LPI Seminar Series


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 held on Thursdays from 3:30-4:30 p.m. in the Lecture Hall at USRA/LPI, 3600 Bay Area Boulevard, Houston, Texas. A map of the Clear Lake area is available h​e​r​e​. Light refreshments are served at 4:30 p.m.

For more information, please contact Prajkta Mane (e-mail: pmane@lpi.usra.edu). The schedule is subject to revision.

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.

January 2019

Thursday, January 24, 2019 - Lecture Hall, 3:30 PM
Steven J Desch, Arizona State University
LPI Seminar: Ureilite Diamonds from Mars’s Core: A Tale of Three Planets, None of Them Lost

Recent analyses of mineral inclusions inside ~100 μm diamonds from the Almahata Sitta ureilite meteorite show they formed at pressures > 21 GPa, demanding origin inside a planet. We argue the diamonds are exogenous to the ureilite parent body (UPB) and instead formed at Mars’s core-mantle boundary. After floating to the top of Mars’s magma ocean, they and other materials were ejected in the Borealis basin impact early in Mars’s evolution. One fragment struck the UPB, which until then resembled other meteorite parent bodies like Vesta. The impact catastrophically disrupted the UPB. Mixing of Martian surface materials with the UPB material gave ureilites many of their unusual characteristics. We identify the asteroid 15 Eunomia as potentially the largest remnant of the collision, and 438 Zeuxo as a possible source of Almahata Sitta. We identify a dynamical pathway for delivery of ureilites to Earth. Ureilites may contain the only known samples of a planetary core.

February 2019

Tuesday, February 12, 2019 - Lecture Hall, 3:30 PM
Seungyeol Lee, University of Wisconsin-Madison
LPI Seminar: Application of Combined Techniques for Studying Nano-Minerals in Geological System

Modern technology allows us to detect, characterize, and understand the nature of nano-minerals. However, it is still challenging to determine its structure at the nanoscale when structures include the short-range ordering, defects, and local domains. I used integrated techniques (X-ray/Neutron diffraction, Pair distribution function, TEM, Z-contrast imaging) for solving this problem and applied some nano-minerals in geological environments. This presentation will several research examples: new nano-mineral observation (luogufengite and valleyite), crystal structure of minerals (6-line ferrihydrite, vernadite and low-temperature tridymite/cristobalite), nano-structure enhancing magnetic coercivity (lodestone and hemo-ilmenite).

Thursday, February 14, 2019 - Lecture Hall, 3:30 PM
Joelle Reiser, Pacific Northwest National Laboratory
LPI Seminar: Comparative Structural Investigations of Nuclear Waste Glass Alteration Layers and Sol-gel Synthesized Aerogels

Nuclear reactors provide reliable energy, but resultant nuclear waste requires safe disposal. Borosilicate glass is a current immobilization method, incorporating nuclear waste products into glass matrices. Understanding alteration mechanisms in aqueous media is essential to nuclear waste performance assessments to ensure radioisotopes are contained for extended periods of time. When exposed to aqueous solutions, borosilicate glass releases various ions into solution and alteration products (or alteration layers) are formed at the surface of glasses. Although the nuclear glass alteration community has agreed on the mechanisms during initial dissolution, the general mechanisms of the formation of alteration layers and their role in long-term glass alteration are still being debated. More information on physical properties of the alteration layers is needed to further the understanding of their impacts on overall glass alteration. In this work, pore volumes and solid structures of glass alteration layers formed in solutions of various pH conditions are evaluated with small angle X-ray scattering (SAXS). Solid structures of alteration layers are compared to those of synthetic aerogels of comparable compositions produced under various pH conditions. Alteration layers formed at pH 11 were shown to contain large structures (>10 nm) similar to synthetic aerogels created under neutral and basic conditions whereas alteration layers formed at pH 9 did not. The large structures formed at pH 11 are proposed to be caused by excessive free Si species through Ostwald Ripening.

Tuesday, February 19, 2019 - Lecture Hall, 3:30 PM
LPI Seminar: Alvaro Crósta (State University of Campinas, Brazil
The impact record of South and Central America: An updated review

The Earth’s impact record is known to be rather limited in both time and space. There are about 190 impact structures currently known on Earth, representing a minor fraction of all the impact events that contributed to the initial formation of our protoplanet, and then to formation and modification of the surface of the planet. Moreover, the distribution of impact structures on Earth is manifestly uneven. Two continents that stands out for their relatively small number of confirmed impact structures and impact ejecta occurrences are South and Central America. The limited impact record for this large continent makes a robust case that there is a significant potential for further discoveries. A summary of the current knowledge of the impact record of these continents will be presented covering also some occurrences of impact glasses in Argentina, Chile, Uruguay and, possibly, Colombia, as well as occurrences of distal deposits from the K-Pg boundary event that formed the Chicxulub structure in Mexico.

Monday, February 25, 2019 - Lecture Hall, 3:30 PM
Bradley J. Thomson, University of Tennessee
LPI Seminar: Crater-hosted Deposits on Mars and Moon: Targets for Science and Exploration

In this talk, I will discuss geologic context and history of materials with Gale crater on Mars and numerous polar craters on the Moon. In each case, we can analyze the present-day geology and geomorphology with a variety of techniques to infer elements of their past history. The Mars Science Laboratory rover Curiosity has been exploring the layered central mound within Gale crater on Mars from 2012 to the present. On the Moon, numerous impact structures near the lunar poles lie in permanent shadow and may host ice, although interpretations from several ground- and spacecraft-based observations diverge on the nature of these putative ice deposits.

March 2019

Tuesday, March 5, 2019 - Lecture Hall, 3:30 PM
Sally L. Potter-McIntyre, Southern Illinois University
LPI Seminar: Subsurface Habitability on Earth and Mars

The subsurface of Earth is a habitable environment that contains a large portion of the total biomass on this planet. Similarly, the subsurface of Mars may represent a past or even present habitable environment. Accessibility of the subsurface is challenging on both planets, but nevertheless, understanding the variability of subsurface fluids and water/rock/biota interactions occurring in these environments is crucial because this understanding informs both present conditions for habitability as well as the evolution of these environments over geologic time. Most terrestrial subsurface research focuses on drill cores, deep sea drilling, or cave or mine research; however, drilling and cave research are not likely to occur on Mars in the near future, so it is imperative that we are able to glean clues about the martian subsurface from surficial evidence. My research investigates ways to identify fingerprints of subsurface fluid/rock/biota in exposed examples and two case studies are presented: diagenetic jarosite, and magmatic intrusions into sulfur-rich sedimentary rocks.

Thursday, March 7, 2019 - Lecture Hall, 3:30 PM
Carly Howett, SWRI
LPI Seminar: 2014 MU69 - The first encounter with a cold classical Kuiper Belt Object

On the 1st of January 2019 NASA's New Horizons' spacecraft made its closest approach of 2014 MU69 (sometimes nicknamed simply MU69, or Ultima Thule). MU69 is a cold classical Kuiper Belt object, residing at 44.6 AU from the Sun, making it both the most distant object ever explored and also the most primitive. The images returned by New Horizons show MU69 to be a complex world: a contact binary ~31 km long, with two touching unequally sized lobes 19 km and 14 km wide that are flattened in one direction. The appearance of both lobes appears lumpy, dark, and uniform in color except in the neck region that links the lobes, which

Thursday, March 28, 2019 - Lecture Hall, 3:30 PM
Daniel Dunlap, Arizona State University
LPI Seminar: Chronology of Planetesimal Differentiation Based on Timing of Achondrite Formation in the Early Solar System.

Achondrites are igneous meteorites which record the earliest epoch of planetesimal melting and differentiation. Studying the chronology of achondrites is vital to understanding the timeline of accretion, differentiation, and subsequent reheating of planetesimals. Much of this activity was occurring early in Solar System history and over a relatively short period of time. In order to interrogate the timing of these events in sufficient detail, high resolution chronometers are used. Presented here are the results from investigations into the chronology of a selection of brachinites, eucrites, and ungrouped differentiated achondrites. In short, accretion and melting of various planetesimals began almost contemporaneously with formation of Calcium-Aluminum-rich Inclusions, evolved high-silica crustal compositions are possible on some planetesimals and their formation occurred concurrently with the earliest basaltic crusts, and some achondrites experienced protracted post formation thermal metamorphism. These findings provide critical constraints on the melting and subsequent evolution of achondrite parent bodies in the early Solar System.

April 2019

Monday, April 1, 2019 - Lecture Hall, 3:30 PM
Kennda L.Lynch, Georgia Institute of Technology
LPI Seminar: Subsurface, Subaqueous, and Salty: Looking for Life in all the right places

A key recommendation from the recent National Academies study on the state of astrobiology is that "NASA's programs and missions should reflect a dedicated focus on research and exploration of subsurface habitability in light of recent advances demonstrating the breadth and diversity of life in Earth's subsurface, the history and nature of subsurface fluids on Mars, and potential habitats for life on ocean worlds". Through my work, I seek to understand the diverse extent of environments on Earth in which life can survive within subsurface, subaqueous, and salty environments and how this translates to the type of habitable environments that are possible in our solar system and beyond and how we can detect and characterize signatures of life in these planetary environments.

Wednesday, April 3, 2019 - Lecture Hall, 3:00 PM
Germán Martínez Martínez, University of Michigan
LPI Seminar: Assessing the Habitability Potential of Mars and Beyond Through Mission Data Analysis, Numerical Modeling and Laboratory Experiments: Implications for Instrument Development

The search for life beyond Earth is a defining question for NASA's Research Programs. In the Solar System, Mars and Icy Worlds (e.g., Europa or Enceladus) are among the highest priority targets in the search for life because there is evidence that liquid water, a necessary ingredient for life as we know it, exists in their subsurface. In addition to liquid water, UV radiation is important for habitability because it can break down organic molecules. The search for life on these bodies will primarily be conducted by robotic exploration, but in the case of Mars it will be supported by human exploration likely to occur in the next few decades. I will discuss assessments of water resources and the radiative environment pertinent to the habitability potential of Mars using results from mission data analysis, laboratory experiments and numerical modeling. In addition, I will discuss innovative mission concepts and instrumentation aimed at searching for habitable environments on Mars and the Icy Worlds.

Thursday, April 4, 2019 - Lecture Hall, 3:30 PM
LPI Seminar: Carolyn Crow, University of Colorado Boulder
Apollo Zircons – A New Perspective on Lunar Crustal Evolution

Lunar zircons are among the oldest dated materials returned by the Apollo missions and contain one of the best records of crustal processes on the early Moon. Zircon has the unique ability to record signatures of both primary crystallization as well as a range of secondary alteration due to subsequent magmatism, impact shock, and regolith processes. We now have geochronologic, trace element, microtextural, and noble gas datasets for 100s of zircons separated from Apollo 14, 15, and 17 samples. In this presentation I will discuss the insights that these significant datasets give us about lunar crustal evolution, as well as highlight two new zircon studies that will help illudicate the post 3.9 Ga history of the Moon.

Thursday, April 18, 2019 - Lecture Hall, 3:30 PM
Jangmi Han, Lunar and Planetary Institute
LPI Seminar: Refractory Ca-Al-Rich Inclusions in Carbonaceous Chondrites – A Record of High-Temperature Events in the Early Solar Nebula.

Refractory Ca-Al-rich inclusions (CAIs) represent the oldest and most primitive objects that formed in the protoplanetary disk and hence pose crucial importance as recorders of processes and conditions during the early evolution of the Solar System. Importantly, CAIs consist of the first phases predicted by thermodynamic calculations to condense out of a gas of solar composition during cooling from very high temperatures. I will discuss fine scale mineralogical, chemical, and isotopic characteristics of CAIs in carbonaceous chondrites that help us gain a better understanding of how first solids formed and evolved by high-temperature processes, including condensation and gas-solid reactions, in the early solar nebula.

Thursday, April 25, 2019 - Lecture Hall, 3:30 PM
Samuel Crossley, University of Maryland
LPI Seminar: Understanding oxidized differentiation through the brachinites and implications for the oxidized bodies in the solar system

As part of our ongoing work in assessing the population and distribution of oxidized, olivine-dominated asteroids, I will present our recent findings with regard to the brachinite clan of meteorites. Generally, brachinites are thought to be residues from partial melting of precursors similar to Rumuruti-type (R) chondrites. Distinct trace element signatures for these types of meteorites provide insight into processes that occurred during the onset of differentiation for oxidized parent bodies, and help to resolve mineralogic and geochemical differences between brachinites and ungrouped “brachinite-like” primitive achondrites.

May 2019

Thursday, May 9, 2019 - Lecture Hall, 3:30 PM
William Banerdt, JPL
LPI Seminar: Early Results from the InSight Mission

In this talk I will discuss initial results from InSight’s measurements during the first ~150 sols on the surface, including meteorology, surface properties, geology, magnetics, and (of course) – seismology!

June 2019

Wednesday, June 5, 2019 - Lecture Hall, 3:30 PM
Bungo Shiotani, University of Florida
LPI Seminar: Project Life-Cycle and Implementation for a Class of Small Satellites

With advancements in miniaturization technologies, novel and innovative approaches to space and planetary explorations are being realized. An outcome of these innovations is a new class of small satellites referred to as CubeSats. CubeSats are popular within the space community due to their smaller form factor, lower costs, and faster development times as compared to traditional monolithic satellites. Currently, there are no project life-cycles that are suitable for CubeSat class satellites. For my dissertation, I developed a comprehensive project life-cycle for these CubeSat class satellites. The Containerized Satellite Mission Life-Cycle leverages appropriate aspects of various existing project life-cycles and engineering activities performed by the space/government agencies and the small satellite community. The efficacy of the project life-cycle is assessed through two applications, one is an actual small satellite mission known as SwampSat II and the other is a non-space mission known as DebriSat. In this presentation, the implementation of the project life-cycle to SwampSat II and DebriSat are shared.

Thursday, June 13, 2019 - Lecture Hall, 3:30 PM
Mini Wadhwa, ASU
LPI Seminar: Fire and Water on Vesta: Implications for the earliest volcanism and origin of water on asteroids

The asteroid Vesta is the second largest body (after Ceres) in the asteroid belt. It is one of the remnants left over from the earliest epoch in Solar System history that preceded the formation of the terrestrial planets, including Earth. Planetesimals like it likely contributed to the accretionary materials that formed the terrestrial planets. As such, understanding the sources of heat and volatiles (such as water) on this dwarf planet can potentially clarify the earliest formation conditions and volatile sources for the terrestrial planets. Although there have been no samples returned as yet from Vesta by spacecraft, a particular group of meteorites (called the eucrites) are thought to originate in the crust of this asteroid. These meteorites effectively represent a free “sample return mission” that likely occurred when these samples were excavated by an impact that created the Rheasilvia basin on Vesta. In this talk, I will discuss results of work that we have done on a rare unequilibrated eucrite to better understand the timing of the earliest volcanism on Vesta. I will also talk about our work on determining hydrogen isotopes and the abundance of water in several other eucrites that has implications for the source and the water budget on this asteroid – this in turn has implications for the source of water on planets, like Earth and Mars, in the inner Solar System.

Tuesday, June 25, 2019 - Lecture Hall, 3:30 PM
Jennifer Gorce, Virigina Tech
Advances in constraining the Pressure-Temperature-time (P-T-t) paths of subducted lithologies and their application to planetary science

The metamorphic reactions that occur during prograde metamorphism are dehydration reactions, and thus, metamorphism strongly influences the global geohydrologic cycle. At subduction zones, fluid release is of particular importance because the interaction between the cold, hydrated down-going slab and the hot, anhydrous overlying mantle lead to complex chemical, physical and thermal mixing that has important implications for mantle rheology, elemental cycling, and the thermal evolution of the planet. In order to better understand and constrain these large scale processes, it is important to elucidate the Pressure-Temperature-time (P-T-t) paths of subducted lithologies. Modeling thermodynamic phase equilibria of subducted lithologies in conjunction with detailed petrography is a valuable tool for constructing P-T-t paths, and the methodologies utilized could have novel application to the study of meteoric materials. This talk will focus on integrating computational thermodynamic modeling, Sm/Nd garnet geochronology, and detailed chemical and petrographic observations to better constrain the P-T-t paths of subducted lithologies. I will also discuss how methodologies utilized in this study can be applied to planetary studies to better understand the evolution of early planetary bodies and mafic crust formation.

Thursday, June 27, 2019 - Lecture Hall, 3:30 PM
Kelsey Prissel, Washington University in St. Louis
Isotopic evolution of the lunar magma ocean and implications for mare basalt source regions

High-precision, non-traditional stable isotope analyses of lunar samples have recently provided new compositional constraints for the petrologic history of the Moon and lunar volcanism. In particular, resolvable differences exist between the Fe, Ti, and Mg isotopic compositions of the low-Ti and high-Ti mare basalts. Ilmenite (FeTiO3) has been hypothesized to fractionate Fe and Ti isotopes in lunar magmas. If ilmenite fractionates isotopes during crystallization, then late-stage precipitation of ilmenite from the lunar magma ocean (LMO) may explain the variable isotopic compositions of the mare basalts and the correlation between mare basalt isotopic composition and Ti content. Similarly, the Fe isotopic composition of lunar dunite 72415 has been interpreted as evidence for isotopic fractionation during extensive olivine crystallization early in the LMO. In this talk, I will present experimentally-determined mineral-melt Fe isotopic fractionations for olivine and ilmenite and incorporate these fractionations into models of LMO crystallization. I will then compare the isotopic compositional evolution of the LMO liquid and cumulates to the observed isotopic compositions of the mare basalts to address to what extent the observed isotopic variability of the lunar mare basalts can be explained by LMO processes.

July 2019

Thursday, July 25, 2019 - Lecture Hall, 3:30 PM
Álvaro Vicente-Retortillo, University of Michigan
UV radiation measurements on Mars: Implications for future robotic exploration and habitability

The Rover Environmental Monitoring Station (REMS) of the Mars Science Laboratory (MSL) mission has a sensor that has been measuring UV radiation for the first time at the Martian surface. These measurements, which currently cover more than six years, provide useful insights for the future exploration of the planet. On one hand, dust accumulated on the sensor follows a seasonal cycle with a dust removal season [1]. This periodical removal of dust indicates that solar energy can be used to power long missions. On the other hand, measurements in the UVB and UVC bands indicate that the radiative environment is extremely adverse for life. Therefore, as shown recently [2], materials that are opaque to UV radiation would become necessary to make some Mars regions potentially habitable. [1] Vicente-Retortillo, A., et al. Scientific Reports, 8, 17576, 2018. [2] Wordsworth, R., et al. Nature Astronomy, 2019, DOI: 10.1038/s41550-019-0813-0

October 2019

Friday, October 4, 2019 - Lecture Hall, 3:30 PM
Astrid Holzheid, Institute of Geosciences, University of Kiel
The Fate of Platinum Group Elements (PGE) During Mantle Melting

Opposing trends of the PGE pattern of primitive mantle melts and of peridotite-xenoliths are observed worldwide. The most likely processes of PGE fractionation during mantle melting will be discussed in due consideration of various physico-chemical interaction processes between coexisting silicate, solid sulfide and liquid sulfide phases. It is possible to link the distinct different PGE pattern of primitive mantle melts and of peridotite-xenoliths to 'simple' mantle melting processes.

Thursday, October 17, 2019 - Lecture Hall, 3:30 PM
Benjamin F. Feist
Apollo in Real Time - How Apollo History is Helping to Pave the Way for NASA’s Future

This year is the 50th anniversary of the first time humanity set foot upon the Moon. Digitizing the historical material on the Apollo program has been a major undertaking that enables the material to be expressed through new interactive experiences, presented raw in its original glory. Learn how we presented Apollo history using this new concept of "no-narrative" storytelling in both, the IMAX film Apollo 11, and the apolloinrealtime.org interactive website. The historical record of the Apollo Program is being leveraged in new ways to help NASA to plan for the next 30 years of space exploration. See how these visualizations are being applied to modern mission analogs and are contributing to plans for future space exploration.

Previous Seminars

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