Engineering topics
Publications and source records attributed to Agee, C. B..
Homestead L5 is a viable analog to martian mantle. High pressure phase relations help elucidate martian magmatic processes. Additional information is contained in the original extended abstract.
A suite of lunar soils has been investigated by imaging and in-situ spectroscopy techniques. A suite of contaminant plastics and potential microbes has been found. Additional information is contained in the original extended abstract.
The abundances of V, Cr, and Mn are similarly depleted in the Earth and Moon. We present metal/silicate partitioning results which examine if the depletions can be explained by a core formation event. Additional information is contained in the original extended abstract.
Low-level doped solid metal/liquid metal experiments analyzed by laser ablation ICP-MS allow Henry's Law to be tested. The results indicate Henry's Law is obeyed and the experimental partition coefficients can be applied to iron meteorites. Additional information is contained in the original extended abstract.
One explanation for Al and REE depletions in SNC meteorites is early majorite fractionation in a deep martian magma ocean. We report initial results from an experimental investigation of partitioning between majoritic garnet and ordinary chondrite liquid. Additional information is contained in the original extended abstract.
A sample return mission is an important next step in the exploration of Mars. The first sample return should come early in the program time-line because the science derived from earth-based analyses of samples provides crucial "ground truth" needed for further exploration planning, enhancement of remote measurements, and achieving science goals and objectives that include: (1) the search for environments that may support life and any indicators of the past or present existence of life, (2) understanding the history of water and climate on Mars, (3) understanding the evolution of Mars as a planet. Returned samples from Mars will have unique value because they can be studied by scientists worldwide using the most powerful analytical instruments available. Furthermore, returned Mars samples can be preserved for studies by future generations of scientists using new techniques and addressing new issues in Mars science. To ensure a high likelihood of success, the first sample return strategy should be simple and focused. We outline a fundamental set of sample requirements and acquisition priorities for Mars sample return.
Curation of Mars samples includes both samples that are returned to Earth, and samples that are collected, examined, and archived on Mars. Both kinds of curation operations will require careful planning to ensure that the samples are not contaminated by the instruments that are used to collect and contain them. In both cases, sample examination and subdivision must take place in an environment that is organically, inorganically, and biologically clean. Some samples will need to be prepared for analysis under ultra-clean or cryogenic conditions. Inorganic and biological cleanliness are achievable separately by cleanroom and biosafety lab techniques. Organic cleanliness to the <50 ng/sq cm level requires material control and sorbent removal - techniques being applied in our Class 10 cleanrooms and sample processing gloveboxes.
A prototype handling system to provide control of biological contamination of Earth by returned Mars samples while maintaining the chemical and biological integrity of those samples was designed, constructed and tested.
Element partitioning study provides a number of constraints on the formation and composition of the core. First, partitioning of siderophile elements between the core and mantle should explain the "excess" siderophile elements in the mantle. Second, partitioning of light element(s) between the core and mantle should supply the core with the right amount of light element(s) to account for the density deficit in the core. Third, partitioning of light element(s) between the inner and outer core should be consistent with the observed difference in density deficits (relative to pure Fe) between these two reservoirs. In this study, high-pressure and high-temperature experiments have been conducted to investigate the pressure, temperature, and composition effects on partitioning of siderophile elements Ni and Co between core-forming Fe alloy and mantle silicate melt and minerals, partitioning of light elements S, O, and Si between core-forming Fe alloy and mantle silicate melt and minerals, and partitioning of light elements S and C between solid and liquid Fe. The implications of these results for mechanism of core formation and the composition of the core are discussed.