precise estimate of when this volcanic field was active.

“We estimate that the peak activity for the volcanic field at the summit of Arsia Mons probably occurred approximately 150 million years ago — the late Jurassic period on Earth — and then died out around the same time as Earth’s dinosaurs,” said Jacob Richardson, a postdoctoral researcher at NASA’s Goddard Space Flight Center. “It’s possible, though, that the last volcanic vent or two might have been active in the past 50 million years, which is very recent in geological terms.” Richardson presented the findings in March at the Lunar and Planetary Science Conference in The Woodlands, Texas. The study was also published in Earth and Planetary Science Letters.

Measuring about 110 kilometers (68 miles) across, the caldera is deep enough to hold the entire volume of water in Lake Huron and then some. Examining the volcanic features within the caldera required high-resolution imaging, which the researchers obtained from the Context Camera on NASA’s Mars Reconnaissance Orbiter. The team mapped the boundaries of the lava flows from each of the 29 volcanic vents and determined the stratigraphy, or layering, of the flows. The researchers also performed a technique called crater counting — tallying up the number of craters at least 100 meters (330 feet) in diameter — to estimate the ages of the flows.

Using a new computer model developed by Richardson and his colleagues at the University of South Florida, the two types of information were combined to determine the volcanic equivalent of a batting order for Arsia Mons’ 29 vents. The oldest flows date back about 200 million years. The youngest flows probably occurred 10 to 90 million years ago — most likely around 50 million years ago. The modeling also yielded estimates of the volume flux for each lava flow. At their peak about 150 million years ago, the vents in the Arsia Mons’ caldera probably collectively produced about 1 to 8 cubic kilometers (0.25 to 2 cubic miles) of magma every million years, slowly adding to the volcano’s size. “Think of it like a slow, leaky faucet of magma,” said Richardson. “Arsia Mons was creating about one volcanic vent every 1 to 3 million years at the peak, compared to one every 10,000 years or so in similar regions on Earth.”

A better understanding of when volcanic activity on Mars took place is important because it helps researchers understand the Red Planet’s history and interior structure. “A major goal of the Mars volcanology community is to understand the anatomy and lifecycle of the planet’s volcanos. Mars’ volcanos show evidence for activity over a larger time span than those on Earth, but their histories of magma production might be quite different,” said Jacob Bleacher, a planetary geologist at Goddard and a co-author on the study. “This study gives us another clue about how activity at Arsia Mons tailed off and the huge volcano became quiet.”

Does Mars Have Rings? Not Right Now, But Maybe One Day

A sequence of images from NASA’s Curiosity Mars rover shows one of Mars’ two moons, Phobos, passing directly in front of the other, Deimos, in 2013. Credit: NASA/JPL-Caltech/Malin Space Science Systems/Texas A&M Univ.

As children, we learned about our solar system’s planets by certain characteristics — Jupiter is the largest, Saturn has rings, Mercury is closest to the Sun. Mars is red, but it’s possible that one of our closest neighbors also had rings at one point and may have them again someday. That’s the theory put forth by NASA-funded scientists at Purdue University, Lafayette, Indiana, whose findings were published in the journal Nature Geoscience. David Minton and Andrew Hesselbrock developed a model that suggests that debris that was pushed into space from an asteroid or other body slamming into Mars around 4.3 billion years ago alternates between becoming a planetary ring and clumping together to form a moon.

One theory suggests that Mars’ large North Polar Basin or Borealis Basin — which covers about 40% of the planet in its northern hemisphere — was created by that impact, sending debris into space. “That large impact would have blasted enough material off the surface of Mars to form a ring,” Hesselbrock said.

Hesselbrock and Minton’s model suggests that as the ring formed, and the debris slowly moved away from the Red Planet and spread out, it began to clump and eventually formed a moon. Over time, Mars’ gravitational pull would have pulled that moon toward the planet until it reached the Roche limit, the distance within which a planet’s tidal forces will break apart a celestial body that is held together only by gravity.

Phobos, one of Mars’ moons, is getting closer to the planet. According to the model, Phobos will break apart upon reaching the Roche limit, and become a set of rings in roughly 70 million years. Depending on where the Roche limit is, Minton and Hesselbrock believe this cycle may have repeated between three and seven times over billions of years. Each time a moon broke apart and reformed from the resulting ring, its successor moon would be five times smaller than the last, according to the model, and debris would have rained down on the planet, possibly explaining enigmatic sedimentary deposits found near Mars’ equator. “You could have had kilometer-thick piles of moon sediment raining down on Mars in the early parts of the planet’s history, and there are enigmatic sedimentary deposits on Mars with no explanation as to how they got there,” Minton said. “And now it’s possible to study that material.”

Other theories suggest that the impact with Mars that created the North Polar Basin led to the formation of Phobos 4.3 billion years ago, but Minton said it’s unlikely the moon could have lasted all that time. Also, Phobos would have had to form far from Mars and would have had to cross through the resonance of Deimos, the outer of Mars’ two moons. Resonance occurs when two moons exert gravitational influence on each other in a repeated periodic basis, as major moons of Jupiter do. By passing through its resonance, Phobos would have altered Deimos’ orbit. But Deimos’ orbit is within 1° of Mars’ equator, suggesting Phobos has had no effect on Deimos. “Not much has happened to Deimos’ orbit since it formed,” Minton said. “Phobos passing through these resonances would have changed that.”

“This research highlights even more ways that major impacts can affect a planetary body,” said Richard Zurek of NASA’s Jet Propulsion Laboratory. He is the project scientist for NASA’s Mars Reconnaissance Orbiter, whose gravity mapping provided support for the hypothesis that the northern lowlands were formed by a massive impact. Minton and Hesselbrock will now focus their work on either the dynamics of the first set of rings that formed or the materials that have rained down on Mars from disintegration of moons.

NASA Moves Up Launch of Psyche Mission to a Metal Asteroid

Artist’s concept of the Psyche spacecraft, which will conduct a direct exploration of an asteroid thought to be a stripped planetary core. Credit: SSL/ASU/P. Rubin/NASA/JPL-Caltech.

Psyche, NASA’s Discovery Mission to a unique metal asteroid, has been moved up one year with launch in the summer of 2022, and with a planned arrival at the main-belt asteroid in 2026 — four years earlier than the original timeline. “We challenged the mission design team to explore if an earlier launch date could provide a more efficient trajectory to the asteroid Psyche, and they came through in a big way,” said Jim Green, director of the Planetary Science Division at NASA Headquarters in Washington. “This will enable us to fulfill our science objectives sooner and at a reduced cost.”

The Discovery program announcement of opportunity had directed teams to propose missions for launch in either 2021 or 2023. The Lucy mission was selected for the first launch opportunity in 2021, and Psyche was to follow in 2023. Shortly after selection in January, NASA gave the direction to the Psyche team to research earlier opportunities. “The biggest advantage is the excellent trajectory, which gets us there about twice as fast and is more cost effective,” said Principal Investigator Lindy Elkins-Tanton of Arizona State University in Tempe. “We are all extremely excited that NASA was able to accommodate this earlier launch date. The world will see this amazing metal world so much sooner.”

The revised trajectory is more efficient, as it eliminates the need for an Earth-gravity assist, which ultimately shortens the cruise time. In addition, the new trajectory stays farther from the Sun, reducing the amount of heat protection needed for the spacecraft. The trajectory will still include a Mars gravity assist in 2023. In order to support the new mission trajectory, the spacecraft’s solar array system is being redesigned from a four-panel array in a straight row on either side of the spacecraft to a more powerful five-panel x-shaped design, commonly used for missions requiring more capability. Much like a sports car, by combining a relatively small spacecraft body with a very high-power solar array design, the Psyche spacecraft will speed to its destination at a faster pace than is typical for a larger spacecraft. Increasing the size of the solar arrays will give the spacecraft the power it needs to support the higher-velocity requirements of the updated mission.

Psyche, an asteroid orbiting the Sun between Mars and Jupiter, is made almost entirely of nickel-iron metal. As such, it offers a unique look into the violent collisions that created Earth and the terrestrial planets. The Psyche mission was selected for flight earlier this year under NASA’s Discovery Program, a series of lower-cost, highly focused robotic space missions that are exploring the solar system.

The scientific goals of the Psyche mission are to understand the building blocks of planet formation and explore firsthand a wholly new and unexplored type of world. The mission team seeks to determine whether Psyche is the core of an early planet, how old it is, whether it formed in similar ways to Earth’s core, and what its surface is like. The spacecraft’s instrument payload will include magnetometers, multispectral imagers, and a gamma ray and neutron spectrometer. For more information, visit http://www.nasa.gov/psyche.

Landslides on Ceres Reflect Ice Content

NASA’s Dawn spacecraft has revealed many landslides on Ceres, which researchers interpret to have been shaped by a significant amount of water ice. Shown are examples of Type I (left), Type II (middle), and Type III (right). Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.

As NASA’s Dawn spacecraft continues exploring Ceres, evidence mounts that the enigmatic dwarf planet retains a significant amount of water ice. A new study in the journal Nature Geoscience adds to this picture, showing how ice may have shaped the variety of landslides seen on Ceres today. “Images from Dawn show that landslides, many of which are similar to those seen on Earth, are very common on Ceres, and further the case that Ceres has a lot of water ice involved in its structure,” said Britney Schmidt, who led the study. She is an associate of the Dawn science team and assistant professor at Georgia Institute of Technology in Atlanta.

Schmidt and colleagues identified three types of landslides. Type I, which are relatively round and large, have thick “toes” at their ends. They look similar to rock glaciers and icy landslides on Earth. Type I landslides are mostly found at high latitudes on Ceres, which is also where most of the ice is thought to reside just beneath the surface, suggesting they involve the most ice of any of the flow features. Three small Type I flows are found in Oxo Crater, a tiny bright crater in the northern hemisphere that hosts an ice deposit at the surface. Type II features are often thinner and longer than Type I, and are the most common type of landslide on Ceres. The landslide deposits appear similar to those left behind by avalanches seen on Earth.

Ceres’ Type III features may involve a brief melting of some of the ice within the soil-like regolith, causing the material to flow like mud before refreezing. These landslides are always associated with large impact craters, and may have formed when an impact event melts subsurface ice on Ceres. These features have similar appearances to ejected material from craters in the icy regions of Mars and on Jupiter’s moon Ganymede. “The locations of these different types of features reinforces the idea that the shallow subsurface of Ceres is a mixture of ice and rock, and that ice is most plentiful near the surface at the poles,” Schmidt said.

Scientists were also surprised at just how many landslides have occurred on Ceres in general. About 20–% of craters greater than 10 kilometers (6 miles) wide have some type of landslide associated with them. Such widespread “ground ice” features, which formed from of a mixture of rock and ice, had only been observed before on Earth and Mars.

Based on the shape and distribution of landslides on Ceres, study authors estimate that the ice in the upper few tens of meters of Ceres may range from 10% to 50% by volume. “These kinds of flows are not seen on bodies such as Vesta, which Dawn studied from 2011 to 2012, because the regolith is devoid of water,” said Carol Raymond, deputy principal investigator for the Dawn mission, based at NASA’s Jet Propulsion Laboratory.

Now in its extended mission phase, Dawn is using its ion engine to swivel the plane of its orbit around Ceres to prepare for observations from a new orbit and orientation. At the end of April, the spacecraft was directly between the Sun and the mysterious Occator Crater. In this geometry, Dawn may deliver new insights about the reflective material of Ceres’ most famous “bright spot,” the highly reflective center of Occator that has been named Cerealia Facula. For more information, visit https://www.nasa.gov/dawn or https://dawn.jpl.nasa.gov.

Ceres’ Temporary Atmosphere Linked to Solar Activity

This frame from an animation shows dwarf planet Ceres overlaid with the concentration of hydrogen determined by data acquired by the Gamma Ray and Neutron Detector (GRaND) instrument onboard the Dawn spacecraft. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI.

Scientists have long thought that Ceres may have a very weak, transient atmosphere, but mysteries lingered about its origin and why it’s not always present. Now, researchers suggest that this temporary atmosphere appears to be related to the behavior of the Sun, rather than Ceres’ proximity to the Sun. The study was conducted by scientists from NASA’s Dawn mission and others who previously identified water vapor at Ceres using other observatories. “We think the occurrence of Ceres’ transient atmosphere is the product of solar activity,” said Michaela Villarreal, lead author of the new study published in Astrophysical Journal Letters and researcher at the University of California, Los Angeles (UCLA).

Ceres is the largest object in the asteroid belt that lies between Mars and Jupiter. When energetic particles from the Sun hit exposed ice and ice near the surface of the dwarf planet, it transfers energy to the water molecules as they collide. This frees the water molecules from the ground, allowing them to escape and create a tenuous atmosphere that may last for a week or so. “Our results also have implications for other airless, water-rich bodies of the solar system, including the polar regions of the Moon and some asteroids,” said Chris Russell, principal investigator of the Dawn mission, also at UCLA. “Atmospheric releases might be expected from their surfaces, too, when solar activity erupts.”

Before Dawn arrived in orbit at Ceres in 2015, evidence for an atmosphere had been detected by some observatories at certain times, but not others, suggesting that it is a transient phenomenon. The International Ultraviolet Explorer satellite detected hydroxyl emission from Ceres in 1991, but not in 1990. Then, in 2007, the European Southern Observatory’s Very Large Telescope searched for a hydroxide emission, but came up empty. The European Space Agency’s Herschel Space Observatory detected water in the possible weak atmosphere, or “exosphere,” of Ceres on three occasions, but did not on a fourth attempt.

As Dawn began its thorough study of Ceres in March 2015, scientists found ample evidence for water in the form of ice. The spacecraft’s gamma ray and neutron detector (GRaND) has found that the uppermost surface is rich in hydrogen, which is consistent with broad expanses of water ice. This ice is nearer to the surface at higher latitudes, where temperatures are lower, according to a 2016 study published in the journal Science. Ice has been detected directly at the small bright crater called Oxo and in at least one of the craters that are persistently in shadow in the northern hemisphere. Other research has suggested that persistently shadowed craters are likely to harbor ice. Additionally, the shapes of craters and other features are consistent with significant water-ice content in the crust. Because of this evidence for abundant ice, many scientists think that Ceres’ exosphere is created in a process similar to what occurs on comets, even though they are much smaller. In that model, the closer Ceres gets to the Sun, the more water vapor is released because of ice sublimating near or at the surface.

But the new study suggests comet-like behavior may not explain the mix of detections and non-detections of a weak atmosphere. “Sublimation probably is present, but we don’t think it’s significant enough to produce the amount of exosphere that we’re seeing,” Villarreal said.

Villarreal and colleagues showed that past detections of the transient atmosphere coincided with higher concentrations of energetic protons from the Sun. Non-detections coincided with lower concentrations of these particles. What’s more, the best detections of Ceres’ atmosphere did not occur at its closest approach to the Sun. This suggests that solar activity, rather than Ceres’ proximity to the Sun, is a more important factor in generating an exosphere.

In its orbital path, Ceres is currently getting closer to the Sun. But the Sun is now in a particularly quiet period, expected to last for several more years. Since their results indicate Ceres’ exosphere is related to solar activity, study authors are predicting that the dwarf planet will have little to no atmosphere for some time. However, they recommend that other observatories monitor Ceres for future emissions.

Ice in Ceres’ Shadowed Craters Linked to Tilt History

This still frame is from an animation showing how the illumination of Ceres’ northern hemisphere varies with the dwarf planet’s axial tilt, or obliquity. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.

Dwarf planet Ceres may be hundreds of millions of miles from Jupiter, and even farther from Saturn, but the tremendous influence of gravity from these gas giants has an appreciable effect on Ceres’ orientation. In a new study, researchers from NASA’s Dawn mission calculate that the axial tilt of Ceres — the angle at which it spins as it journeys around the Sun — varies widely over the course of about 24,500 years. Astronomers consider this to be a surprisingly short period of time for such dramatic deviations.

Changes in axial tilt, or “obliquity,” over the history of Ceres are related to the larger question of where frozen water can be found on Ceres’ surface, scientists report in the journal Geophysical Research Letters. Given conditions on Ceres, ice would only be able to survive at extremely cold temperatures — for example, in areas that never see the Sun.

“We found a correlation between craters that stay in shadow at maximum obliquity, and bright deposits that are likely water ice,” said Anton Ermakov, postdoctoral researcher at NASA’s Jet Propulsion Laboratory (JPL) and lead author of the study. “Regions that never see sunlight over millions of years are more likely to have these deposits.”

Throughout the last 3 million years, Ceres has gone through cycles where its tilt ranges from about 2° to about 20°, calculations indicate. “We cannot directly observe the changes in Ceres’ orientation over time, so we used the Dawn spacecraft’s measurements of shape and gravity to precisely reconstruct what turned out to be a dynamic history,” said Erwan Mazarico, a co-author at NASA’s Goddard Space Flight Center.

The last time the dwarf planet reached a maximum tilt, which was about 19°, was 14,000 years ago, researchers said. For comparison, Earth is tilted 23.5°. This significant tilt causes our planet to experience seasons: The northern hemisphere experiences summer when it is oriented toward the Sun, and winter when it’s pointed away from the Sun. By contrast, Ceres’ current tilt is about 4°, so it will not have such strong seasonal effects over the course of a year there (which is about 4.6 Earth years).

When the axial tilt is small, relatively large regions on Ceres never receive direct sunlight, particularly at the poles. These persistently shadowed regions occupy an area of about 2000 square kilometers (800 square miles). However, when the obliquity increases, more of the craters in the polar regions receive direct exposure to the Sun, and persistently shadowed areas only occupy 1–10 square kilometers (0.4–4 square miles). These areas on Ceres’ surface, which stay in shadow even at high obliquity, may be cold enough to maintain surface ice, Dawn scientists said.

These craters with areas that stay in shadow over long periods of time are called “cold traps,” because they are so cold and dark that volatiles — substances easily vaporized — that migrate into these areas can’t escape, even over a billion years. A 2016 study by the Dawn team in Nature Astronomy found bright material in 10 of these craters, and data from Dawn’s visible and infrared mapping spectrometer indicate that one of them contains ice.

The new study focused on polar craters and modeled how shadowing progresses as Ceres’ axial tilt varies. In the northern hemisphere, only two persistently shadowed regions remain in shadow at the maximum 20° tilt. Both of these regions have bright deposits today. In the southern hemisphere, there are also two persistently shadowed regions at highest obliquity, and one of them clearly has a bright deposit.

Ceres is the third body in the solar system found to have permanently shadowed regions. Mercury and Earth’s Moon are the other two, and scientists believe they received their ice from impacting bodies. However, Mercury and the Moon do not have such wide variability in their tilts because of the stabilizing gravitational influence of the Sun and Earth, respectively. The origin of the ice in Ceres’ cold traps is more mysterious — it may come from Ceres itself, or may be delivered by impacts from asteroids and comets. Regardless, the presence of ice in cold traps could be related to a tenuous water atmosphere, which was detected by ESA’s Herschel Space Observatory in 2012–2013. Water molecules that leave the surface would fall back onto Ceres, with some landing in cold traps and accumulating there.

“The idea that ice could survive on Ceres for long periods of time is important as we continue to reconstruct the dwarf planet’s geological history, including whether it has been giving off water vapor,” said Carol Raymond, deputy principal investigator of the Dawn mission and study co-author, based at JPL.

A Whole New Jupiter: First Science Results from NASA’s Juno Mission

This image shows Jupiter’s south pole, as seen by NASA’s Juno spacecraft from an altitude of 52,000 kilometers (32,000 miles). Credit: NASA/JPL-Caltech/SwRI/MSSS/Betsy Asher Hall/Gervasio Robles.

Early science results from NASA’s Juno mission to Jupiter portray the largest planet in our solar system as a complex, gigantic, turbulent world, with Earth-sized polar cyclones; plunging storm systems that travel deep into the heart of the gas giant; and a mammoth, lumpy magnetic field that may indicate it was generated closer to the planet’s surface than previously thought. “We are excited to share these early discoveries, which help us better understand what makes Jupiter so fascinating,” said Diane Brown, Juno program executive at NASA Headquarters in Washington. “It was a long trip to get to Jupiter, but these first results already demonstrate it was well worth the journey.”

Juno launched on August 5, 2011, entering Jupiter’s orbit on July 4, 2016. The findings from the first data-collection pass, which flew within about 4200 kilometers (2600 miles) of Jupiter’s swirling cloud tops on August 27, were published at the end of May in two papers in the journal Science, as well as 44 papers in Geophysical Research Letters. “We knew, going in, that Jupiter would throw us some curves,” said Scott Bolton, Juno principal investigator from the Southwest Research Institute in San Antonio. “But now that we are here we are finding that Jupiter can throw the heat, as well as knuckleballs and sliders. There is so much going on here that we didn’t expect that we have had to take a step back and begin to rethink of this as a whole new Jupiter.”

Among the findings that challenge assumptions are those provided by Juno’s imager, JunoCam. The images show both of Jupiter’s poles are covered in Earth-sized swirling storms that are densely clustered and rubbing together. “We’re puzzled as to how they could be formed, how stable the configuration is, and why Jupiter’s north pole doesn’t look like the south pole,” said Bolton. “We’re questioning whether this is a dynamic system, and are we seeing just one stage, and over the next year, we’re going to watch it disappear, or is this a stable configuration and these storms are circulating around one another?”

Another surprise comes from Juno’s Microwave Radiometer (MWR), which samples the thermal microwave radiation from Jupiter’s atmosphere, from the top of the ammonia clouds to deep within its atmosphere. The MWR data indicates that Jupiter’s iconic belts and zones are mysterious, with the belt near the equator penetrating all the way down, while the belts and zones at other latitudes seem to evolve to other structures. The data suggest the ammonia is quite variable and continues to increase as far down as we can see with MWR, which is a few hundred miles or kilometers.

Prior to the Juno mission, it was known that Jupiter had the most intense magnetic field in the solar system. Measurements of the massive planet’s magnetosphere, from Juno’s magnetometer investigation (MAG), indicate that Jupiter’s magnetic field is even stronger than models expected, and more irregular in shape. MAG data indicates the magnetic field greatly exceeded expectations at 7.766 Gauss, about 10 times stronger than the strongest magnetic field found on Earth.

“Juno is giving us a view of the magnetic field close to Jupiter that we’ve never had before,” said Jack Connerney, Juno deputy principal investigator and the lead for the mission’s magnetic field investigation at NASA’s Goddard Space Flight Center. “Already we see that the magnetic field looks lumpy: It is stronger in some places and weaker in others. This uneven distribution suggests that the field might be generated by dynamo action closer to the surface, above the layer of metallic hydrogen. Every flyby we execute gets us closer to determining where and how Jupiter’s dynamo works.”

Juno is also designed to study the polar magnetosphere and the origin of Jupiter’s powerful auroras — its northern and southern lights. These auroral emissions are caused by particles that pick up energy, slamming into atmospheric molecules. Juno’s initial observations indicate that the process seems to work differently at Jupiter than at Earth. Juno is in a polar orbit around Jupiter, and the majority of each orbit is spent well away from the gas giant. Once every 53 days, its trajectory approaches Jupiter from above its north pole, where it begins a two-hour transit (from pole to pole) flying north to south with its eight science instruments collecting data and its JunoCam public outreach camera snapping pictures. The download of 6 MB of data collected during the transit can take 1.5 days.

“Every 53 days, we go screaming by Jupiter, get doused by a fire hose of jovian science, and there is always something new,” said Bolton. “On our next flyby on July 11, we will fly directly over one of the most iconic features in the entire solar system — one that every school kid knows — Jupiter’s Great Red Spot. If anybody is going to get to the bottom of what is going on below those mammoth swirling crimson cloud tops, it’s Juno and her cloud-piercing science instruments.” For more information about the Juno mission, visit https://www.nasa.gov/juno or http://missionjuno.org.

Experiments Show Titan Lakes May Fizz with Nitrogen

Cassini captured this mosaic of images showing the northern lakes and seas of Saturn’s moon Titan on February 17, 2017. The mission’s final close Titan flyby is planned for April 22. Credit: NASA/JPL-Caltech/Space Science Institute.

A recent NASA-funded study has shown how the hydrocarbon lakes and seas of Saturn’s moon Titan might occasionally erupt with dramatic patches of bubbles. For the study, researchers at NASA’s Jet Propulsion Laboratory (JPL) simulated the frigid surface conditions on Titan, finding that significant amounts of nitrogen can be dissolved in the extremely cold liquid methane that rains from the skies and collects in rivers, lakes, and seas. They demonstrated that slight changes in temperature, air pressure, or composition can cause the nitrogen to rapidly separate out of solution, like the fizz that results when opening a bottle of carbonated soda.

NASA’s Cassini spacecraft has found that the composition of Titan’s lakes and seas varies from place to place, with some reservoirs being richer in ethane than methane. “Our experiments showed that when methane-rich liquids mix with ethane-rich ones — for example, from a heavy rain, or when runoff from a methane river mixes into an ethane-rich lake — the nitrogen is less able to stay in solution,” said Michael Malaska of JPL, who led the study.

The result is bubbles. Lots of bubbles.

The release of nitrogen, known as exsolution, can also occur when methane seas warm slightly during the changing seasons on Titan. A fizzy liquid could also cause problems, potentially, for a future robotic probe sent to float on or swim through Titan’s seas. Excess heat emanating from a probe might cause bubbles to form around its structures — for example, propellers used for propulsion — making it difficult to steer or keep the probe stable.

The notion of nitrogen bubbles creating fizzy patches on Titan’s lakes and seas is relevant to one of the more enchanting unsolved mysteries Cassini has investigated during its time exploring Titan: the so-called “magic islands.” During several flybys, Cassini’s radar has revealed small areas on the seas that appeared and disappeared, and then (in at least one case) reappeared. Researchers proposed several potential explanations for what could be creating these seemingly island-like features, including the idea of fields of bubbles. The new study provides details about the mechanism that could be forming such bubbles, if they are indeed the culprit. “Thanks to this work on nitrogen’s solubility, we’re now confident that bubbles could indeed form in the seas, and in fact may be more abundant than we’d expected,” said Jason Hofgartner of JPL, who serves as a co-investigator on Cassini’s radar team and was a co-author of the study.

In characterizing how nitrogen moves between Titan’s liquid reservoirs and its atmosphere, the researchers also coaxed nitrogen out of a simulated ethane-rich solution as the ethane froze to the bottom of their tiny, simulated Titan lake. Unlike water, which is less dense in its solid form than its liquid form, ethane ice would form on the bottom of Titan’s frigid pools. As the ethane crystalizes into ice, there’s no room for the dissolved nitrogen gas, and it comes fizzing out.

While the thought of hydrocarbon lakes bubbling with nitrogen on an alien moon is dramatic, Malaska points out that the movement of nitrogen on Titan doesn’t just move in one direction. Clearly, it has to get into the methane and ethane before it can get out.

“In effect, it’s as though the lakes of Titan breathe nitrogen,” Malaska said. “As they cool, they can absorb more of the gas, ‘inhaling.’ And as they warm, the liquid’s capacity is reduced, so they ‘exhale.’” A similar phenomenon occurs on Earth with carbon dioxide absorption by our planet’s oceans.

Results of the study were published earlier this year in the journal Icarus.

The Many Faces of Rosetta’s Comet 67P

A 30-meter-wide (100-foot-wide), 12.8-million-kilogram (28-million-pound) boulder was found to have moved 140 meters (460 feet) on Comet 67P/Churyumov-Gerasimenko in the lead up to perihelion in August 2015, when the comet’s activity was at its highest. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA.

Images returned from the European Space Agency’s Rosetta mission indicate that during its most recent trip through the inner solar system, the surface of Comet 67P/Churyumov-Gerasimenko was a very active place — full of growing fractures, collapsing cliffs, and massive rolling boulders. Moving material buried some features on the comet’s surface while exhuming others. A study on 67P’s changing surface was released on March 21 in the journal Science. “As comets approach the Sun, they go into overdrive and exhibit spectacular changes on their surface,” said Ramy El-Maarry, study leader and a member of the U.S. Rosetta science team from the University of Colorado, Boulder. “This is something we were not able to really appreciate before the Rosetta mission, which gave us the chance to look at a comet in ultra-high resolution for more than two years.”

Most comets orbit our Sun in highly elliptical orbits that cause them to spend most of their time in the extremely cold outer solar system. When a comet approaches the inner solar system, the Sun begins to warm the ice on and near the comet’s surface. When the ice warms enough it can rapidly sublimate (turn directly from the solid to the vapor state). This sublimation process can occur with variable degrees of intensity and timescales and cause the surface to change rapidly. Between August 2014 and September 2016, Rosetta orbited Comet 67P during the comet’s swing through the inner solar system. “We saw a massive cliff collapse and a large crack in the neck of the comet get bigger and bigger,” said El-Maarry. “And we discovered that boulders the size of a large truck could be moved across the comet’s surface a distance as long as one-and-a-half football fields.”

In the case of the boulder, Rosetta’s cameras observed a 130-million-kilogram (282-million-pound), 30-meter-wide (100-foot-wide) space rock to have moved 140 meters (460 feet) from its original position on the comet’s nucleus. The massive space rock probably moved as a result of several outburst events that were detected close to its original position.

The warming of 67P also caused the comet’s rotation rate to speed up. The comet’s increasing spin rate in the lead-up to perihelion is thought to be responsible for a 500-meter-long (1600-foot-long) fracture spotted in August 2014 that runs through the comet’s neck. The fracture, which originally extended a bit longer than the Empire State Building is high, was found to have increased in width by about 30 meters (100 feet) by December 2014. Furthermore, in images taken in June 2016, a new 150- to 300-meter-long (500- to 1000-foot-long) fracture was identified parallel to the original fracture. “The large crack was in the ‘neck’ of the comet — a small central part that connects the two lobes,” said El-Maarry. “The crack was extending — indicating that the comet may split up one day.”

“Understanding how comets change and evolve with time gives us important insights into the types and abundance of ices in comets, and how long comets can stay in the inner solar system before losing all their ice and becoming balls of dust,” said El-Maarry. “This helps us better understand the conditions of the early solar system, and possibly even how life started.”

In a second Rosetta study released in April, this one published in Nature Astronomy, scientists made the first definitive link between an outburst of dust and gas from the nucleus of 67P and the collapse of one of its prominent cliffs, which also exposed the comet’s pristine, icy interior.

Comets are time capsules containing primitive material left over from the epoch when the Sun and its planets formed. Rosetta was the first spacecraft to witness at close proximity how a comet changes as it is subjected to the increasing intensity of the Sun’s radiation. Observations will help scientists learn more about the origin and evolution of our solar system and whether comets brought life-sustaining water and organic molecules to Earth. More information is available at http://www.esa.int/rosetta.

Earth-Sized “Tatooine” Planets Could Be Habitable

This artist’s concept shows a hypothetical planet covered in water around the binary star system of Kepler-35A and B. Credit: NASA/JPL-Caltech.

With two suns in its sky, Luke Skywalker’s home planet Tatooine in “Star Wars” looks like a parched, sandy desert world. In real life, thanks to observatories such as NASA’s Kepler space observatory, we know that two-star systems can indeed support planets, although planets discovered so far around double-star systems are large and gaseous. Scientists wondered, if an Earth-sized planet orbited two suns, could it support life?

It turns out, such a planet could be quite hospitable if located at the right distance from its two stars, and wouldn’t necessarily even have deserts. In a particular range of distances from two sun-like host stars, a planet covered in water would remain habitable and retain its water for a long time, according to a new study in the journal Nature Communications. “This means that double-star systems of the type studied here are excellent candidates to host habitable planets, despite the large variations in the amount of starlight hypothetical planets in such a system would receive,” said Max Popp, associate research scholar at Princeton University in New Jersey and the Max Planck Institute of Meteorology in Hamburg, Germany.

Popp and Siegfried Eggl, a California Institute of Technology postdoctoral scholar at NASA’s Jet Propulsion Laboratory, created a model for a planet in the Kepler 35 system. In reality, the stellar pair Kepler 35A and B host a planet called Kepler 35b, a giant planet about eight times the size of Earth, with an orbit of 131.5 Earth days. For their study, researchers neglected the gravitational influence of this planet and added a hypothetical water-covered, Earth-sized planet around the Kepler 35 AB stars. They examined how this planet’s climate would behave as it orbited the host stars with periods between 341 and 380 days.

“Our research is motivated by the fact that searching for potentially habitable planets requires a lot of effort, so it is good to know in advance where to look,” Eggl said. “We show that it’s worth targeting double-star systems.”

In exoplanet research, scientists speak of a region called the “habitable zone,” the range of distances around a star where a terrestrial planet is most likely to have liquid water on its surface. In this case, because two stars are orbiting each other, the habitable zone depends on the distance from the center of mass that both stars are orbiting. To make things even more complicated, a planet around two stars would not travel in a circle; instead, its orbit would wobble through the gravitational interaction with the two stars.

Popp and Eggl found that on the far edge of the habitable zone in the Kepler 35 double-star system, the hypothetical water-covered planet would have a lot of variation in its surface temperatures. Because such a cold planet would have only a small amount of water vapor in its atmosphere, global average surface temperatures would swing up and down by as much as 2°C (3.6°F) in the course of a year. “This is analogous to how, on Earth, in arid climates like deserts, we experience huge temperature variations from day to night,” Eggl said. “The amount of water in the air makes a big difference.”

Closer to the stars, near the inner edge of the habitable zone, the global average surface temperatures on the same planet stay almost constant. That is because more water vapor would be able to persist in the atmosphere of the hypothetical planet and act as a buffer to keep surface conditions comfortable.

As with single-star systems, a planet beyond the outer edge of the habitable zone of its two suns would eventually end up in a so-called “snowball” state, completely covered with ice. Closer than the inner edge of the habitable zone, an atmosphere would insulate the planet too much, creating a runaway greenhouse effect and turning the planet into a Venus-like world inhospitable to life as we know it.

Another feature of the study’s climate model is that, compared to Earth, a water-covered planet around two stars would have less cloud coverage. That would mean clearer skies for viewing double sunsets on these exotic worlds. For more information about exoplanets, visit https://exoplanets.nasa.gov.

“Iceball” Planet Discovered Through Microlensing

This artist’s concept shows OGLE-2016-BLG-1195Lb, a planet discovered through a technique called microlensing. Credit: NASA/JPL-Caltech.

Scientists have discovered a new planet with the mass of Earth, orbiting its star at the same distance that we orbit our Sun. The planet is likely far too cold to be habitable for life as we know it, however, because its star is so faint. But the discovery adds to scientists’ understanding of the types of planetary systems that exist beyond our own. “This ‘iceball’ planet is the lowest-mass planet ever found through microlensing,” said Yossi Shvartzvald, a NASA postdoctoral fellow based at NASA’s Jet Propulsion Laboratory, and lead author of a study published in Astrophysical Journal Letters.

Microlensing is a technique that facilitates the discovery of distant objects by using background stars as flashlights. When a star crosses precisely in front of a bright star in the background, the gravity of the foreground star focuses the light of the background star, making it appear brighter. A planet orbiting the foreground object may cause an additional blip in the star’s brightness. In this case, the blip only lasted a few hours. This technique has found the most distant known exoplanets from Earth, and can detect low-mass planets that are substantially farther from their stars than Earth is from our Sun.

The newly discovered planet, called OGLE-2016-BLG-1195Lb, aids scientists in their quest to figure out the distribution of planets in our galaxy. An open question is whether there is a difference in the frequency of planets in the Milky Way’s central bulge compared to its disk, the pancake-like region surrounding the bulge. OGLE-2016-BLG-1195Lb is located in the disk, as are two planets previously detected through microlensing by NASA’s Spitzer Space Telescope. “Although we only have a handful of planetary systems with well-determined distances that are this far outside our solar system, the lack of Spitzer detections in the bulge suggests that planets may be less common toward the center of our galaxy than in the disk,” said Geoff Bryden, astronomer at JPL and co-author of the study.

For the new study, researchers were alerted to the initial microlensing event by the groundbased Optical Gravitational Lensing Experiment (OGLE) survey, managed by the University of Warsaw in Poland. The planetary signal was recognized in real time by another groundbased survey, the Microlensing Observations in Astrophysics (MOA). Study authors used the Korea Microlensing Telescope Network (KMTNet), operated by the Korea Astronomy and Space Science Institute, and Spitzer, to track the event from Earth and space.

KMTNet consists of three wide-field telescopes: one in Chile, one in Australia, and one in South Africa. When scientists from the Spitzer team received the OGLE alert, they realized the potential for a planetary discovery. The microlensing event alert was only a couple of hours before Spitzer’s targets for the week were to be finalized, but it made the cut.

With both KMTNet and Spitzer observing the event, scientists had two vantage points from which to study the objects involved, as though two eyes separated by a great distance were viewing it. Having data from these two perspectives allowed them measure the masses of the star and the planet, and the distance to the planetary system.

Although OGLE-2016-BLG-1195Lb is about the same mass as Earth, and the same distance from its host star as our planet is from our Sun, the similarities may end there. OGLE-2016-BLG-1195Lb is nearly 13,000 light-years away and orbits a star so small, scientists aren’t sure if it’s a star at all. It could be a brown dwarf, a star-like object whose core is not hot enough to generate energy through nuclear fusion. This particular star is only 7.8% the mass of our Sun, right on the border between being a star and not. Alternatively, it could be an ultra-cool dwarf star much like TRAPPIST-1, which Spitzer and groundbased telescopes recently revealed to host seven Earth-sized planets. Those seven planets all huddle closely around TRAPPIST-1, even closer than Mercury orbits our Sun, and they all have potential for liquid water. But OGLE-2016-BLG-1195Lb, at the Sun-Earth distance from a very faint star, would be extremely cold — likely even colder than Pluto is in our own solar system, such that any surface water would be frozen. A planet would need to orbit much closer to the tiny, faint star to receive enough light to maintain liquid water on its surface.

Groundbased telescopes available today are not able to find smaller planets than this one using the microlensing method. A highly sensitive space telescope would be needed to spot smaller bodies in microlensing events. NASA’s upcoming Wide Field Infrared Survey Telescope (WFIRST), planned for launch in the mid-2020s, will have this capability. “One of the problems with estimating how many planets like this are out there is that we have reached the lower limit of planet masses that we can currently detect with microlensing,” Shvartzvald said. “WFIRST will be able to change that.”

For more information, visit http://spitzer.caltech.edu or http://www.nasa.gov/spitzer.

“Warm Neptune” Has Unexpectedly Primitive Atmosphere

The atmosphere of the distant “warm Neptune” HAT-P-26b, illustrated here, is unexpectedly primitive, composed primarily of hydrogen and helium. Credit: NASA/GSFC.

A study combining observations from NASA’s Hubble and Spitzer space telescopes reveals that the distant planet HAT-P-26b has a primitive atmosphere composed almost entirely of hydrogen and helium. Located about 437 light-years away, HAT-P-26b orbits a star roughly twice as old as the Sun.

The analysis is one of the most detailed studies to date of a “warm Neptune,” or a planet that is Neptune-sized and close to its star. The researchers determined that HAT-P-26b’s atmosphere is relatively clear of clouds and has a strong water signature, although the planet is not a water world. This is the best measurement of water to date on an exoplanet of this size.

The discovery of an atmosphere with this composition on this exoplanet has implications for how scientists think about the birth and development of planetary systems. Compared to Neptune and Uranus, the planets in our solar system with about the same mass, HAT-P-26b likely formed either closer to its host star or later in the development of its planetary system, or both. “Astronomers have just begun to investigate the atmospheres of these distant Neptune-mass planets, and almost right away, we found an example that goes against the trend in our solar system,” said Hannah Wakeford, a postdoctoral researcher at NASA’s Goddard Space Flight Center, and lead author of the study published in the May 12 issue of Science. “This kind of unexpected result is why I really love exploring the atmospheres of alien planets.”

To study HAT-P-26b’s atmosphere, the researchers used data from transits — occasions when the planet passed in front of its host star. During a transit, a fraction of the starlight gets filtered through the planet’s atmosphere, which absorbs some wavelengths of light but not others. By looking at how the signatures of the starlight change as a result of this filtering, researchers can work backward to figure out the chemical composition of the atmosphere.

In this case, the team pooled data from four transits measured by Hubble and two seen by Spitzer. Together, those observations covered a wide range of wavelengths from yellow light through the near-infrared region. “To have so much information about a warm Neptune is still rare, so analyzing these datasets simultaneously is an achievement in and of itself,” said co-author Tiffany Kataria of NASA’s Jet Propulsion Laboratory.

Because the study provided a precise measurement of water, the researchers were able to use the water signature to estimate HAT-P-26b’s metallicity. Astronomers calculate the metallicity, an indication of how rich the planet is in all elements heavier than hydrogen and helium, because it gives them clues about how a planet formed. To compare planets by their metallicities, scientists use the Sun as a point of reference, almost like describing how much caffeine beverages have by comparing them to a cup of coffee. Jupiter has a metallicity about 2 to 5 times that of the Sun. For Saturn, it’s about 10 times as much as the Sun. These relatively low values mean that the two gas giants are made almost entirely of hydrogen and helium.

The ice giants Neptune and Uranus are smaller than the gas giants but richer in the heavier elements, with metallicities of about 100 times that of the Sun. So, for the four outer planets in our solar system, the trend is that the metallicities are lower for the bigger planets. Scientists think this happened because, as the solar system was taking shape, Neptune and Uranus formed in a region toward the outskirts of the enormous disk of dust, gas, and debris that swirled around the immature Sun. Summing up the complicated process of planetary formation in a nutshell: Neptune and Uranus would have been bombarded with a lot of icy debris that was rich in heavier elements. Jupiter and Saturn, which formed in a warmer part of the disk, would have encountered less of the icy debris.

Two planets beyond our solar system also fit this trend. One is the Neptune-mass planet HAT-P-11b. The other is WASP-43b, a gas giant twice as massive as Jupiter.

Wakeford and her colleagues found that HAT-P-26b bucks the trend. They determined its metallicity is only about 4.8 times that of the Sun, much closer to the value for Jupiter than for Neptune. “This analysis shows that there is a lot more diversity in the atmospheres of these exoplanets than we were expecting, which is providing insight into how planets can form and evolve differently than in our solar system,” said David K. Sing of the University of Exeter and the second author of the paper. “I would say that has been a theme in the studies of exoplanets: Researchers keep finding surprising diversity.”

Meeting HIghlights

48th Lunar and Planetary Science Conference

March 20-24, 2017

The Woodlands, Texas

The 48th Lunar and Planetary Science Conference (LPSC) was held in March at The Woodlands Waterway Marriott Hotel and Convention Center in The Woodlands, Texas, and was co-chaired by Louise Prockter of the Lunar and Planetary Institute and Eileen Stansbery of the NASA Johnson Space Center. Attendance was high, with 1792 attendees (up 4% from 2016) from 33 countries. Submitted abstract numbers were also high, with 2046 abstracts submitted from 41 countries. LPSC continues to be accessible and important to young scientists, with student participation at more than 30% of total attendance. Meeting organization was provided by the Lunar and Planetary Institute (LPI).

LPSC began with Sunday evening registration and a very successful welcome event, which gave participants an opportunity to connect with friends and colleagues. On Monday morning, the oral sessions began. The conference featured four-and-a-half days of sessions, featuring such topics as lunar volcanism; Mars atmosphere; giant and late accretion impacts; chondrules, metals, sulfides, and chromites; geologic mapping; impact cratering processes; topics in advanced curation; and many more. Special sessions included Mars Volatile Surface-Atmospheric Interactions: Past and Present; Large Igneous Provinces in the Solar System; and IODP-ICDP Expedition 364 to the Chicxulub Impact Crater. The complete program and abstracts are available at https://www.hou.usra.edu/meetings/lpsc2017/.

Jim Green of NASA’s Planetary Science Division addressed the planetary science community during the Monday evening NASA Headquarters Briefing.

Dr. David Smith presented this year’s Masursky Lecture.

Fun at the LPI green screen!

Hidden Figures movie night.

48th LPSC Microbloggers.

The plenary session on Monday afternoon featured the Masursky Lecture, “Planetary Topography from Laser Altimetry,” by Dr. David Smith of the Massachusetts Institute of Technology. The winners of the 2016 Dwornik Awards and 2017 LPI Career Development Awards were also recognized. During the Monday evening NASA Headquarters Briefing, representatives from the Planetary Science Division of NASA’s Science Mission Directorate addressed meeting attendees.

Poster sessions held on Tuesday and Thursday evening included the same topics covered in the oral sessions, as well as topics such as education and public outreach, material and environmental analogs, planetary mission concepts, and instrument and payload concepts. A number of exhibitors were present, featuring demonstrations, the latest planetary science publications, and information about student opportunities in planetary science.

Wednesday evening also featured a free showing of the film Hidden Figures, sponsored by the Universities Space Research Association. The evening was yet another opportunity for participants to network in a relaxed environment. Other networking opportunities included new technology demonstrations of LPI’s virtual reality, augmented reality, and the green screen.

In addition to the oral sessions, there were many peripheral meetings and activities held during the week, including an educational engagement opportunity (Planetary Science Palooza), a Europa Lander workshop, a workshop for early career scientists on publishing scientific papers, and a town hall with the LPSC co-chairs.

As in previous years, the conference engaged LPSC Microbloggers to use social media to provide real-time coverage of the science presented during the sessions. Combined with a Twitter feed on the meeting website, this coverage allowed participants to know what was going on in the sessions they were unable to attend and also provided information for those in other parts of the world who were not able to make it to the meeting.

Plans are already underway for the 49th LPSC, which is scheduled for March 19–23, 2018. Mark your calendars! Details will be made available on the meeting website soon (https://www.hou.usra.edu/meetings/lpsc2018/).

Workshop on Chondrules and the Protoplanetary Disk

February 27–28, 2017

London, United Kingdom

Chondrules are silicate rich rounded inclusions common in most chondrite groups. They were clearly once molten or partly molten droplets, produced in the earliest times of solar system formation. However, despite extensive study, their origin has remained enigmatic.

The Workshop on Chondrules and the Protoplanetary Disk was held on February 27–28, 2017, at the Natural History Museum in London, United Kingdom, and was organized by Sara Russell, Harold Connolly, and Sasha Krot. Ninety-two students and professionals attended the workshop, which was split into four sessions: Chondrule Precursors and Relationship to Matrix; Chronology; Thermal History and Environment of Formation; and Chondrule-Forming Mechanisms. In addition, a poster session was held on the first evening of the workshop on topics covering all aspects of the theme. The detailed program and abstracts are available on the workshop website at https://www.hou.usra.edu/meetings/chondrules2017/.

The first three sessions had the aim of identifying the critical constraints on chondrule formation, and the final session was a synthesis of the various formation mechanisms that have been described in the literature. The mechanisms discussed included formation by nebular shocks, by planetesimal collisions, by lightning, and flybys of planetesimals with magma oceans.

The workshop provided the opportunity for plenty of discussion, and while there was no consensus on how these objects formed, the workshop identified important new avenues for research that will help solve this intransient issue. A book based on the proceedings of the workshop will be published by Cambridge University Press in 2018 as part of their Planetary Science Series.

Spotlight on Education

“Spotlight on Education” highlights events and programs that provide opportunities for planetary scientists to become involved in education and public engagement. If you know of space science educational programs or events that should be included, please contact the Lunar and Planetary Institute’s Education Department at education@lpi.usra.edu.

Upcoming Public Event Opportunities

Upcoming opportunities exist for educator and public engagement around the broader topics of NASA planetary exploration. Consider getting in touch with local astronomical societies, planetariums and museums, local scientists, and NASA’s Solar System Ambassadors (http://solarsystem.nasa.gov/ssa/directory.cfm) — ask them to join your events and share their experiences or resources with your audience.

2017 Eclipse Across America

This summer, a total eclipse of the Sun will be visible from the U.S. The path of the total eclipse is only about 70 miles wide, beginning in Oregon and ending in South Carolina. A partial eclipse will be visible to 500 million people in the other parts of the US and North America. For more information, visit https://eclipse2017.nasa.gov.

NASA welcomes scientists, engineers, science writers, amateur astronomers, and science educators to sign up as Subject Matter Experts. Groups seeking an expert speaker can reach out to you to join their event. Visit https://eclipse2017.nasa.gov/subject-matter-experts for more information.

Radio station WGBH in Boston, Massachusetts, has created eclipse materials, including a teacher toolkit, to support educators in planning and integrating the eclipse into the classroom. These materials are available at http://bit.ly/TeachEclipse2017.

In the spring 2017 edition of the Astronomical Society of the Pacific’s “The Universe in the Classroom,” learn about a storyline approach to teaching about eclipses, including investigations into lunar phases, the size and scale of the Earth-Moon system, why eclipses happen, and the pattern and frequency of their occurrence. Visit https://www.astrosociety.org/publications/universe-in-the-classroom.

Cassini Grand Finale, September 15, 2017

After almost 20 years in space, NASA’s Cassini spacecraft begins the final chapter of its remarkable story of exploration: its Grand Finale (see related feature story in this issue). Hold an event to say goodbye to Cassini at your institution or a nearby community facility such as a school or public library. Find ideas for event activities at https://saturn.jpl.nasa.gov/mission/grand-finale/overview and search for a local astronomy club through the Night Sky Network (https://nightsky.jpl.nasa.gov) to provide telescopes. Saturn will make a fantastic telescopic target the evening of September 15.

International Observe the Moon Night, October 28, 2017

After celebrating the August solar eclipse, why not give the Moon its own night? Join lunar enthusiasts from around the globe to celebrate International Observe the Moon Night. Learn about the event, get activity ideas, and register your event at http://observethemoonnight.org.

LPI Augmented Reality (AR) App

The Lunar and Planetary Institute has created an augmented reality (AR) app you can use to take an interactive tour of objects in the solar system, including the Moon, Mars, Europa, and Pluto. Download and launch the “lunar and planetARy” app, and point your camera at an interactive poster (available online to view or print). Available through Google Play and the App Store. Links to the app and the posters are available at http://www.lpi.usra.edu/AR/.

New “Explore NASA Science” Website

Explore the redesigned NASA Science website at https://science.nasa.gov and learn about new discoveries, sign up for the newsletter, and much more!

Citizen Science: Help NASA Find “Planet Nine”

Backyard Worlds: Planet 9 is a new site for members of the general public to assist with the search for Planet Nine, as well as other possible celestial bodies between the orbit of Neptune and the closest star. Visit https://www.zooniverse.org/projects/marckuchner/backyard-worlds-planet-9.

NASA Postdoctoral Program Fellowships

The NASA Postdoctoral Program (NPP) supports NASA’s goal to expand scientific understanding of Earth and the universe in which we live. Selected by a competitive peer-review process, NPP fellows complete one- to three-year fellowships that offer scientists and engineers unique opportunities to conduct research in fields of science relevant to NASA. These opportunities advance NASA’s missions in Earth science, heliophysics, planetary science, astrophysics, space bioscience, aeronautics and engineering, human exploration and space operations, and astrobiology. Opportunities are available at NASA centers and other NASA-approved sites. Interested applicants may apply by one of three annual application deadlines: March 1, July 1, and November 1. For more information, visit https://npp.usra.edu.

Eugene Shoemaker Impact Cratering Award

The Eugene M. Shoemaker Impact Cratering Award is for undergraduate or graduate students, of any nationality, working in any country, in the disciplines of geology, geophysics, geochemistry, astronomy, or biology. The award, which will include $2500, is to be applied for the study of impact craters, either on Earth or on the other solid bodies in the solar system; areas of study may include (but are not necessarily limited to) impact cratering processes; the bodies that make the impacts; or the geological, chemical, or biological results of impact cratering.

The application deadline is August 25, 2017. For more information, and to access the application form, visit http://www.lpi.usra.edu/science/kring/Awards/Shoemaker_Award.

American Astronomical Society Education Prize

The American Astronomical Society (AAS) Education Prize is to recognize outstanding contributions to the education of the public, students, and/or the next generation of professional astronomers. Nominations and letters of support for the AAS prizes for 2017 must arrive in the Secretary’s office by June 30, 2017. For more information, visit http://aas.org/grants-and-prizes/prize-nominations.

In Memoriam

Tobias C. Owen, 1936–2017

Credit: NASA.

Tobias (Toby) C. Owen died on March 4, 2017, in Sacramento, California, where he had been living since his retirement from the University of Hawaii’s Institute for Astronomy in 2012. Owen’s career as a planetary scientist started at the beginning of the exploration of the solar system with spacecraft, and he was actively involved in the Juno mission at the end.

Owen grew up in Denver, Colorado, and Santa Fe, New Mexico. He developed an interest in astronomy at an early age and went on to the University of Chicago to earn his B.S. and M.S. degrees in physics. He then enrolled in the newly formed Lunar and Planetary Laboratory (LPL) at the University of Arizona, becoming one of the first students of Gerard Kuiper, and obtaining his Ph.D. in 1965 on spectroscopic studies of Mars, Jupiter, and Saturn. Owen joined the faculty at the State University of New York (SUNY) at Stony Brook, where he was a professor for many years, and then joined the faculty at the University of Hawaii, where he was affiliated until his passing.

Owen’s earliest work was in spectroscopy of the giant planets, and this interest quickly broadened to encompass all aspects of the origin and evolution of planetary atmospheres. With a special interest in isotopic abundances, he pursued and promoted a wide range of observational and theoretical investigations toward understanding the origins of all the planets and small bodies of the solar system. As one of the world’s leading planetary scientists, he was an active participant in a great number of missions, including Apollo 15 and 16, Viking, Voyager, Galileo, Rosetta, Juno, and Cassini-Huygens. He played a leading role in the development of the Cassini-Huygens mission as a joint project of NASA and ESA, and was called upon frequently to promote this and other missions to funding agencies in Europe as well as to NASA. Owen had close ties with European colleagues, notably in France, where he inspired a vigorous planetary group at the Paris Observatory.

Along with his scientific endeavors, Owen collaborated with Frank Drake and Carl Sagan to initiate an effort in 1968 to form a specialized society in planetary studies. Acting on a suggestion from Juan Oro, and with the support of several planetary specialists at Kitt Peak National Observatory, their efforts ultimately led to the formation of the AAS Division of Planetary Sciences (DPS).

With the passing of Owen, science has lost a great talent, a valued colleague, and to many in the U.S. and abroad, a close friend. He will be remembered as a man of the world, unfailingly generous and modest, and a great scientist. He inspired all of his many colleagues with his enthusiasm for all aspects of planetary science, including the big questions of the origin of the solar system and of life in the universe. Among the many honors and accolades he received, Owen was awarded the Gerard P. Kuiper Prize of the DPS in 2009.

— Portions of text courtesy of the Institute for Astronomy, University of Hawaii, and the Division of Planetary Sciences

Nathan Bridges, 1966–2017

Credit: JHU/APL.

Nathan Bridges, a planetary research scientist at the Johns Hopkins University Applied Physics Laboratory (APL), passed away on April 26 at the age of 50.

While an undergraduate student at the University of Colorado, Bridges was selected as a member of the Lunar and Planetary Institute’s summer intern program in 1988. He then went on to earn a B.A. in geology from the University of Colorado in 1989, an M.S. in geology from Arizona State University in 1992, and a Ph.D. in geology from the University of Massachusetts in 1997. He spent 12 years at NASA’s Jet Propulsion Laboratory in Pasadena, California, before joining APL’s Planetary Exploration (SRE) Group in 2009.

Bridges was a senior expert on the geology of Mars, remote sensing techniques, and the role of wind-driven processes in planetary erosion and sedimentation on Earth, Mars, and Titan, Saturn’s largest moon. Among his many important findings, Bridges discovered that wind is as important a geologic process on Mars as it is on Earth, despite the much lower density of the martian atmosphere.

He was an integral part of multiple Mars missions and instrument teams, serving as a Co-Investigator on the High Resolution Imaging Science Experiment (HiRISE) instrument on the Mars Reconnaissance Orbiter; a Co-Investigator on the Mars Science Laboratory (Curiosity rover) ChemCam instrument; and a science team member on two Mars-2020 rover instruments, SuperCam and the Mars Environmental Dynamics Analyzer.

Bridges was also an associate research professor in the Department of Earth and Planetary Sciences at Johns Hopkins University, where he taught a class and advised graduate students. Additionally, he took leadership roles in the international planetary science community. For example, he served as editor of the American Geophysical Union publication EOS, as secretary of the AGU Planetary Science Section, as guest editor of several special issues of the journal Icarus, and on numerous NASA panels and advisory committees.

Bridges developed research collaborations with colleagues from around the world. His work included field studies at dune fields on Earth, experiments in wind tunnels to simulate conditions on other planets, and analysis of data from spacecraft observations.

To those who knew Bridges personally, his loss is a profound shock; he was a wonderful friend, mentor, and colleague to all. His friendship and camaraderie made it a joy to work with him — he truly saw science as a collaborative, rather than competitive, effort. He will be dearly missed by friends and colleagues across the world. A tribute to Bridges from the Planetary Society, of which he was a member since 1980, can be read at http://www.planetary.org/blogs/casey-dreier/2017/0503-a-tribute-to-nathan-bridges.html.

— Portions of text courtesy of The Johns Hopkins University Applied Physics Laboratory

Michael F. A’Hearn, 1940–2017

Credit: University of Central Florida.

Michael Francis A’Hearn, an astronomer and Distinguished Professor at the University of Maryland, passed away on May 29 at the age of 76 at his home in University Park, Maryland. A’Hearn led NASA’s Deep Impact mission, the first man-made object to impact the nucleus of a comet to study its composition, and was also the principal investigator for NASA’s EPOXI mission and the leader of the Small Bodies Node of NASA’s Planetary Data System.

A’Hearn received his B.A. in science at Boston College and his Ph.D. in astronomy at the University of Wisconsin–Madison. His studies focused on comets as well as asteroids, and he supervised numerous graduate students. He aided in the development of systems for surveying abundances in comets as well as techniques for determining the sizes of cometary nuclei that used optical and infrared measurements.

A’Hearn was an elected fellow of the American Association for the Advancement of Science (AAAS), and authored more than 100 papers published in scientific journals. He was honored for his significant contributions to the understanding of comets with both the Kuiper Prize and the Space Science Award, two of the most prestigious awards offered by professional societies. In June 1986, the main-belt asteroid 3192 A’Hearn, discovered by American astronomer Edward Bowell at Lowell’s Anderson Mesa Station in Flagstaff, Arizona, was named after him in honor of his contributions to cometary science.

A’Hearn’s deep love of science and gregarious nature led to his ability to make a positive difference in whatever task he took on. In addition to his professional accomplishments, A’Hearn was also an avid sailor who had a commercial coast guard license. He was also heavily involved with community outreach projects designed to make a difference in the lives of those less fortunate than himself, and his family has requested that memorial contributions be made to S.O.M.E. (So Others Might Eat), 71 O Street NW, Washington, DC 20001 (http://www.some.org) or Catholic Relief Services, P.O. Box 17090, Baltimore, MD 21297 (http://www.crs.org).

— Portions of text courtesy of the Division of Planetary Sciences and the University of Maryland

Milestones

Prockter Honored with 2017 Harold Masursky Award

Louise M. Prockter, Director of the Lunar and Planetary Institute (LPI), has received the prestigious Harold Masursky Award for meritorious service to planetary science, presented by the American Astronomical Society’s Division for Planetary Sciences (DPS).

The Masursky Award was established by the DPS to recognize and honor individuals who have rendered outstanding service to planetary science and exploration through engineering, managerial, programmatic, or public service activities.

Prockter has made valuable contributions by participating in and leading community efforts to plan and evaluate missions and science priorities. She has worked tirelessly on behalf of the planetary science community on science definition teams, National Research Council boards, and NASA committees. Her efforts have helped shape modern planetary science, as exemplified by her leadership on a recent study of the utility of mission Participating Scientist programs. By setting up support groups and mentoring female scientists, Prockter ensured faster development of early career scientists who have made strong contributions to the field. Her emphasis on thinking of planetary science as a whole when choosing to serve highlights the value of working on behalf of all.

Wang Appointed to Head NASA’s Office of Communications

Jen Rae Wang has been selected by Acting Administrator Robert Lightfoot as NASA’s Associate Administrator for the Office of Communications. Wang joins NASA with more than a decade of experience at the highest levels of state and federal government in public, legislative, and media affairs both domestically and internationally, strategic communications, as well as small and large-scale organizational executive leadership.

“We’re pleased to welcome Jen Rae to NASA,” said Lightfoot from Headquarters in Washington. “Her experience in government and journalism and enthusiasm for our work are going to be immensely useful in engaging wide audiences with the challenging missions of the future.”

At NASA, Wang will direct internal and external communications for the agency and serve as a Senior Advisor to NASA’s Administrator and other executive leaders. She is responsible for managing an agency-wide staff of more than 100 that implements all aspects of NASA’s external and internal communications.

SSERVI Announces 2017 Award Winners

Recognizing that science and exploration go hand in hand, NASA created the Solar System Exploration Research Virtual Institute (SSERVI) in 2013, expanding the scope of the former NASA Lunar Science Institute to include basic and applied scientific research on the Moon, near-Earth asteroids, and the martian moons Phobos and Deimos. The Eugene Shoemaker medal, Michael J. Wargo Award, and Susan Mahan Niebur award recognize outstanding achievement in exploration science. The winners are nominated by their academic peers and selected by SSERVI Director Yvonne Pendleton. The awards will be presented along with invited lectures from the recipients at the 2017 Exploration Science Forum (ESF), which will take place July 18–20 at the NASA Research Park at NASA Ames Research Center in Moffett Field, California.

Shoemaker Prize —

The 2017 Shoemaker Distinguished Scientist Medal, named after American geologist and one of the founders of planetary science, Eugene Shoemaker, is awarded to Maria Zuber at the Massachusetts Institute of Technology for her significant scientific contributions throughout the course of her career. The award includes a certificate and medal with the Shakespearian quote, “And he will make the face of heaven so fine, that all the world will be in love with night.”

Zuber’s research focuses on the structure and tectonics of solid solar system objects. She specializes in using gravity and laser altimetry measurements to determine interior structure and evolution and has been involved in more than a half-dozen NASA planetary missions aimed at mapping the Moon, Mars, and Mercury, as well as several asteroids. She was principal investigator for the Gravity Recovery and Interior Laboratory (GRAIL) mission and as such became the first woman to lead a NASA spacecraft mission.

Michael J. Wargo Award —

The Michael J. Wargo Award is an annual award given to a scientist or engineer who has significantly contributed to the integration of exploration and planetary science throughout their career. The 2017 Michael J. Wargo Award is given to Lawrence (Larry) Taylor at the Planetary Geosciences Institute of the University of Tennessee, Knoxville.

Taylor has studied lunar rocks and soils continuously since the days of the Apollo 11 mission, and even participated in advising the Apollo astronauts during their extravehicular activities on the Moon. His studies of the chemical, physical, and geotechnical properties of lunar regolith have led to several significant geotechnical discoveries on in situ resource utilization of lunar materials for establishment of a lunar settlement. More recently, his efforts have expanded into meteorites as many new lunar and martian meteorites found in the Antarctic and equatorial hot deserts have provided renewed interest and excitement for these heavenly bodies. His zeal for a human return to the Moon goes unabated.

Susan Mahan Niebur Early Career Award —

The Susan Mahan Niebur Early Career Award is an annual award given to an early career scientist who has made significant contributions to the science or exploration communities. Recipients of the Susan M. Niebur Early Career Award are researchers who are no more than 10 years from receiving their Ph.D. and have shown excellence in their field and demonstrated meaningful contributions to the science or exploration communities. This year the prize is presented to two outstanding scientists, Adrienne Dove at the University of Central Florida, and Samuel Lawrence at the Astromaterials Research and Exploration Science Division at NASA’s Johnson Space Center.

Dove’s research focuses on planetary sciences and dusty plasmas in the solar system. Her laboratory research on microgravity and dusty plasmas, collisions, and planet formation is helping resolve fundamental mechanisms of dust charging and transport, which have been puzzling scientists for decades.

Lawrence is an expert in exploration science and extraterrestrial materials, a Co-Investigator on the Lunar Reconnaissance Orbiter Camera science team, and an active member of the Executive Committee of the Lunar Exploration Analysis Group, working to enable human exploration of the Moon and other destinations.

NASA Announces Astronomy and Astrophysics Fellows for 2017

NASA has selected 28 fellows for its prestigious Einstein, Hubble, and Sagan fellowships. Each post-doctoral fellowship provides three years of support to awardees to pursue independent research in astronomy and astrophysics. The new fellows will begin their programs in the fall of 2017 at a host university or research center of their choosing in the United States.

Participants in the Einstein Fellowship program conduct research broadly related to the mission of NASA’s Physics of the Cosmos (PCOS) program, which aims to expand our knowledge of the origin, evolution and fate of the universe. The PCOS program consists of a suite of operating science missions and possible future missions that focus on specific aspects of these questions.

The eight new Einstein Fellows and their host institutions are Vivienne Baldassare, Yale University; Jennifer Barnes, undecided; Rahul Kannan, Smithsonian Astrophysical Observatory; Philip Mocz, Princeton University; Alexander Philippov, University of California, Berkeley; Anna Rosen, Harvard University; Zachary Slepian, Lawrence Berkeley National Laboratory; andKrista Smith, Kavli Institute for Particle Astrophysics and Cosmology.

Participants in the Hubble Fellowship program conduct research broadly related to the mission of NASA’s Cosmic Origins (COR) program, which aims to examine the origins of galaxies, stars, and planetary systems, and the evolution of these structures with cosmic time. The COR program consists of a suite of operating science missions and possible future missions that focus on specific aspects of these questions.

Each year, the current Hubble Fellows convene for a three-day symposium to present results of their recent research and to meet with other Hubble Fellows and the scientific and administrative staff who manage the program for NASA. The 2017 symposium was held in Baltimore on March 13–15.

The 17 new Hubble Fellows are Rachael Beaton, Princeton University; Ivan Cabrera Ziri Castro, Harvard College Observatory; Ena Choi, Columbia University; Susan Clark, Institute for Advanced Study; Wen-fai Fong, University of Arizona; Katheryn Decker French, Carnegie Observatories; Anne Jaskot, University of Massachusetts; Alexander Ji, Carnegie Observatories; Sebastiaan Krijt, University of Chicago; Sarah Loebman, University of California, Davis; Brett McGuire, National Radio Astronomy Observatory; Evan Schneider, Princeton University; Jordan Stone, University of Arizona; Johanna Teske, Carnegie Institution; Siyao Xu, University of Wisconsin – Madison; Ke Zhang, University of Michigan; and George Zhou, Smithsonian Astrophysical Observatory;

The Sagan Fellowship supports scientists whose research is aligned with NASA’s Exoplanet Exploration program. The primary goal of this program is to discover and characterize planetary systems and Earth-like planets around other stars. The current and past Sagan Fellows will meet in Pasadena, California, at the Sagan Fellows Symposium later this year to take advantage of networking opportunities and update their peers on their research efforts.

The 2017 Sagan Fellows are Raphaelle Haywood, Harvard College Observatory; Benjamin Pope, New York University; and Andrew Vanderburg, University of Texas, Austin.

Congratulations to all these awardees!

Student Poster Competition Winners at AbSciCon 2017

From left to right: Jacqueline Long, Marcus Bray, and Vincent Riggi

The NASA Astrobiology Institute was pleased to sponsor once again the Student Poster Competition at the Astrobiology Science Conference (AbSciCon) 2017. As with previous AbSciCon conferences, this event provided motivation, encouragement, and most of all, recognition to astrobiologists of the future. Thank you to the 85 students and 43 judges who participated in the competition!

First place, with an award of $1000, was given to Jacqueline Long from the College of Marine Science, University of South Florida. Her poster was entitled, “Chlorophyll-f: Earth’s Unseen Production and Habitability Under Red Light.”

Second place, with an award of $750, was given to Marcus Bray from the School of Biology, Georgia Institute of Technology. His poster was entitled, “Bacterial Ribosomes Incorporate Iron Under Pre-GOE Conditions.”

Third place, with an award of $500, was given to Vincent Riggi from the Department of Earth and Environmental Sciences, Rensselaer Polytechnic Institute. His poster was entitled, “Abiotic Catalysis of RNA Polymerization in Aqueous Metal Chloride Solutions.”

NASA Communications Honored with 2017 Webby Awards

NASA’s digital communications team was honored at the 21st Annual Webby Awards on May 16 in New York. For the first time, NASA’s social media presence was recognized by the Webby Awards, winning in corporate communications and being honored with the People’s Voice Award.

NASA’s Cassini project was recognized with its second Webby for science websites. NASA.gov, the agency’s primary website, received its ninth People’s Voice Award in the Government and Civil Innovation category. The agency’s Jet Propulsion Laboratory social media team in Pasadena, California, was nominated in the Education and Discovery category, and the Cassini social media team was nominated for the Best Overall Social Presence category.

“First and foremost, a sincere ‘thank you’ to our NASA friends and fans for their support,” said NASA’s Associate Administrator for Communications, Jen Rae Wang. “We value [your] interest and support of exploration and discovery. We’re very happy to see NASA’s digital communications efforts honored with Webby Awards. As our NASA fan community turns more to the web and social media for news, they will find NASA there for them.”

Established in 1996 by the International Academy of Digital Arts and Sciences, the Webby Awards honor excellence on the Internet, including websites, advertising and media, online film and video, mobile sites, apps, and social media.

NASA Invests in 22 Visionary Exploration Concepts

JPL’s AREE rover for Venus is just one of the concepts selected by NASA for further research funding. Credit: NASA/JPL-Caltech.

A mechanical rover inspired by a Dutch artist and a weather balloon that recharges its batteries in the clouds of Venus — these are just two of the five ideas that originated at NASA’s Jet Propulsion Laboratory in Pasadena, California, and are advancing for a new round of research funded by the agency. In total, the space agency is investing in 22 early-stage technology proposals that have the potential to transform future human and robotic exploration missions, introduce new exploration capabilities, and significantly improve current approaches to building and operating aerospace systems.

The 2017 NASA Innovative Advanced Concepts (NIAC) portfolio of Phase I concepts covers a wide range of innovations selected for their potential to revolutionize future space exploration. Phase I awards are valued at approximately $125,000 for nine months to support initial definition and analysis of their concepts. If these basic feasibility studies are successful, awardees can apply for Phase II awards.

The selected 2017 Phase I proposals are:

- A Synthetic Biology Architecture to Detoxify and Enrich Mars Soil for Agriculture, Adam Arkin, University of California, Berkeley

- A Breakthrough Propulsion Architecture for Interstellar Precursor Missions, John Brophy, NASA’s Jet Propulsion Laboratory (JPL), Pasadena, California

- Evacuated Airship for Mars Missions, John-Paul Clarke, Georgia Institute of Technology, Atlanta

- Mach Effects for In Space Propulsion: Interstellar Mission, Heidi Fearn, Space Studies Institute, Mojave, California

- Pluto Hop, Skip, and Jump, Benjamin Goldman, Global Aerospace Corporation, Irwindale, California

- Turbolift, Jason Gruber, Innovative Medical Solutions Group, Tampa, Florida

- Phobos L1 Operational Tether Experiment, Kevin Kempton, NASA’s Langley Research Center, Hampton, Virginia

- Gradient Field Imploding Liner Fusion Propulsion System, Michael LaPointe, NASA’s Marshall Space Flight Center, Huntsville, Alabama

- Massively Expanded NEA Accessibility via Microwave-Sintered Aerobrakes, John Lewis, Deep Space Industries, Inc., Moffett Field, California

- Dismantling Rubble Pile Asteroids with Area-of-Effect Soft-bots, Jay McMahon, University of Colorado, Boulder

- Continuous Electrode Inertial Electrostatic Confinement Fusion, Raymond Sedwick, University of Maryland, College Park

- Sutter: Breakthrough Telescope Innovation for Asteroid Survey Missions to Start a Gold Rush in Space, Joel Sercel, TransAstra, Lake View Terrace, California

- Direct Multipixel Imaging and Spectroscopy of an Exoplanet with a Solar Gravity Lens Mission, Slava Turyshev, JPL

- Solar Surfing, Robert Youngquist, NASA’s Kennedy Space Center, Florida

- A Direct Probe of Dark Energy Interactions with a Solar System Laboratory, Nan Yu, JPL

Awards under Phase II of the NIAC program can be worth as much as $500,000 for two-year studies and allow proposers to further develop Phase I concepts that successfully demonstrated initial feasibility and benefit.

The selected 2017 Phase II proposals are:

- Venus Interior Probe Using In-Situ Power and Propulsion, Ratnakumar Bugga, JPL

- Remote Laser Evaporative Molecular Absorption Spectroscopy Sensor System, Gary Hughes, California Polytechnic State University, San Luis Obispo, California

- Brane Craft Phase II, Siegfried Janson, The Aerospace Corporation, El Segundo, California

- Stellar Echo Imaging of Exoplanets, Chris Mann, Nanohmics, Inc., Austin, Texas

- Automaton Rover for Extreme Environments, Jonathan Sauder, JPL

- Optical Mining of Asteroids, Moons, and Planets to Enable Sustainable Human Exploration and Space Industrialization, Joel Sercel, TransAstra Corp.

- Fusion-Enabled Pluto Orbiter and Lander, Stephanie Thomas, Princeton Satellite Systems, Inc., Plainsboro, New Jersey

NASA selected these projects through a peer-review process that evaluated innovativeness and technical viability. All projects are still in the early stages of development, most requiring 10 or more years of concept maturation and technology development before use on a NASA mission.

NASA Launches App for Amazon Fire TV

NASA has released its popular app for a new platform, Amazon Fire TV. The public can browse NASA’s amazing discoveries directly from their personal devices.

NASA has released its popular app for a new platform, Amazon Fire TV. This version joins previous releases of the app for iOS, Android, and Apple TV devices. “With the NASA app, the public can browse NASA’s amazing discoveries directly from their personal devices,” said Bob Jacobs, the deputy associate administrator for Communications at the agency’s Headquarters in Washington. “Today, users with Amazon Fire TV and other services can explore NASA’s wealth of images, videos and more on their home televisions.”

The NASA app for Amazon Fire TV offers several features for users, including:

- Watch live-streaming NASA Television

- Get a real-time view of Earth from the International Space Station

- View more than 16,000 images, either individually or as a slideshow

- Play more than 14,000 on-demand NASA videos

- Learn more about NASA’s current missions

“We are always looking for new and exciting ways to bring NASA to the public,” said Eugene Tu, center director at NASA’s Ames Research Center in Silicon Valley, where NASA apps are developed. The NASA app is available for free in the app store on the Amazon Fire TV.

New and Noteworthy

Note: Product descriptions are taken from the publisher’s website. LPI is not responsible for factual content.

BOOKS

Planetesimals: Early Differentiation and Consequences for Planets.

Edited by Linda T. Elkins-Tanton and Benjamin P. Weiss. Cambridge University Press. 2017, 448 pp., Hardcover, $140.00. www.cambridge.org

Processes governing the evolution of planetesimals are critical to understanding how rocky planets are formed, how water is delivered to them, the origin of planetary atmospheres, how cores and magnetic dynamos develop, and ultimately, which planets have the potential to be habitable. Theoretical advances and new data from asteroid and meteorite observations, coupled with spacecraft missions such as Rosetta and Dawn, have led to major advances in this field over the last decade. This transdisciplinary volume presents an authoritative overview of the latest in our understanding of the processes of planet formation. Combining meteorite, asteroid, and icy body observations with theory and modelling of accretion and orbital dynamics, this text also provides insights into the exoplanetary system and the search for habitable worlds. This is an essential reference for those interested in planetary formation, solar system dynamics, exoplanets, and planetary habitability.

Worlds Fantastic, Worlds Familiar: A Guided Tour of the Solar System.

By Bonnie J. Buratti. Cambridge University Press, 2017, 250 pp., Hardcover, $29.99. www.cambridge.org

Join Buratti, a leading planetary astronomer, on this personal tour of NASA’s latest discoveries. Moving through the solar system from Mercury, Venus, Mars, past comets and asteroids and the moons of the giant planets, to Pluto, and on to exoplanets, she gives vivid descriptions of landforms that are similar to those found on Earth but that are more fantastic. Sulfur-rich volcanos and lakes on Io, active gullies on Mars, huge ice plumes and tar-like deposits on the moons of Saturn, hydrocarbon rivers and lakes on Titan, and nitrogen glaciers on Pluto are just some of the marvels that await readers. Discover what it is like to be involved in a major scientific enterprise, with all its pitfalls and excitement, from the perspective of a female scientist. This engaging account of modern space exploration is written for non-specialist readers, from students in high school to enthusiasts of all ages.

Apollo: The Panoramas.

By Mike Constantine. Moonpans.com Ltd., 2015, 130 pp., Hardcover, $65.00. www.moonpans.com

Having spent the last 15 years assembling high-resolution, seamless panoramas from the Apollo missions, the author has compiled more than 50 stunning panoramas into one book, Apollo: The Panoramas. Each panorama spans a full 28 × 10.25-inch double-page spread, and the book includes almost every panorama captured on the lunar surface, as well as panoramic images captured from the lunar module windows and the stand-up extravehicular activity (EVA) on Apollo 15. Each panorama has a detailed description by the author, and most also have exclusive comments from the Apollo moonwalkers who were actually there, including Alan Bean, Edgar Mitchell, Charlie Duke, and Harrison Schmitt.

Mars: The Pristine Beauty of the Red Planet.

By Alfred S. McEwen, Candice Hansen-Koharcheck, and Ari Espinoza. University of Arizona Press, 2017, 448 pp., Hardcover, $75.00. www.uapress.arizona.edu

The High Resolution Imaging Science Experiment (HiRISE) camera is the most powerful camera ever sent to another planet, showing us Mars in astonishing detail. Featuring an outstanding and never-before-published collection of HiRISE high-resolution color images with explanatory captions in 24 languages, this book offers a unique volume produced from an active NASA mission. Mars enthusiasts will appreciate these perfect snapshots of our current understanding of Mars, with soon-to-be classic pictures that have come to define our vision of the Red Planet. These images and their interpretations will be held as a yardstick for future exploration as we learn more about the surface and geologic processes of Mars. With tantalizing and artistic glimpses at actively eroding slopes, impact craters, strange polar landscapes, avalanches, and even spectacular descent pictures of probes like the Phoenix Lander and the Mars Science Laboratory, we see what researchers are seeing. Through vivid and beautiful images, this book underscores the need for such a camera on future orbiters, especially as more landing missions are planned. Mars: The Pristine Beauty of the Red Planet provides a stunning keepsake of one of humanity’s greatest accomplishments in space travel.

Chicxulub: The Impact and Tsunami: The Story of the Largest Known Asteroid to Hit the Earth.

By David Shonting and Cathy Ezrailson. Springer. 2017, 124 pp., Hardcover, $29.99. www.springer.com

This book tells the story of the catastrophic impact of the giant 10-kilometer asteroid Chicxulub into the ancient Gulf of Mexico 65.5 million years ago, beginning with a discussion of the nature of asteroids and the likelihood of future Earth impacts. The story then turns to the discovery of a global sediment layer attributed to the fallout from the impact and a piecing together of the evidence that revealed a monster crater, buried under the Gulf. Reviewed is the myriad geological and fossil evidence that suggested the disastrous sequence of events occurring when a “nuclear-like” explosion ripped through the sea, Earth, and atmosphere, thus forming the mega-crater and tsunami. The aftermath of the Chicxulub event initiated decades and more of major global climate changes, including a “nuclear winter” of freezing darkness and blistering greenhouse warming. A chapter is dedicated to the science of tsunamis and their model generation, including a portrayal of the globally rampaging Chicxulub waves. The asteroid’s global devastation killed off some 70% of animal and plant life, including the dinosaurs. The study of an ancient Cambrian fossil bed suggests how “roll of the dice” events can affect the future evolution of life on Earth. We see how Chicxulub’s apparent destruction of the dinosaurs, followed by their replacement with small mammals, altered forever the progress of human evolution. This book presents a fascinating glimpse through the lens of the natural sciences — the geology, climatology, and oceanography of the effects of an enormous astronomical event.

Origins of the Earth, Moon, and Life: An Interdisciplinary Approach.

By Akio Makishima. Elsevier, 2017, 268 pp., Paperback, $130.00. www.elsevier.com

Origins of the Earth, Moon, and Life in the Solar System: An Interdisciplinary Approach presents state-of-the-art knowledge that is based on theories, experiments, observations, calculations, and analytical data from five astrosciences: astronomy, astrobiology, astrogeology, astrophysics, and cosmochemistry. Beginning with the origin of elements, and moving on to cover the formation of the early solar system, the giant impact model of Earth and the Moon, the oldest records of life, and the possibility of life on other planets in the solar system, this interdisciplinary reference provides a complex understanding of the planets and the formation of life. Synthesizing concepts from all branches of astrosciences into one, the book is a valuable reference for researchers in astrogeology, astrophysics, cosmochemistry, astrobiology, astronomy, and other space science fields, helping users better understand the intersection of these sciences.

Eclipse: Journeys to the Dark Side of the Moon.

By Frank Close. Oxford University Press. 2017, 208 pp., Hardcover, $21.95. www.oup.com

On August 21, 2017, more than 100 million people will gather across the U.S. to witness the most-watched total solar eclipse in history. Eclipse: Journeys to the Dark Side of the Moon, by popular science author Frank Close, describes the spellbinding allure of this beautiful natural phenomenon. The book explains why eclipses happen; reveals their role in history, literature, and myth; and introduces us to eclipse chasers, who travel with ecstatic fervor to some of the most inaccessible places on the globe. The book also includes the author’s quest to solve a 3000-year-old mystery: How did the Moon move backward during a total solar eclipse, as claimed in the Book of Joshua? Eclipse is also the story of how a teacher inspired the author, at age eight, to pursue a career in science and a love affair with eclipses that has taken him to a war zone in the Western Sahara, the South Pacific, and the African bush. The tale comes full circle with another eight-year old boy — the author’s grandson — at the 2017 great American eclipse. Readers of all ages will be drawn to this inspirational chronicle of the mesmerizing experience of total solar eclipse.

Totality: The Great American Eclipses of 2017 and 2024.

By Mark Littmann and Fred Espenak. Oxford University Press, 2017, 288 pp., Hardcover, $29.95. www.oup.com

A total eclipse of the Sun is the most awesome sight in the heavens. Totality takes you to eclipses of the past, present, and future, and lets you see — and feel — why people travel to the ends of the Earth to observe them. An indispensable resource for anyone who plans to observe an eclipse, and a must read for all astronomy buffs, this new edition brims with the anecdotes, experiences, and advice of many veteran eclipse observers. It is packed with information on how to observe solar eclipses, how to photograph and videotape them, why they occur, their history and mythology, how eclipses revealed the workings of the Sun and made Einstein famous, and when and where to see future eclipses. Totality once again features the spectacular photography of Espenak, who runs the NASA Eclipse Home Page and is one of the best-known and respected of all eclipse calculators and information sources. His color photographs illuminate this unparalleled exploration of eclipses. The volume has been updated to include current information on upcoming eclipses, with new chapters on the total eclipses due in 2008, 2009, 2010, and 2017, plus all new chapters on how to photograph, video record, and process your eclipse images, with emphasis on the new generation of digital cameras. Illustrated with stunning photographs and more than a hundred maps and diagrams, here is everything you need to know about eclipses of the Sun in an accurate, clearly written, and entertaining volume that can be read by lay people and astronomers with ease and enjoyment.

WEARABLE

Eclipse Shades® Wrap-Around Goggles.

Produced by Rainbow Symphony. $19.95. www.rainbowsymphonystore.com

Are you planning to witness the solar eclipse that will be visible in the U.S. on August 21? Don’t forget your eye protection! These new plastic wrap-around goggles have the same high quality and protective optics as Rainbow Symphony’s paper Eclipse Shades®. The extra-wide temples and shield above the nose bridge eliminate most ambient light leaks, providing a truly dark viewing environment. All come with a money-back guarantee if there is ever an issue or problem with one of our products. This solar viewing product is CE-certified and meets the standard for ISO 12312-2:2015. The goggles come with a glasses lanyard and a microfiber pouch for storage and cleaning.

FOR KIDS!!!

Gravity, Orbiting Objects, and Planetary Motion.

By Lisa Hiton. Cavendish Square, 2017, 112 pp., Hardcover. $29.95. www.cavendishsq.com

Our modern understanding of the heliocentric universe developed 500 years ago. Since the time of Copernicus and Galileo, scientists have made major strides in understanding how gravity, stars, and planets interact. Gravity, Orbiting Objects, and Planetary Motion explains how early ideas have given way to sophisticated, proven theories about the universe. The book aligns with Next Generation Science Standards and also presents a look at what is next in the cutting-edge field of astronomy. For grades 8 to 12.

Planetary Exploration Series.

By various authors. Rosen Publishing, 2017, set of nine books, 32 pp. each, Hardcover, $220.05. www.rosenpublishing.com

How many planets are in our solar system? What is the environment like on these other worlds? When did people first see them? This series of nine books provide an accessible and engaging introduction to the planets in our solar system. Young readers will learn about the physical features and conditions of each planet; their orbit, spin, and position in the solar system; their moons or other satellites; and the history of human observation and exploration of each planet. There are thrilling images from some recent expeditions, and the books’ engaging design draws in readers and highlights interesting facts. This series supports the Next Generation Science Standards by helping students investigate, question, and analyze data. For grades 2 and 3.

Spaceteam: A Chaotic and Cooperative Card Game.

Produced by Timber and Bolt, $24.99. www.playspaceteam.com

Spaceteam is a fast-paced, cooperative shouting card game where you work together to repair your malfunctioning spaceship. Coordination with your team is crucial as you try to escape an impending black hole. Success is seemingly just out of reach as you encounter one complication after another. Your only hope is to work together with your Spaceteam to repair the ship before it’s too late. This game is for three to six players with expansions available for extended play. Cards are 100% plastic, water-proof, and tear-resistant. For ages 10 and up.

The Ultimate Book of Space.

By Anne-Sophie Baumann. Twirl Books, 2016, Hardcover. $19.99. www.chroniclebooks.com

With all the features that made The Ultimate Construction Site Book a bestseller, this oversized volume offers a fact-filled and action-packed look at the amazing universe of outer space. Bursting with 40 flaps, pop-ups, pull tabs, and movable parts, The Ultimate Book of Space provides a richly illustrated, hands-on exploration of space travel, Earth’s place in our galaxy, the solar system, and so much more! Sure to encourage curious young readers to venture deeper into space, this is a must-have book for any budding scientist’s library. For ages 5 to 8.

Kidz Labs Moon Torch.

Produced by 4M Industries. $6.99. Available from Amazon.com

Enjoy hours of fun with this handy 4M Kidz Labs Moon Torch Kit. Carry the beauty of moonlight and project it anywhere with this convenient Moon torch. Turn on and point the torch at walls and ceilings at night or in dark rooms to see a projection of the full Moon. Power the torch with three AG 13 button batteries (included). All the parts are made of safe, high-quality materials. For ages 5 and up.

Calendar 2017–2018

For the latest version of the meeting calendar, visit https://www.hou.usra.edu/meetings/calendar.

July

3–5 1st IUGG Symposium on Planetary Science, Berlin, Germany. http://www.dlr.de/iugg-ps2017

3–7 13th Asian-Pacific Regional IAU Meeting (APRIM 2017), Taipei, Taiwan. http://www.aprim2017.tw/

3–8 International Symposium on Education in Astronomy and Astrobiology (ISE2A), Utrecht, The Netherdlands. http://ise2a.uu.nl

10–12 Enabling Transiting Exoplanet Observations with JWST, Balitmore, Maryland. http://www.cvent.com/d/n5q7nc

10–14 Ultraviolet Sky Surveys, Tel Aviv, Israel. http://www.astro.tau.ac.il/events/uss/

14–18 LSST 2017: Project and Community Workshop, Tucson, Arizona. https://project.lsst.org/meetings/lsst2017/

16–21 XVIIIth International Conference on the Origin of Life, San Diego, California. http://www.hou.usra.edu/meetings/issol2017/

17 8th Annual Lunar and Small Bodies Graduate Conference (LunGradCon 2017), Mountain View, California. http://impact.colorado.edu/lungradcon/2017/

17–22 Formation of Complex Molecules in Space and On Planets — From Interstellar Clouds to Life, Tartu, Estonia. http://www.nordicastrobiology.net/Tartu2017

23–28 80th Annual Meeting of the Meteoritical Society, Santa Fe, New Mexico. http://metsoc2017-santafe.com/

24–28 Celebrating 25 Years of the OGLE Project, Warsaw, Poland. https://ogle25.astrouw.edu.pl/

24–28 CHEOPS Science Workshop, Schloss Seggau, Austria. http://geco.oeaw.ac.at/links_CHEOPSsw17.html

24–Aug 4 Summer School in Software Systems for Astronomy, Hilo, Hawaii. http://astro.uhh.hawaii.edu/Summer/Summer-2017/summer2017.php

25–Aug 3 Summer School “Impacts and Their Role in the Evolution of Life,” Saaremaa, Estonia. http://www.nordicastrobiology.net/Impacts2017

August

6–11 14th Annual Meeting of the Asia Oceania Geosciences Society (AOGS), Singapore. http://www.asiaoceania.org/aogs2017

8–10 The Early History of Planetary Systems and Habitable Planets, Tartu, Estonia. https://sisu.ut.ee/eac/home-0

9–11 8th Planetary Crater Consortium Meeting, Flagstaff, Arizona. http://www.planetarycraterconsortium.nau.edu/

13–16 2017 International Symposium on Planetary Remote Sensing and Mapping, Hong Kong.http://event.lsgi.polyu.edu.hk/prsm2017/

14–17 The Third Workshop on Extremely Precise Radial Velocities (EPRV III), University Park, Pennsylvania. http://exoplanets.psu.edu/

14–18 International Association of Volcanology and Chemistry of the Earth’s Interior (IAVCEI) 2017 Scientific Assembly, Portland, Oregon. http://iavcei2017.org

15–17 12th Low-Cost Planetary Missions Conference, Pasadena, California. http://lcpm12.org

15–18 Accretion: Building New Worlds, Houston, Texas. http://www.hou.usra.edu/meetings/accretion2017/

20–24 Exoclipse 2017: Exploring New Worlds in the Shade, Boise, Idaho. https://physics.boisestate.edu/exoclipse/

28–Sep 1 NBIA Summer School on Astrophysical Plasmas — From Planets to Galaxies, Copenhagen, Denmark. https://indico.nbi.ku.dk/conferenceDisplay.py?confld=933

September

5–7 Exoplanetary Systems in the PLATO Era, Coventry, United Kingdom. http://www2.warwick.ac.uk/fac/sci/physics/research/astro/research/plato_mission_conference2017/

15–17 Meteorites China — Gifts from the Universe, Kunshan, Jiangsu Province, China. http://people.duke.edu/~ng46/Meteorites-China/

17–22 European Planetary Science Congress 2017, Riga, Latvia. http://www.epsc2017.eu

18–20 4th Global Applied Microbiology Summit, Dallas, Texas. http://appliedmicrobiology.cmesociety.com/

18–22 The Many Scales of the Universe: Galaxies, Their Suns, and Their Planets, Goettingen, Germany. http://ag2017.uni-goettingen.de

19–22 The 3rd Beijing International Forum on Lunar and Deep Space Exploration, Beijing, China. http://ldse2017.csp.escience.cn

25–27 Planet Formation and Evolution 2017, Jena, Germany. http://www.astro.uni-jena.de/~pfe2017

25–29 68th Annual International Astronautical Congress, Adelaide, Australia. http://www.iafastro.org/events/iac/iac-2017/

25–29 EGU Galileo Conference “Geosciences for Understanding Habitability in the Universe,” Furnas, Azores, Portugal. http://www.egu-galileo.eu/gc2-habitability/

25–29 Geosciences for Understanding Habitability in the Universe, Furnas, Azores. http://www.egu-galileo.eu/gc2-habitability/

October

2–6 Fourth International Conference on Early Mars: Geologic, Hydrologic, and Climatic Evolution and the Implications for Life, Flagstaff, Arizona. https://www.hou.usra.edu/meetings/earlymars2017/

9–13 The Eighth Moscow Solar System Symposium, Moscow, Russia. http://ms2017.cosmos.ru

10–12 Annual Meeting of the Lunar Exploration Analysis Group, Columbia, Maryland. https://www.hou.usra.edu/meetings/leag2017/

12–13 Back to the Moon Workshop, Houston, Texas. https://www.hou.usra.edu/meetings/moon2017/

15–20 49th Annual DPS Meeting, Provo, Utah. https://dps.aas.org/

16–20 Fifth Workshop on Robotic Autonomous Observatories, Mazagon, Spain. http://astrorob.iaa.es

17–20 The Cosmic Wheel and the Legacy of the AKARI Archive: From Galaxies and Stars to Planets and Life, Tokyo, Japan. http://www.ir.isas.jaxa.jp/AKARI/akari2017/

22–25 2017 GSA Annual Meeting, Seattle, Washington. https://www.geosociety.org/GSA/Events/Annual_Meeting/GSA/Events/gsa2017.aspx

November

6–11 9th International Conference on Geomorphology, New Delhi, India. http://www.icg2017.com/

7–9 SPICE Training Class, Pasadena, California.https://naif.jpl.nasa.gov/

11–12 Workshop on Modern Analytical Methods Applied to Earth, Planetary, and Material Sciences II, Budapest, Hungary. https://www.hou.usra.edu/meetings/methods2017/

13–15 1st IAA Conference on Space Situational Awareness, Orlando, Florida. http://www.icssa2017.com

13–17 Habitable Worlds 2017: A System Science Workshop, Laramie, Wyoming. https://nexss.info/community/workshops/habitable-worlds-2017

26–Dec 1 IAU Astrobiology 2017 Conference, Coyhaique, Chile. http://astrobiology2017.org/

December

4–8 51st Eslab Symposium “Extreme Habitable Worlds,” Noordwijk, The Netherlands. http://esaconferencebureau.com/2017-events/eslab2017

11–15 2017 AGU Fall Meeting, New Orleans, Louisiana. http://fallmeeting.agu.org

18–20 Next-Generation Suborbital Researchers Conference, Broomfield, Colorado. http://nsrc.swri.org

February 2018

6–9 Magnetic Fields or Turbulence: Which is the Critical Factor for the Formation of Stars and Planetary Disks?, Hsinchu, Taiwan. http://events.asiaa.sinica.edu.tw/workshop/20180206/index.php

25–Mar 2 The 2nd Rencontres du Vietnam on Exoplanetary Science, Quy Nhon, Vietnam. http://rencontresduvietnam.org/conferences/2018/exoplanetary_science/

March

19–23 49th Lunar and Planetary Science Conference, The Woodlands, Texas. https://www.hou.usra.edu/meetings/lpsc2018/

April

24–26 Planetary Science Informatics and Data Analytics Conference, St. Louis, Missouri. https://psida.rsl.wustl.edu/

May

1–3 Mercury: Current and Future Science of the Innermost Planet, Columbia, Maryland. https://www.hou.usra.edu/meetings/mercury2018/

7–11 Differentiation: Building the Internal Architecture of Planets, San Gabriel Valley, California. https://www.hou.usra.edu/meetings/differentiation2018/

14–Jun 8 MIAPP 2018 Workshop — Near Earth Objects: Properties, Detection, Resources, Impacts and Defending Earth, Munich, Germany. http://www.munich-iapp.de/programmes-topical-workshops/2018/near-earth-objects-properties-detection-resources-impacts-and-defending-earth/

Table of Contents

Table of Contents

Feature Story

From the Desk of Jim Green

News from Space

Meeting HIghlights

Spotlight on Education

In Memoriam

Milestones

New and Noteworthy

Calendar 2017–2018