LPI Seminar Series
2022
The LPI Seminar Series brings prominent scientists to the LPI to present on a broad array of scientific disciplines that advance our understanding of the solar system. The seminar series, which began in September 1969, has brought many notable contributors from numerous research and academic institutions to the LPI. Seminars are typically held on Thursdays from 3:00-4:00 p.m. US/Central, but dates and times are subject to change. All seminars will be held virtually until further notice.
Sign up for LPI Seminars to receive email notifications of upcoming seminars and details on how to join the virtual seminar. For more information, please contact Patrick McGovern ([email protected]) and Sam Crossley ([email protected]).
See also the Rice University Department of Physics and Astronomy Colloquia and the Department of Earth Science Colloquia pages for other space science talks in the Houston area.
View RecordingsFebruary 2022
Thursday, February 10, 2022 - Virtual, 3:00 PM
Jessica Noviello, NASA Postdoctoral Management Program Fellow
LPI Seminar: The Internal Happenings of Dwarf Planet Haumea
Since its discovery almost two decades ago, 2003 EL61 Haumea has puzzled the observing and planetary science communities. Haumea is a dwarf planet that orbits the Sun at 43 AU in the Kuiper Belt. Observations from ground-based telescopes revealed Haumea’s size and shape to be a large (average radius ~800 km) triaxial ellipsoid shape with an abnormally high rotational period of just 3.91 hours, making it the fastest spinning large body in the solar system. Later observations also revealed Haumea to have two moons and even a ring system. Its high albedo and spectral signatures suggest that its surface is covered by water ice. Unfortunately, this is almost everything known for certain about Haumea. I will talk about the geophysical and geochemical modeling I have done to help answer some outstanding questions, including making educated guesses about the size and composition of Haumea’s core, and I will connect the ideas to exoplanet research. I will also briefly speak to the management activities I have done as part of the leadership team for the NExSS research coordination network in support of NASA’s astrobiology goals. Watch Video https://youtu.be/BuAx7AhUUY8
Thursday, February 17, 2022 - Virtual, 1:00 PM
Renee C. Weber, NASA’s Marshall Space Flight Center
LPI Seminar: The Lunar Geophysical Network Mission
The Moon represents an end-member in the differentiation of rocky planetary bodies. Its small size (and, therefore, heat budget) means that the early stages of differentiation have been frozen in time. But despite the success of the Apollo Lunar Surface Experiment Package (ALSEP), significant unresolved questions remain regarding the nature of the lunar interior. General models of the processes that contributed to the formation of the present-day lunar interior are currently being challenged. While reinterpretation of the Apollo seismic data has led to the identification of a lunar core, it has also produced a thinning of the nearside lunar crust from 60-65 km in 1974, to 45 km in 2002, to 30-38 km today. With regard to the deep interior, Apollo seismic data have been used to infer the presence of garnet below ~500 km, but the same data have also been used to identify Mg-rich olivine instead. A global lunar geophysical network (seismometer, heat flow probe, magnetometer, laser retro-reflector) is essential to defining the nature of the lunar interior and exploring the early stages of terrestrial planet evolution. Such a network would also add tremendous value to the GRAIL and SELENE gravity data. Identification of lateral and vertical heterogeneities, if present within the Moon, will yield important information about the early presence of a global lunar magma ocean (LMO) as well as investigating the stratification in the mantle from LMO cumulate overturn. LGN would also provide new constraints on lunar seismicity, including shallow moonquakes that have been linked to young thrust fault scarps, suggesting current tectonic activity. Advancing our understanding of the Moon’s interior is critical for addressing these and many other important lunar and Solar System science and exploration questions. Watch Video: https://youtu.be/oKA2yCDV5ZI
Thursday, February 24, 2022 - Virtual, 1:00 PM
Sandrine Péron, Institute of Geochemistry and Petrology
LPI Seminar: Delivery Of Volatiles To Terrestrial Planets: A Perspective From Heavy Noble Gases
Delivery of volatiles (e.g., carbon, nitrogen, water) to terrestrial planets was a major process that shaped their early surface environments. Models of volatile accretion often start with acquisition of gases derived from the solar nebula, followed by delivery of chondritic volatiles during the main and/or towards the end stages of planetary formation. However, the timing of accretion and the sources of volatiles remain controversial. Determining the noble gas compositions of planetary mantles provides direct observational clues for planetary formation models on both the sources and timing of accretion of volatiles. Noble gases are invaluable tracers of volatile sources due to their inertness. However, the heavy noble gas (krypton and xenon) compositions of Earth and martian mantles remain poorly determined, in part due to analytical challenges. In particular, the six stable isotopes of krypton are ideally suited to deconvolve chondritic from solar sources, because chondritic and solar krypton are, respectively, enriched and depleted in heavy krypton isotopes compared to atmospheric krypton. Sandrine Péron of the ETH Zürich will discuss results of heavy noble gas analyses, in particular krypton, of oceanic island basalts from the Galápagos and Iceland hotspots, sampling Earth’s deep mantle, and of the meteorite Chassigny, sampling the martian mantle. Registration is required: https://bit.ly/3gWxdKQ
March 2022
Thursday, March 24, 2022 - Virtual, 3:00 PM
Rita Parai , Washington University, St Louis
LPI Seminar: Accretion of a dry ancient plume mantle from noble gas isotopes
Primordial volatiles were delivered to terrestrial reservoirs during Earth’s accretion, and the plume mantle source is thought to have retained a greater proportion of primordial volatiles compared to the upper mantle. Here I demonstrate that mantle helium (He), neon (Ne) and xenon (Xe) isotopes require that the plume mantle had low concentrations of volatiles like Xe and H2O at the end of accretion compared to the upper mantle. A lower extent of mantle processing alone is not sufficient to explain plume noble gas signatures. Primordial isotope ratios are used to determine proportions of solar, chondritic, and regassed atmospheric volatiles in the plume mantle and upper mantle. Pairing primordial isotopes with radiogenic systems gives an absolute concentration of Xe in the plume source at the end of accretion that is ~4x less than that determined for the ancient upper mantle. A record of limited accretion of volatile-rich solids thus survives in the He-Ne-Xe signatures of mantle rocks today. A primordial viscosity contrast originating from a factor of ~4 to 80x lower H2O concentration in the plume mantle compared to the upper mantle may explain (a) why giant impacts that triggered whole mantle magma oceans did not homogenize the growing planet, (b) why the plume mantle has experienced less processing by partial melting over Earth history, and © how early-formed isotopic heterogeneities may have survived ~4.5 Gyr of solid-state mantle convection. Registration is required: https://bit.ly/3CT7ixC
Thursday, March 31, 2022 - Virtual, 3:00 PM
Nancy Chabot , Johns Hopkins Applied Physics Laboratory
LPI Seminar: The Double Asteroid Redirection Test (DART) Mission
NASA’s Double Asteroid Redirection Test, or DART, is the world’s first full-scale planetary defense test, demonstrating one method of asteroid deflection technology. DART’s target is the binary asteroid system Didymos. Although not on a path to collide with Earth and no actual threat to our planet, the Didymos system is an ideal candidate for humankind’s first planetary defense experiment. It’s composed of two asteroids: a larger asteroid named Didymos and a smaller asteroid moonlet named Dimorphos , which orbits Didymos. By crashing into Dimorphos and changing its orbit around Didymos slightly, DART will prove the technological capability to autonomously navigate to a target asteroid and to intentionally collide with it, providing information to further improve humanity’s understanding of how to potentially protect Earth from asteroid impacts in the future. DART launched in November 2021 and is on its way to collide with Dimorphos on 26 September 2022. DART was developed and is managed by Johns Hopkins Applied Physics Laboratory for NASA's Planetary Defense Coordination Office. For more information, visit: https://dart.jhuapl.edu/ Registration is required: https://bit.ly/3JFPp8c
April 2022
Thursday, April 7, 2022 - Virtual, 3:00 PM
André Izidoro, Rice University
LPI Seminar: The Solar System in the Context of Exoplanets
More than 5000 exoplanets have been discovered so far. One of the most intriguing outcomes of our planetary census is that the solar system seems to be dramatically uncommon. Statistical analyses suggest that less than 1% of the sun-like stars host Jupiter-analogues. This fraction drops to less than 0.1% when one accounts for all star-types. "Hot super-Earths" or "hot mini-Neptunes" — planets with sizes between those of Earth and Neptune, and orbital period shorter than ~100 days — orbit at least 30%-50% of the sun-like stars in our galaxy. Yet, no hot super-Earth exists in the solar system. Exoplanets come in a diversity of system architectures, largely different from those seen in the solar system. These findings have challenged and reinvigorated our view of how our own solar system formed and evolved. Dr. Izidoro will discuss critical events that may have shaped the formation of our planetary system. He will use meteorite data, asteroid observations, observations of disks around young stars to build a planet formation model that accounts for the solar system planetary architecture. He will use this model to explain why Mars is relatively much smaller than Earth, the origin of Earth's water, the origin of the compositional dichotomy of the asteroid belt, and why Earth is not a super-Earth. Registration is required: https://bit.ly/36UBU6n
Thursday, April 14, 2022 - Virtual, 3:00 PM
Cauê Borlina, Johns Hopkins University
LPI Seminar: Understanding the Evolution of the Early Solar System through Paleomagnetism of Meteorites
Magnetic records from meteorites and their components can provide important information about the evolution and architecture of the early solar system. That is because large-scale magnetic fields and gas are coupled in protoplanetary disks. In this talk, we explore how we can use micro-paleomagnetism to obtain magnetic records from 100 µm-sized meteoritic inclusions (i.e., calcium-aluminum-rich inclusions and chondrules) to obtain constraints on the evolution of the early solar system. Dr. Borlina will discuss how (1) the magnetic records from calcium-aluminum-rich inclusions point to the presence of magnetized disk winds and/or stellar outbursts during the very beginning of the solar system and (2) the magnetic records from chondrules suggest the presence of a disk substructure a few million years later. These results provide information about mechanisms that drove mass and angular momentum during the protoplanetary disk phase of the solar system, and how chemical reservoirs were kept apart during that time. Learning how our solar system evolved can help us understand how planetary systems form elsewhere. Watch Video: https://youtu.be/iHfHYypkUYk
Thursday, April 21, 2022 - Virtual, 3:00 PM
Michael K. Shepard, Bloomsburg University of Pennsylvania
LPI Seminar:A Survey of the M-Class Asteroids: Results from the Past Decade
The M-class asteroids are a small but intriguing subset of the Main Asteroid Belt population. Are they the denuded iron core remnants of the early planetesimals? Shattered and reassembled silicate/iron mixtures? Examples of iron volcanism? Are they even a single type of object? Or are they two or more unrelated types that just happen to look similar? One has been visited by spacecraft (21 Lutetia) and another will be shortly (16 Psyche). We will look at what we know and what has been recently learned about these objects in an attempt to address some of these questions. Watch Video: https://youtu.be/BuAx7AhUUY8
Thursday, April 28, 2022 - Virtual, 3:00 PM
Anat Shahar, Carnegie Science, Department of Terrestrial Magnetism
LPI Seminar: An Experimental Geochemistry View on Planetary Evolution
One of the broader goals in Earth and planetary science is to understand the evolution of a planet from accretion to its present state. While each planet has a unique path, there are ubiquitous processes such as core formation, evaporation, and magmatic differentiation that can be studied in order to better understand planetary formation and evolution in general. In our current research we combine methods from stable isotope geochemistry and experimental petrology in order to enhance our understanding of these planetary scale processes. Experiments at high pressure and temperature simulate natural conditions within the Earth or planetary bodies, while stable isotopes can be used to show which physical and chemical processes natural materials have undergone. Each process that has occurred throughout the planet’s history has resulted in an isotopic fractionation of an element; the key is to understand the signal. This multi-disciplinary approach has been shown to be an effective way to study processes occurring at all conditions from the high-pressure metallic core of a planet to the low-temperature surface. In this talk I will synthesize what we have learned from experiments as well as compare our experimental results to terrestrial and extra-terrestrial samples. We find that stable isotopes are powerful tracers of planetary processes even at high temperature and pressure, and that experiments are the most effective way of unlocking the secrets within these tracers. Registration is required: https://bit.ly/3k8doS7
May 2022
Thursday, May 12, 2022 - Virtual, 3:00 PM
Max Collinet , German Aerospace Center
LPI Seminar: The Diversity of Igneous Processes in Planetesimals and Implications for the Distribution of Alkali Elements in the Early Solar System
Achondrite meteorites are highly variable in composition: some are ultramafic (primitive achondrites), basaltic (e.g., eucrites and angrites), or (trachy-) andesitic (e.g., GRA 06128, NWA 11119 and Erg Chech 002). These different groups correspond to the mantle and crust of planetary building blocks, respectively. They represent a unique opportunity to constrain the early melting processes that affected planetesimals and could have influenced the final composition of planets. Registration is required: https://bit.ly/3N4gLWy
Thursday, May 19, 2022 - Virtual, 4:00 PM
Motoo Ito, Japan Agency for Marine-Earth Science and Technology
LPI Seminar: Hayabusa2 Returned Samples: Unique and Pristine Record of Solar System Materials from Asteroid Ryugu
On 6th December 2020, ~5.4 g of material was delivered to Earth from the C-type asteroid Ryugu by the Hayabusa2 spacecraft. Here, we summarize the first-year results of an integrated bulk and micro-analyses of Ryugu particles by the Phase2 curation Kochi to elucidate the nature, origin and history of asteroid Ryugu, and to investigate the similarities to known extraterrestrial samples. Ryugu particles provide a unique insight into the relationship between aliphatic-rich organics and the surrounding hydrous minerals at sub-micrometer scale during water-rock interactions. This dataset provides a better understanding of the origin and early evolution of Solar System organic matter and demonstrates that Ryugu particles are among the most uncontaminated extraterrestrial materials so far studied to date. Watch Video: https://www.youtube.com/watch?v=W6eHof6wZns
June 2022
Thursday, June 30, 2022 - Virtual, 3:00 PM
Katherine Bermingham, Rutgers University
LPI Seminar: Constraining the genetics of Earth’s late-stage accretion
Earth formed from the sequential addition of Solar System-derived bodies sourced from different heliocentric distances. Understanding the origin of Earth, therefore, requires knowledge of from where in the Solar System and when Earth’s building blocks accreted. The silicate Earth, however, has been mixed for over 4.5 billion years via geodynamical processes. Undoubtedly, these processes led to the attenuation of any original discrete chemical fingerprints inherited from Earth’s building blocks. Determining Earth’s building blocks and their relative timing of accretion, however, is possible if the compositions (i.e., genetics) of remnant planetary building blocks are contrasted with mantle-derived geochemical data that track different stages of Earth accretion history. An approach is to progressively go back in time through a study of siderophile (iron-loving) elements Mo and Ru to identify the genetic signatures of dominant building blocks during Earth’s final stages of accretion (i.e., during and following core formation). The modern Bulk Silicate Earth (BSE) Mo and Ru isotopic estimates provide cumulative yet complementary genetic information about Earth’s building blocks. Constraining, to high precision, the Mo and Ru BSE estimate is required to identify the dominant genetic signature of material accreted. Furthermore, discovery of anomalous Mo and/or Ru isotopic compositions of mantle domains would pinpoint the genetic components of late-stage building blocks. Katherine Bermingham (Rutgers University) will discuss results of high precision Mo and Ru isotope analyses of terrestrial materials and how these data place constraints on the genetics of Earth’s late-stage building blocks. Registration is required:
July 2022
Thursday, July 7, 2022 - Virtual, 1:00 PM
James Dottin, Carnegie Science
LPI Seminar: Isotopic constraints on the lunar sulfur cycle
The origin, evolution, and cycling of volatiles on the moon are established by processes such as the giant moon forming impact, lunar magma ocean degassing, mantle crystallization and degassing, and lunar surface gardening events. These processes are typically controlled by mass dependent fractionation processes and, as such, have been readily documented in a variety of stable isotope systems (such as K, Cl, Zn, S, ect.). However, a role for mass-independent processes, such as atmospheric photochemistry, has yet to be demonstrated. For this seminar, I will present the first high precision quadruple sulfur isotope measurements on lunar soils and glasses collected during Apollo 17. We observe mass-independent fractionation of sulfur in lunar regolith from at least one site and not in regolith from other sites. This signature is attributed to photochemistry in sunlit regions and the absence of such a signature is ascribed to gardening in shadowed areas. The compositional dichotomy may also be related to volatile availability from solar wind implantation. Orange glass also preserves mass-independent sulfur. The source of the anomalous sulfur from the lunar mantle is unclear, but likely represent S photochemically processed early in the Moon's history that was then delivered to the mantle during the mantle overturn event. Registration is required: https://bit.ly/3OEu80T
Thursday, July 14, 2022 - Virtual, 3:00 PM
Brian Day, Ames Research Center
LPI Seminar: Lunar and Planetary Data Visualization and Analysis Using NASA’s Solar System Treks Portals
NASA's Solar System Treks (https://trek.nasa.gov) online portals for lunar and planetary mapping and modeling provide web-based suites of interactive visualization and analysis tools to enable mission planners, planetary scientists, students, and the general public to access mapped data products from many different instruments aboard past and current missions for a growing number of planetary bodies. Several new portals and exciting new analysis tools have recently been introduced to the suite. This presentation will provide an overview of the portals and their capabilities, and highlight new features. Registration is required: https://bit.ly/3uDYWqT
August 2022
Thursday, August 4, 2022 - Virtual, 3:00 PM
Sarah Valencia, NASA Goddard Spaceflight Center
LPI Seminar: The formation of lunar granite: Observations from Remote Sensing and Apollo Samples
Granite is one of the most rare and enigmatic rock types in the lunar sample collection, yet is known to form large constructs on the Moon. Without the help of plate tectonics and water, it is unclear how these large-scale silicic bodies form. In this talk I will present the current state of knowledge of silicic volcanism on the Moon through remote sensing and by an examination of the largest granite-bearing rock returned from the Apollo Program, sample 12013. Registration is required: https://bit.ly/3JjtMuZ
September 2022
Thursday, September 29, 2022 - Virtual, 3:00 PM
Laurent Montesi, University of Maryland College Park
LPI Seminar: Lava Tube Evolution and Exploration
Future explorers of the Moon and Mars may take advantage of lava tubes and other underground voids as long-term shelters and resource providers. However, the location of these features underground means they cannot be directly observed. Even detecting where a lava tube may be located is not a trivial matter. A combination of geophysical investigations, analogy studies, and theoretical modeling is, therefore, necessary to predict what lava tubes on other planets may be like. Models of lava tube evolution developed under the auspices of the GEODES virtual institute will be presented. The presentation will focus on the development of two geomorphological features predicted by these models: a sinuous ridge that follows the trace of the tube at the surface and cracks that may develop on either side of the tube. These features can provide information on the size and shape of a tube before in-situ exploration. Preliminary evidence will be shown that these morphological features exist at locations where other data indicate a lava tube may be present. Registration is required: https://bit.ly/3yaDMm3
October 2022
Thursday, October 13, 2022 - Virtual, 3:00 PM
Megan Newcombe, University of Maryland
LPI Seminar: Efficient degassing of early-formed planetesimals and the ureilite parent body: Water delivery to Earth via unmelted material
The timing of delivery and the types of bodies that contributed volatiles to the terrestrial planets remains highly debated. For example, it is unknown if differentiated bodies, such as that responsible for the Moon-forming giant impact, could have delivered substantial volatiles, or if smaller, undifferentiated objects were more likely vehicles of water delivery. Measurements of water contents of nominally anhydrous minerals and melt inclusions in ungrouped achondrite meteorites (mantles/crusts of differentiated planetesimals) from both the inner and outer portions of the early Solar System are extremely low. Furthermore, measurements of water in minerals and quenched melts in ureilites demonstrate efficient degassing of water from the ureilite parent body (UPB), even though the UPB did not have a global magma ocean. Our results demonstrate that partially melted planetesimals efficiently degassed prior to or during melting. This finding implies that water could only have been delivered to Earth via unmelted material. Watch video here: https://www.youtube.com/watch?v=PPUfXSfwaKM
Thursday, October 20, 2022 - Virtual, 3:00 PM
Zoltan Vaci, Washington University in St. Louis
LPI Seminar: Symplectite formation in ultramafic planetary materials
Symplectites are vermicular intergrowths of two or more phases that are found in a large variety of igneous and metamorphic rocks on Earth and extraterrestrially. The formation of spinel-pyroxene symplectites in mafic to ultramafic planetary samples remains enigmatic after decades of research into samples from the Moon, Mars, Vesta, and planetesimals. The ultramafic suite that includes several dunitic and lherzolitic achondrites, as well as harzburgite clasts found in Howardites, contains clues to the formations of these features and suggests interaction with an exotic melt component. We conducted sample analysis and performed petrologic experiments to examine the petrogenesis of these features. Registration is required: https://bit.ly/3ezge3w
Thursday, October 27, 2022 - Virtual, 3:00 PM
Chi Ma, California Institute of Technology
LPI Seminar: Nanomineralogy of Meteorites: Discovery of New Minerals Representing Extreme Conditions of Formation
During our ongoing nanomineralogy investigation of meteorites since 2007, 45 new minerals have been discovered. 19 are from the Allende meteorite, including 12 refractory minerals like allendeite Sc₄Zr₃O₁₂, tistarite Ti₂O₃ and panguite (Ti⁴⁺,Al,Sc,Mg,Zr,Ca,□)₂O₃, which are among the first solids formed in the solar system. To date, 50+ refractory minerals and 20+ presolar minerals mark the very beginning of the solar mineral evolution at 4.567 billion years ago. Ten new high-pressure minerals have been discovered in shocked meteorites, including bridgmanite (MgSiO₃-perovskite, the most abundant mineral in Earth), ahrensite (Fe₂SiO₄-spinel) and tissintite ((Ca,Na,□)AlSi₂O₆-clinopyroxene). Each new mineral reveals distinctive forming environments, providing insights into nebula, parent-body processes, or shock conditions. Presented here are some of discovery stories, demonstrating how nanomineralogy works and plays a unique role in Earth and planetary science research. Registration is required: https://bit.ly/3gFVNTm
November 2022
Thursday, November 3, 2022 - Virtual, 3:00 PM
Soumya Ray, University of Maryland, College Park
LPI Seminar: Mass spectrometers in the laboratory and beyond: what do they tell us about our Solar System?
Mass spectrometers have provided invaluable insights into the chemical makeup of various planetary materials. In this talk, I will discuss the iron isotopic compositions of aubrites and what they tell us about the differentiation processes that occurred on their parent body(s). I will also talk about miniaturized, spaceflight mass spectrometers capable of analyzing inorganic composition and organic compounds at ultrahigh mass resolving power. Registration is required: https://bit.ly/3zST53F
Thursday, November 10, 2022 - Virtual, 3:00 PM
Sierra Ferguson, Southwest Research Institute
LPI Seminar: Smashing Saturn: Insights from Impact Crater Analysis on Saturn’s Satellites
An outstanding question after the conclusion of the Cassini mission is “How old are the inner satellites and how did they form?” This question is of critical importance for the refinement of how solar systems and giant planet systems form and evolve. Determining the ages of the satellites also has broad scale implications for active geologic processes and the durations of subsurface oceans that may have once been present under the ice shells of these mid-sized moons. One of the most direct ways to test the ages of a planet's surface is through the use of impact craters and analysis of their sources. This research utilizes images from the Cassini Imaging Science Subsystem (ISS) to analyze craters on three of the mid-sized moons of Saturn; Mimas, Tethys and Dione. Additionally, we use elliptical craters to further test the surface ages since elliptical craters provide another means of assessing the bombardment environment around Saturn as they record the primary direction of the object that created the crater upon impact on the surface. We have mapped these craters on Mimas, Tethys, and Dione to analyze the global distributions of these craters and their orientations. Across Tethys and Dione, we find that in the equatorial regions between 30° N/S in latitude, the orientations of the elliptical craters are predominantly oriented East/West. Whereas this signal isn’t observed within the cratering record of Mimas. This potentially suggests that the source of material that was available to create these craters didn’t extend closer in to Saturn, or that this material could have been present at Mimas, but with a diminished signal than on the outer moons. An interpretation of this E/W signal is that these craters were formed by a local planetocentric source as it would likely lie within the same orbital plane as the satellites. In addition to the elliptical craters, we mapped at a regional scale (~200 m/pix) across all three surfaces to investigate potential regional differences in the cratering and what that can reveal about the impactor sources for these craters. Neither of the previously predicted production functions for the outer planets fit perfectly with the observations we have in the Saturn system. We further interpret this difference to be indicative of a local planetocentric source that has had a large impact on the observed crater record. Registration is required: https://www.zoomgov.com/meeting/register/vJItc-qrpzIiHgHXhO-9qyj9jgGf5NcwRgo
Thursday, November 17, 2022 - Virtual, 3:00 PM
Susanne P. Schwenzer, The Open University
LPI Seminar: Assessing Reaction Pathways on Mars — From Meteorites to Sample Return
Orbiters, rovers, and landers have returned a plethora of information from Mars. While exploration on Mars continues, the question of habitability also becomes more specific. From the broader aim of "follow the water," investigations have moved to very specific environments and to the fine details of the environmental conditions within them. Of specific interest are environments with alteration minerals. While much information can be gained from observations, one critical factor is not observable: the reaction pathway and its corresponding fluid. This talk demonstrates how thermochemical modeling can fill this gap and what we can learn from theoretical investigations of the observed environments. Registration is required: https://www.zoomgov.com/meeting/register/vJItc-qrpzIiHgHXhO-9qyj9jgGf5NcwRgo
December 2022
Thursday, December 1, 2022 - Virtual, 3:00 PM
Oliver White, SETI Institute
LPI Seminar: A Global Geologic Map of Pluto
The flyby of Pluto in 2015 by NASA’s New Horizons spacecraft returned high-quality images that revealed a diverse range of terrains with disparate morphologies and crater spatial densities, implying a complex geological history. This presentation focuses on the first draft of a global geologic map of Pluto for the >75% of Pluto’s surface that was imaged by New Horizons, to be published by the USGS. The wide range of surface ages across Pluto appears to be primarily a consequence of how surface volatile distribution is affected by atmospheric, geographic, and topographic effects. Large-scale geologic activity is ongoing in the form of convection and glacial flow in Sputnik Planitia, Pluto's prime repository of surface nitrogen ice that is contained within a deep impact basin. There is a gradual transition from volatile ice-poor, cratered, and ancient terrains west of Sputnik Planitia, to younger accumulations of large deposits of volatile ices to its east, interpreted to stem from Sputnik Planitia's regulation of atmospheric circulation and, consequentially, the longitudinal distribution of volatiles. Volatile accumulation east of Sputnik Planitia is also thicker and younger in the equatorial regions than in the north, reflecting an additional control on volatile distribution by Pluto's distinct climate zones that stem from its high obliquity. Pluto's most ancient terrains are represented by smooth plains, thin, eroded mantling deposits, and glacially carved landscapes, and include the complex ridge-trough tectonic system that follows a great circle. The configuration of these ancient landscapes may indicate that the ridge-trough system was aligned along Pluto's equator prior to true polar wander that occurred in response to the Sputnik basin impact. Relatively recent, large-scale cryovolcanism may be represented by the enigmatic Wright and Piccard Montes to the south of Sputnik Planitia. Registration is required: https://www.zoomgov.com/meeting/register/vJItc-qrpzIiHgHXhO-9qyj9jgGf5NcwRgo
