Wright, I. | Search NASA

NASA NTRS2018

Primitive Oxygen-, Nitrogen-, and Organic-Rich Vein Preserved in a Xenolith Hosted in the Metamorphosed Carancas Meteorite

Primitive xenolithic CI-like carbonaceous (C) clasts are sometimes hosted within meteorites of a different origin (ordinary chondrite, ureilite, howardite, and eucrite). These xenoliths contain aggregates of macromolecular carbon (MMC), which are often present as discrete grains and exhibit a wide range of structural order and chemical compositions. The Carancas meteorite is a H4-5 that impacted south of Lake Titicaca, Peru in 2007. While the meteorite exhibits extensive recrystallization of the matrix indicating metamorphism, it contains dark, CI-like clasts that show no evidence of heating. Similar to other xenolithic clasts, the examined C clast of Carancas contains MMC, which however exists in the form of a vein-like structure dissimilar to the typical occurrence of MMC in meteorites. We investigated the organic and isotopic compositions of the organic-rich vein with C,N,O-X-ray absorption near-edge structure (XANES), Raman spectroscopy, and NanoSIMS, in order to constrain its possible origin.

Chan, Q. H. S.↗

NASA NTRS2004

A Subsurface Soil Composition and Physical Properties Experiment to Address Mars Regolith Stratigraphy

Previous in-situ measurements of soil-like materials on the surface of Mars, in particular during the on-going Mars Exploration Rover missions, have shown complex relationships between composition, exposure to the surface environment, texture, and local rocks. In particular, a diversity in both compositional and physical properties could be established that is interpreted to be diagnostic of the complex geologic history of the martian surface layer. Physical and chemical properties vary laterally and vertically, providing insight into the composition of rocks from which soils derive, and environmental conditions that led to soil formation. They are central to understanding whether habitable environments existed on Mars in the distant past. An instrument the Mole for Soil Compositional Studies and Sampling (MOCSS) - is proposed to allow repeated access to subsurface regolith on Mars to depths of up to 1.5 meters for in-situ measurements of elemental composition and of physical and thermophysical properties, as well as for subsurface sample acquisition. MOCSS is based on the compact PLUTO (PLanetary Underground TOol) Mole system developed for the Beagle 2 lander and incorporates a small X-ray fluorescence spectrometer within the Mole which is a new development. Overall MOCSS mass is approximately 1.4 kilograms. Taken together, the MOCSS science data support to decipher the geologic history at the landing site as compositional and textural stratigraphy if they exist - can be detected at a number of places if the MOCSS were accommodated on a rover such as MSL. Based on uncovered stratigraphy, the regional sequence of depositional and erosional styles can be constrained which has an impact on understanding the ancient history of the Martian near-surface layer, considering estimates of Mars soil production rates of 0.5... 1.0 meters per billion years on the one hand and Mole subsurface access capability of approximately 1.5 meters. An overview of the MOCSS, XRS instrument accomodation and the impact that these instruments have on Mars science is discussed.

Richter, L.↗