In its eighteenth year, the LPI Summer Intern Program offers selected undergraduate students an opportunity to participate in lunar and planetary science research at the Institute and the NASA Johnson Space Center. The 1994 program begins on June 13 and ends August 19. For more information or to apply for internship next year, contact LPI Summer Intern Program, 3600 Bay Area Boulevard, Houston TX 77058-1113.

KOOROSH ARAGHI, University of Arizona

Advisors: Carlton C. Allen and Tom Sullivan, NASA Johnson Space Center

Mars sample return, piloted Mars missions, and advanced life support systems on long- duration spacecraft will all need technologies to process CO2 into needed materials such as oxygen, water, methane, etc. For planetary missions, using the resources already in space can lower the launch mass (and thus cost) more dramatically than any other technology. The objective of this project is to build and operate a reactor (breadboard) to convert CO2 and H2 into CH4 and O2. Existing membranes can process CO2, the major component of the martian atmosphere, to O and CO. The production of CH4 using similar membranes was recently demonstrated at Stanford University. The basic components of the system already exist and will be assembled into a working unit. Parameters such as temperature, flow rate, and pressure will be optimized to understand how the process can contribute to Mars missions by producing the propellant required for the trip home. An advantage of this technology is that a single reactor could replace three separate systems: a Sabatier reactor, and water and CO2 electrolysis units. There are also potential uses at a lunar outpost.

KRISTIN M. BURGESS, Wesleyan University

Advisors: Fred Horz and Michael Zolensky, NASA Johnson Space Center

The aim of this project is to characterize the size frequency distribution of all penetration holes in LDEF thermal blankets for the three cardinal viewing directions: leading, trailing, and space facing. These blankets are some 200 micrometers thick and penetration holes smaller than target thickness occur, but they are rare. Instead, one observes mostly craters at diameters < 200 micrometers. It is necessary to measure the "large" members of this crater population because the transition from cratering to penetration, at constant target thickness, is velocity dependent. Exact observations related to this transition may lead to improved estimates for mean encounter velocities, a novel approach that would complement the otherwise strictly theoretical considerations based on orbital dynamics.

KELLY H. FUKS, Georgia State University

Advisors: Allan Treiman and Scott Murchie, Lunar and Planetary Institute

The walls of the Valles Marineris canyons on Mars are steep scarps up to 8 km high, and provide a unique view of the subsurface geology of the planet. In the uppermost 1 km of the scarps are horizontal layers of resistant rock. There are up to eight successive layers, and some layers seem to reach for hundreds of kilometers. The layers might be basalt flows, erosional terraces, or "caliche" layers from ancient groundwater or ground ice. In this research project, the intern would try to discover the origin of the layers by detailed mapping from Mariner and Viking spacecraft images. Products of the research will include maps, geological cross sections, and a written paper.

TERESA HOLLOWAY, Brown University

Advisors: Michael J. Golightly, NASA Johnson Space Center, Mark D. Weyland, Space Systems Division, Rockwell International, and Gautam D. Badhwar, NASA Johnson Space Center

This project will seek to determine the drift rate of the South Atlantic Anomaly (SAA). The SAA is a region of space over the southern Atlantic ocean where geomagnetically trapped protons extend down to altitudes characteristic of shuttle missions. The SAA is an important source of radiation exposure for astronauts and payloads in low Earth orbit; accurate knowledge of the SAA's location is essential for flight planning and payload operation purposes. The drift rate of the SAA will be determined by analyzing measurements made with the Radiation Monitoring Equipment III during 14 shuttle missions. The measurements will be mapped and smoothed into a geographic coordinate system. The location of the maximum flux will be determined by fitting the smoothed data with a two-dimensional Gaussian fit. The location of the maximum SAA flux in 1970 will be calculated from the AP8 solar maximum trapped proton model. The drift rate will then be determined based on the difference between the measured and calculated maximum flux locations and the epoch of the datasets and the AP8 model.


Advisor: Paul Schenk, Lunar and Planetary Institute

Cratering is one of the most dominant geologic processes in the solar system. The icy satellites represent (among other things) a natural laboratory in impact mechanics and the role of gravity and composition. This study will investigate the importance of gravity in controlling the ejection of material out of craters onto the surface. One theory suggests that the extent of ejecta deposits is proportional to crater diameter, but that this relationship varies inversely with the surface gravity of the planets. We will test this hypothesis. The extent of continuous ejecta deposits will be mapped, based on criteria developed as a result of terrestrial planet studies, and their dimensions measured. Satellites for which data exist include Ganymede, Callisto, Rhea, Ariel, Dione, Miranda, and perhaps Callisto. This represents a factor of 100 in variation in surface gravity. Correction will also be made to account for the widening of the original transient crater diameter due to slumping. These results will then be compared with similar measurements for the Moon and Mercury to determine the "impact" of the icy vs. rocky composition on this process. We will then use the scaling relationships to determine the diameters of palimpsests and other poorly preserved impact features on Ganymede.

MICAH SHANE JOHNSON, Indiana University

Advisor: Walter S. Kiefer, Lunar and Planetary Institute

The Tharsis province of Mars contains many extensional features that are related to the uplift of the province, but there is considerable regional variation in the amount and style of this extension. These variations probably reflect regional variations in the lithosphere's vertically integrated strength and hence may be due to regional variations in crustal thickness and thermal gradient. The intern will model the relationship between extension and lithospheric strength and use the results of the model to constrain the allowed crustal thickness and thermal gradient. The results of this study will be compared with estimates of these quantities as derived from an inversion of gravity and topography data in order to determine if a self-consistent model can be found.

TRACY JOHNSTON, Wellesley College

Advisor: Gary Lofgren, NASA Johnson Space Center

The intern will examine the petrography of the chondrules in several type 3 and type 4 enstatite chondrites. The chondrule texture types will be determined, described, and classified. The natural chondrules will be compared to already completed experiments (Lofgren and Lanier, 1991). The results of these comparisons will be used to (1) formulate a formational history for enstatite chondrite chondrules and (2) compare enstatite chondrites to ordinary chondrites.

KARLA E. KUEBLER, University of Kansas

Advisor: Graham Ryder, Lunar and Planetary Institute

Lunar sample 72255 was broken from a boulder that had rolled down the slopes of the South Massif at the Apollo 17 landing site. It is a fine-grained impact melt containing a wide variety of small rock fragments. Subsets of these fragments have already been selected for chemical analysis and geochronological studies. The intern will contribute to our understanding of the origin of these fragments by making petrographic observations and microprobe analyses of mineral phases within them and making comparisons among the fragments and with other known lunar lithologies. Instruction in the necessary microscope, microprobe, and data presentation techniques will be provided.

SUZANNE N. LYONS, Texas A& M University

Advisor: Robert Herrick, Lunar and Planetary Institute

Several properties of complex impact craters (e.g., onset of central peaks, crater depth, etc.) have a strong dependence on target characteristics such as gravity, density, and target strength. Previous approaches to determining the nature of this dependence involved creating a forward model and demonstrating that its predicted results fit within the error tolerances of existing data. Recent compilations of morphometric data from Venus and the icy satellites have greatly expanded the range of target conditions, and it is now possible to let the data themselves determine the functional relationship of crater properties with target properties. The student will synthesize existing morphometric datasets and use standard inversion techniques to determine the dependence of complex crater formation on target gravity, density, and strength, and the relative strengths of planetary crusts.

KIMIYASU SATO, University of Tokyo

Advisor: Michael Zolensky, NASA Johnson Space Center, and Clyde Sapp, Lockheed Engineering & Science Co.

We propose to (1) obtain backscattered SEM images of thin-sectioned chondritic interplanetary dust particles (IDPs), (2) digitize each image, and (3) use the images and existing image software to determine the modal percentage of important mineral constituents and pores. This information will enable us to search for correlations between physical properties of the IDP parent bodies and their mineralogy.

KAREN R. STOCKSTILL, Ohio Wesleyan University

Advisor: Faith Vilas, NASA Johnson Space Center

C-class asteroids probably underwent aqueous alteration during their history in the solar system. Spectral reflectance studies in the visible and near-infrared have identified absorption features similar to those seen in laboratory reflectance spectra of phyllosilicates. This project will require the study of a large number of telescopic narrowband CCD reflectance spectra of asteroids, identifying and removing effects on the data, identifying trends within the data, and studying these trends in the context of solar system compositional formation.

PATRICK VALAGEAS, Paris University

Advisor: Tomasz F. Stepinski, Lunar and Planetary Institute

This project will examine the aerodynamics of solids in viscous protoplanetary disks. The seeds of the planetary system architecture are to be found in the radial distribution of solids in an accretion protoplanetary disk. The distribution of solid particles undergoes global time evolution, which accompanies, but is not identical to, the global time evolution of the gaseous component of the disk. This project concentrates on calculating space-time distribution of relative velocities of solids with respect to the gas. The evolution of the gas is calculated using the numerical code developed for viscous accretion disks. The result of the project will be a computer program that will start from given initial conditions and compute the time evolution of relative velocities between the gas and solid particles of different sizes. Such a program could be later incorporated into solid evolution models.