MINERAL ANALYSIS OF APOLLO 17 SAMPLES FROM THE TAURUS-LITTROW VALLEY LANDSLIDE

The Apollo 17 mission returned double drive tube cores 73001/73002 collected as part of a series of samples taken from a landslide on the South Massif Wall of the Taurus-Littrow Valley, the floor of which is composed of mare basalt. Sample 73001 was obtained from this landslide, placed in a vacuum sealed container and stored at -25ºC. Fifty years later, it was opened as part of the Apollo Next Generation Sample Analysis Program (ANGSA). ANGSA was formed for the purpose of better understanding the Apollo 17 materials using technology not available in the 1970s. The Moon United Team, based out of NASA’s Goddard Space Flight Center, seeks to better understand the mineral, noble gas, and volatile content, as well as the cosmic ray exposure of the returned regolith.

Soil samples from the 73001 core allocated to the Moon United team were split to allow both sample characterization and noble gas analyses. Samples selected for characterization were prepared as polished grain mounts. Split 73001,364_A1 was selected for this study due to its dense population of uniformly-sized, fine-grained soil particles (generally 10-40 mm in size). An initial backscattered electron (BSE) mosaic of this grain mount was created, from which individual frames (at 692x, horizontal field width 393 mm) were examined in a systematic fashion. Individual spot compositional analyses were obtained of grains over ~10 mm in size using Energy Dispersive Spectroscopy (EDS) on the FEI Nova Nano-SEM 600 at the Smithsonian Institution. Each particle was then characterized based on composition and texture, as a mineral fragment, spherule, agglutinate, soil particle, etc. Overall, 168 mosaic frames were examined, and 1620 point analyses were obtained/particles were characterized. Of these, 39% were feldspar, 10% pyroxene, 7% olivine, 1% ilmenite + sulfide, 43% were fused soil components (including agglutinates), and 1% other. At first pass, this sample was more mafic than classified soil sample 72501 (collected from within the same landslide, but closer to the base of the South Massif Wall and characterized soon after Apollo 17 sample return), with ~14% more olivine and pyroxene fragments found in 73001 than in 72501, though both contained a similar abundance of fused soil components. This soil characterization will inform noble gas analyses of these materials.