LDEF Space Plasma-High Voltage Drainage Experiment post-flight results

The Space Plasma-High Voltage Drainage Experiment (SP-HVDE) was comprised of two identical experimental trays. With one tray located on the leading (ram facing, B10) edge and the other located on the trailing (wake facing, D4) edge of the Long Duration Exposure Facility (LDEF), it was possible to directly compare the effects of ram and wake spacecraft environments on charged dielectric materials. Six arrays of Kapton dielectric samples of 2 mil, 3 mil, and 5 mil thicknesses maintained at +/- 300, +/- 500, and +/- 1000 voltage bias formed the experimental matrix of each tray. In addition, each tray carried two solar cell strings, one biased at +300 volts and the other at -300 volts, to study current leakage from High Voltage Solar Arrays (HVSA). The SP-HVDE provides the first direct, long-term, in-flight measurements of average leakage current through dielectric materials under electric stress. The experiment also yields information on the long term stability of the bulk dielectric properties of such materials. Data and findings of the SP-HVDE are an extension of those from shorter term flight experiments such as the PIX-1 (Plasma Interaction Experiment) and PIX-2 and are therefore valuable in the design and evaluation of long-lived space systems with high voltage systems exposed to the low earth orbital environment. A summary of the SP-HVDE post flight analysis final report delivered to the LDEF Project Office under contract to the National Aeronautics and Space Administration is presented

Detection of Organic Constituents Including Chloromethylpropene in the Analyses of the ROCKNEST Drift by Sample Analysis at Mars (SAM)

key challenge in assessing the habitability of martian environments is the detection of organic matter - a requirement of all life as we know it. The Curiosity rover, which landed on August 6, 2012 in Gale Crater of Mars, includes the Sample Analysis at Mars (SAM) instrument suite capable of in situ analysis of gaseous organic components thermally evolved from sediment samples collected, sieved, and delivered by the MSL rover. On Sol 94, SAM received its first solid sample: scooped sediment from Rocknest that was sieved to <150 m particle size. Multiple 10-40 mg portions of the scoop #5 sample were delivered to SAM for analyses. Prior to their introduction, a blank (empty cup) analysis was performed. This blank served 1) to clean the analytical instrument of SAMinternal materials that accumulated in the gas processing system since integration into the rover, and 2) to characterize the background signatures of SAM. Both the blank and the Rocknest samples showed the presence of hydrocarbon components

Planning considerations related to the organic contamination of martian samples and implications for the Mars 2020 rover

© Copyright 2014, Mary Ann Liebert, Inc. Data gathered during recent NASA missions to Mars, particularly by the Rovers Spirit, Opportunity, and Curiosity, have provided important insights into the past history and habitability of the Red Planet. The Mars science community, via input through the National Research Council (NRC) Planetary Science Decadal Survey Committee, also identified the prime importance of a Mars sample return (MSR) mission to further exploration of the Red Planet. In response, the Mars 2020 Mission (Mars 2020) Science Definition Team (SDT) (Mustard et al., 2013) was chartered by the NASA Mars Exploration Program to formulate a new rover mission that would take concrete steps toward an eventual sample return. The SDT recommended that the 2020 rover should select and cache scientifically compelling samples for possible return to Earth. They also noted that organic contamination of the samples was a significant and complex issue that should be independently investigated by a future committee. Accordingly, NASA chartered the Mars 2020 Organic Contamination Panel (OCP). The OCP was charged with evaluating and recommending sample contamination requirements for the proposed Mars 2020. A further task was to assess implementation approaches in support of the investigation of broad scientific questions concerning the history and habitability of Mars. Central to these objectives would be the ability to reliably differentiate indigenous martian organic molecules from terrestrial contamination in any future samples returned from Mars. Early on during its deliberations, the OCP recognized that the scientific and planetary protection (PP) objectives of MSR are intimately linked, in that both rely heavily on measurements of organic molecules in the returned samples. In each case, a key aspect of the problem is being able to recognize and interpret organic molecules as indigenous to Mars against a potential background of Earthsourced contamination. It was within this context that the OCP committee considered the structure for a set of measurement goals related to organic molecules in the returned samples that would be of common interest to science and PP. The following is a summary of the most significant findings of the OCP regarding organic geochemical measurements that would be shared for both science and PP in relation to potential future MSR