LPI Seminar Series
LPI seminars will be held on Thursdays.
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 Martin Schmieder (phone: 281-486-2116; e-mail: email@example.com) or Nick Castle (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.
Join the LPI-Seminars mailing list to receive email notifications about upcoming LPI Seminars. To join the mailing list please send an email to:
- Thursday, September 27, 2018 - Lecture Hall, 3:30 PM
LPI Seminar: Desiree Cotto Figueroa, University of Puerto Rico
Scale-Dependent Measurements of Meteorite Strength and the Implications for Asteroid Fragmentation
Measuring the strengths of asteroidal materials is important for developing mitigation strategies for potential Earth impactors and for understanding properties of in situ materials on asteroids during human and robotic exploration. Studies of asteroid disruption and fragmentation have typically used the strengths determined from terrestrial analog materials, although questions have been raised regarding the suitability of these materials. The few published measurements of meteorite strength are typically significantly greater than those estimated from the stratospheric breakup of meter-sized meteoroids. Given the paucity of relevant strength data, the scale-varying strength properties of meteoritic and asteroidal materials are poorly constrained. Based on our uniaxial failure studies of centimeter-sized cubes of a carbonaceous and ordinary chondrite, we develop the first Weibull failure distribution analysis of meteorites. This Weibull distribution projected to meter scales, overlaps the strengths determined from asteroidal airbursts and can be used to predict properties of to the 100 m scale. In addition, our analysis shows that meter-scale boulders on asteroids are significantly weaker than small pieces of meteorites, while large meteorites surviving on Earth are selected by attrition. Further, the common use of terrestrial analog materials to predict scale-dependent strength properties significantly overestimates the strength of meter-sized asteroidal materials and therefore is unlikely well suited for the modeling of asteroid disruption and fragmentation. Given the strength scale-dependence determined for carbonaceous and ordinary chondrite meteorites, our results suggest that boulders of similar composition on asteroids will have compressive strengths significantly less than typical terrestrial rocks
- Thursday, October 11, 2018 - Lecture Hall, 3:30 PM
Frances Rivera-Hernandez, Dartmouth College
LPI Seminar: Lakes, Rivers, and Dry Landscapes in Gale Crater, Mars: The Importance of Understanding Grain Size Variations
Reconstructing ancient depositional environments is key to accomplishing the main goal of the Mars Science Laboratory mission: to characterize habitable environments of early Mars from the sedimentary record in Gale crater with the Curiosity rover. Accurate measurement of the size and distribution of grains in sedimentary rocks is crucial for interpreting depositional environment. This is a challenging task on Mars using rover images. However, grain size can be inferred from ChemCam Laser Induced Breakdown Spectroscopy data using the Gini Index Mean Score (GIMS), a statistical measure of compositional variability. > Results using the GIMS suggest that rocks in Gale crater from the ~5.2 m thick Yellowknife Bay formation consist of mudstones overlain by poorly sorted sandstones, demonstrating that flow characteristics shifted abruptly from a low-energy lake to a high energy alluvial environment. In contrast, GIMS results suggest that the ~300-m thick Murray formation consists primarily of mudstones with intervals of fine to coarse sandstones. While the interstratified sandstones indicate rapid fluid flow either in aeolian or fluvial environments, the persistence of mudstones suggest that lakes may have been sustained in Gale crater for tens of thousands to millions of years. Early Mars must have had climatic conditions that could have sustained the diversity of depositional environments preserved in Gale Crater.
- Thursday, November 8, 2018 - Lecture Hall, 3:30 PM
Simon Lock, Harvard University
LPI Seminar: TBD
- Friday, November 16, 2018 - Lecture Hall, 3:30 PM
Frances Bagenal, University of Colorado
LPI Seminar: Juno’s Exploration of the Giant Magnetosphere of Jupiter
Jupiter is a planet of superlatives: the most massive planet in the solar system, rotates the fastest, has the strongest magnetic field, and has the most massive satellite system of any planet. These unique properties lead to volcanoes on Io and a population of energetic plasma trapped in the magnetic field that provides a physical link between the satellites, particularly Io, and the planet Jupiter. There are strong differences between the magnetospheres of Earth and Jupiter but there are also underlying basic physical principles that all magnetospheres share in common. This presentation shows how measurements to be made by NASA’s Juno mission addresses these issues. And, if there is time and interest, I will discuss some interesting demographical studies of the physical sciences.
- Thursday, December 6, 2018 - Lecture Hall, 3:30 PM
Bill Stone, Stone Aerospace, Austin, TX
LPI Seminar: TBD