Effective January 1, 2011, LPI seminars will be held on Fridays.
LPI seminars are held from 3:30–4:30 p.m. in the Lecture Hall at USRA, 3600 Bay Area Boulevard, Houston, Texas. Refreshments are served at 4:30 p.m. For more information, please contact Georgiana Kramer (phone: 281-486-2141; e-mail: email@example.com) or Patricia Craig (phone: 281-486-2144; e-mail: firstname.lastname@example.org). A map of the Clear Lake area is available here. This schedule is subject to revision.
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Mars Pathfinder provided the highest spatial and spectral resolution and the first in situ chemical analyses of Martian rocks. These data reveal two important insights: 1) Rocks at the Pathfinder site have been significantly abraded by windborne sand. This likely occurred in the late Hesperian-early Amazonian, when higher particle supplies contributed to greater aeolian scour than is possible today. 2) Mars rocks are pervasively covered with airfall dust. The dust influences both the visible/near IR signature and surficial chemical composition. Together, these two observations support a model whereby the surfaces of Martian rocks have been altered physically and chemically. The true, pristine, nature of rocks on Mars lies beneath this altered veneer.
Contrary to what many believe, NASA has no long-term goal or plan and no process by which such a plan might be developed. The agency has largely been in a "holding pattern" since the lunar landings over 30 years ago, with an Apollo-style management and operational idiom and a NACA-level budget. Although much of the current PR focuses on missions to Mars as the next big program, I suggest instead that the goal of a lunar outpost more readily fits economic, political, and technical realities. Such a program would both create the infrastructure that would allow us to go on to the planets and accomplish significant and recognizable near-term milestones.
Manifested for flight on the next Lander to Mars, the MIP Flight Demonstration will be the first hardware to utilize the indigenous resources of a planet or moon. The objectives of MIP are to characterize the performance of processes and hardware that are important to In-situ-propellant-production (ISPP) concepts and to demonstrate how these processes and hardware interact with the Mars environment. MIP's successful operation will enable future robotic and human missions to rely on propellants produced from Martian resources.
The prolonged volcanic history of the Tharsis region of Mars indicates that upwelling mantle convection has been important in this region for most of the history of Mars. I have performed a series of mantle convection simulations that include calculations of mantle melting and magma production. I will compare the model predictions with constraints derived from geologic mapping and from studies of the SNC meteorites. I will also explore the implications of these results for the thermal history of Mars.
Fundamental questions surrounding the possibility of a universal biology can not be answered without samples from other planets. In lieu of those samples much can be learned from earth's earliest biosphere. Intracratonic basins contain the best record of these early events and the Australian craton is richly endowed in early intracratonic settings. There is a growing body of evidence to suggest that there is a periodic cycle of supercontinent coalescence and dispersal. Our work suggests that these basins are linked to the supercontinent cycle and that in a general way the evolution of life is driven by these large-scale planetary processes. These conclusions are pessimistic but have major implications for any strategy to be established in the search for extraterrestrial life.
Preservation potential for bacterial bodies is poor, however, bacteria have the ability to induce the precipitation of a host of minerals (e.g., carbonates, Fe-, Mn-, and K-rich precipitates); these precipitates can be recognized in the rock record. In the lab, extracellular mineral precipitates occur as individual crystals, crystal bundles (rods, spheres, dumbbells, disks, rhombohedra, tetragonal dipyramids, etc.), and as solid crusts. In the terrestrial record, the best documented bacterially induced precipitates take the form of silt- to fine sand-sized round to elliptical mineral aggregates around clumps of bacteria (e.g., peloids in coral reefs) and shrubs or bushes (hot water travertines).
The martian soil is an integrated record of weathering processes and climate on Mars. By combining laboratory experiments with spacecraft observations, we hope to identify the components of the soil to understand what information they preserve about the processes that have modified the Martian surface. In particular, water and sulfates appear to play an important role on Mars. I will describe our efforts to understand the nature of sulfates in martian soil, especially the cemented soils known as duricrusts.
The heartbreaking losses of four Mars-bound spacecraft in 1998 has led to some profound introspection at NASA, and also recriminations both over how the programs were managed, and how the management failures were reported to the public. From the perspective of a lifelong "rocket scientist" AND writer for the public, Jim Oberg did his own digging into the loss of Mars Climate Orbiter (see his December 1999 article in SPECTRUM, reproduced on his home page www.jamesoberg.com), the Mars Polar Lander failure, and into the cultural weaknesses which many experts within and without NASA had been warning about for years. Oberg will give credit to the thoroughness and integrity of the accident review boards but will argue that NASA leadership still doesn't seem to "get it" about where the flaws originated. For example, the assertion that "maybe management pushed too hard" misses the point, since it's the job of good leaders to push hard -- the flaw, in Oberg's view, is that NASA management created a bureaucracy unwilling or incapable of "pushing back" (based on experience, intuition, and professional integrity) when the directives from the top got too unrealistic. This culture remains unacknowledged and uncorrected and may lead to more unpleasant and expensive setbacks. After 22 years at JSC, Oberg has been a full-time free-lance consultant and writer for the last three years. His most recent book, "Space Power Theory", assessed the motivations a nation uses to design a productive space program. He was featured on the recent NOVA program on ISS, "Stationed in the Stars".
The Mars Global Surveyor (MGS) spacecraft was launched from Cape Kennedy in November 1996. MGS was put into orbit around Mars in September of 1997 and has since been sending back data from a suite of instruments, including the Thermal Emission Spectrometer (TES). The TES instrument is an interferometric spectrometer designed to map the surface mineralogy of Mars by measuring the midinfrared emitted radiation over the spectral region of ~1600 to 200 cm-1 (~ 6 to 50 ╡m). This mineralogically sensitive technique utilizes the characteristic intra- and inter-molecular vibrations of minerals that are manifested in the midinfrared spectra. These spectral "fingerprints" are unique because they are dependent upon chemical composition, crystal structure, crystal orientation, and other factors.
Midinfrared spectral data received from the MGS-TES instrument have indicated the presence of a large deposit of hematite (alpha-Fe2O3) in Sinus Meridiani, Mars. This hematite deposit, that is accompanied by basalt, is areally extensive, encompassing and area ~350 by 500 km.
To better understand the geologic context of this large mineral occurrence, a detailed laboratory spectroscopic investigation was conducted using more than 20 terrestrial hematite samples so that their spectra could be compared to the martian spectra. The samples included red and gray polycrystalline hand samples, gray single-crystal hand samples, and red and gray fine- and coarse-grained particulates. The laboratory analyses provided thermal emissivity spectra that, when compared to the hematite emissivity spectra from Mars, suggest the Sinus Meridiani hematite is possibly an exposure of oriented hematite grains. These grains are likely coarser than 10 ╡m (and may be much larger) and gray in color. The characteristic of oriented grains is suggested by the apparent crystal axis-dependence of the energy emitted from the surface of Mars. The strong degree of crystal alignment exhibited in the emissivity spectra of Mars suggests that these oriented hematite crystals most likely occur as outcrops comprised of aligned specular hematite grains (possibly schistose in texture), or possibly as well-aligned platy particles. We are investigating the nature of this vast hematite deposit in order to understand better the geologic setting and infer past conditions and geological evolution on Mars.
Any credible scenario for Mars exploration will involve human participation at the broadest level, from the tasks of setting up a base to good old-fashioned field geology. In order to fulfill these activities, EVA suits for Mars exploration will need to support a 500 day Mars stay, be easy to maintain, fit a variety of crew members, and have sufficient mobility to easily tackle a variety of mission tasks. Although development has not yet started on an advanced planetary EVA system, we are using a variety of experimental suits to bound the requirements "space" for any new planetary surface suits. This work involves suited runs doing outpost set-up and geologic surface activities to evaluate the positive and negative aspects of each suit. This talk will discuss the requirements for EVA suit development, review the capabilities of the EVA suits developed for Apollo, and discuss the results of two field tests conducted in 1998 and 1999 in two different experimental suits
Theoretical studies of the impact environment prior to ~ 3.85 Ga tend to conclude that the Earth suffered repeated potentially sterilizing impact events, and that life could have originated - and then been annihilated - several or numerous times. The impact fluxes used are scaled from a crater density-time curve for lunar history that in fact is not constrained at times before 3.9 Ga. Mass accretion is better constrained, and demonstrates that at least the Nectarian-Early Imbrian time is anomalous in its high accretion rate. Sterilizing-scale impacts on Earth probably did not occur after ~ 4.3 Ga. The origin of life occurred in a comparatively quiescent impact environment.
The search for life elsewhere has become the intellectual centerpiece of NASA's space exploration program, and it is an issue that grabs the attention of the public in ways that few issues do. Why does astrobiology, and the exploration of the solar system and universe more generally, garner so much interest despite the complete lack of practical applications? What does it mean that we as a society are interested in the search for extraterrestrial life, and what would it mean to find it (or to search and not find it)? I will discuss the philosophical significance of the search for life elsewhere, the nature of historical sciences such as astrobiology and planetary science, the role of science in society and how it has evolved, and the importance of real outreach (as opposed to the "lip service" we are all expected to pay toward outreach).
The search for life on Mars has become a central focus of the planetary exploration program. I will discuss the scientific rationale for thinking that there could be life on Mars and the availability of geochemical resources to support life. In addition, I will discuss the search itself. Where should we send landers and rovers and, based on available geological, remote-sensing and in situ observations, what are we likely to find there? How will we identify martian life if it is different from terrestrial life? The answers to these questions are, unfortunately, neither simple nor straightforward, and we should recognize that a determination of whether Mars ever had life may be much more difficult than we imagine.
Although analogies between early Mars and the early Earth are frequently drawn they tend to be vague. New ideas about the tectonic evolution of the crust and about early life on Earth are emerging from recent investigations of three key areas: the Isua supracrustals on Greenland (3.7->3.8 b.y.), and the 3.3-3.5 b.y,-old greenstone belts of Barberton, South Africa and Pilbara, Australia This seminar will present my own personal understanding of terrestrial crustal evolution (assimilating evidence from the literature and latest discussions with other colleagues working in the field) as a backdrop for the appearance and evolution of life on Earth. New ideas about the distribution of early life and the relevance for it's formation will be presented. This new synthesis will then be compared to what is understood about the history of Mars.
We have begun to find the first true aqueous fluid inclusions in ordinary and carbonaceous chondrites. These fluid inclusions represent the first direct samples of the fluids that effected early aqueous alteration of asteroids. For the first time the possibility of doing direct work on this fluid, and thereby placing some constraints on the theory surrounding asteroidal alteration processes, presents itself. In addition, this water presents the first possibility of tracing the origins of water on Earth and in our solar system.
Ground-based telescopes are important tools for studying our solar system. However, the angular resolution of even the best telescopes is limited by atmospheric turbulence to ~0.5 arcseconds. Adaptive optics (AO) can overcome this limitation. The AO system on the 10-m W.M. Keck telescope can reach resolutions of 0.04 arcseconds or better - surpassing the Hubble Space Telescope and corresponding, for example, to 120 km on the surface of Io.
I will present three of the projects our group is carrying out using the Keck telescope. The first is near-IR imaging of volcanic hotpots on Io. The second is imaging of Titan, simultaneously measuring atmospheric properties and the surface albedo. The final project is an AO search for young extrasolar planets.
One of the more significant results from observational astronomy over the past decade has been the detection, via radial velocity studies, of apparent low mass companions (LMCs) to solar like stars. Radial velocity studies yield three pieces of information regarding the companions; their projected mass (Msini), and their orbital period and eccentricity. The commonly held interpretation of these objects is that they are "extrasolar planets", as contrasted to brown dwarfs or stellar companions. If this interpretation is correct, these discoveries would complete the Copernican Revolution. However, a statistical analysis of the two orbital observables strongly suggests that these companions have far more in common with binary companions than they do with planetary objects. Furthermore, estimations of true mass based on astrometric data indicate that significant percentage of apparent LMCs have actual masses in brown dwarf or even stellar range. In this context, the present, extensive theoretical effort to explain the properties of LMCs, driven entirely by the ad hoc assertion that these exciting newly discovered objects are planets, is quite reminiscent of the frantic generation of Ptolemaic epicycles to retain the dogma. This talk presents all, up to date observational facts about LMCs and offers an objective commentary.
The growth of Jupiter, as predicted by the favored core-accretion model of planetary formation, is a two-stage process. First a 10 Earth mass core is formed by runaway growth of an icy protoplanet, after which the protoplanet gravitationally captures over 300 Earth masses of gas directly from the Solar Nebula. The process is thought to take about 107 years. An alternate possibility, the mass-instability hypothesis, has recently experienced a resurgence of interest due to the increasingly rapid discoveries of unusual jovian-mass extrasolar planets. A sufficiently massive gas disk can become unstable and form a giant planet in as short as 100 years. Which process actually formed Jupiter? Trojan asteroids, very numerous and with close dynamical links to Jupiter, may provide the critical clues.
Since Mariner 9 returned the first images of dendritic-like networks of small valleys in the ancient cratered highlands of Mars, the resemblance of these features to terrestrial run-off channels has led to the frequent assertion that the planet's early climate must have been warm. However, the development of the valley networks under other environmental conditions appears equally probable. In this talk it is argued that the debate over whether the early Martian climate was warm or cold is ultimately unanswerable and effectively irrelevant to the development of the early hydrosphere and potential origin of life.
The origin and hydraulic implications of the "recent" high-latitude seepage features, identified by Malin and Edgett, will also be discussed.
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