D. P. Glavin

Volatile, Isotope, and Organic Analysis of Martian Fines with the Mars Curiosity Rover

Samples from the Rocknest aeolian deposit were heated to ~835°C under helium flow and evolved gases analyzed by Curiosity’s Sample Analysis at Mars instrument suite. H2O, SO2, CO2, and O2 were the major gases released. Water abundance (1.5 to 3 weight percent) and release temperature suggest that H2O is bound within an amorphous component of the sample. Decomposition of fine-grained Fe or Mg carbonate is the likely source of much of the evolved CO2. Evolved O2 is coincident with the release of Cl, suggesting that oxygen is produced from thermal decomposition of an oxychloride compound. Elevated δD values are consistent with recent atmospheric exchange. Carbon isotopes indicate multiple carbon sources in the fines. Several simple organic compounds were detected, but they are not definitively martian in origin.

Curiosity at Gale Crater, Mars: Characterization and Analysis of the Rocknest Sand Shadow

The Rocknest aeolian deposit is similar to aeolian features analyzed by the Mars Exploration Rovers (MERs) Spirit and Opportunity. The fraction of sand <150 micrometers in size contains ~55% crystalline material consistent with a basaltic heritage and ~45% x-ray amorphous material. The amorphous component of Rocknest is iron-rich and silicon-poor and is the host of the volatiles (water, oxygen, sulfur dioxide, carbon dioxide, and chlorine) detected by the Sample Analysis at Mars instrument and of the fine-grained nanophase oxide component first described from basaltic soils analyzed by MERs. The similarity between soils and aeolian materials analyzed at Gusev Crater, Meridiani Planum, and Gale Crater implies locally sourced, globally similar basaltic materials or globally and regionally sourced basaltic components deposited locally at all three locations.

The imprint of atmospheric evolution in the D/H of hesperian clay minerals on Mars

Of water and methane on Mars The Curiosity rover has been collecting data for the past 2 years, since its delivery to Mars (see the Perspective by Zahnle). Many studies now suggest that many millions of years ago, Mars was warmer and wetter than it is today. But those conditions required an atmosphere that seems to have vanished. Using the Curiosity rover, Mahaffy et al. measured the ratio of deuterium to hydrogen in clays that were formed 3.0 to 3.7 billion years ago. Hydrogen escapes more readily than deuterium, so this ratio offers a snapshot measure of the ancient atmosphere that can help constrain when and how it disappeared. Most methane on Earth has a biological origin, so planetary scientists have keenly pursued its detection in the martian atmosphere as well. Now, Webster et al. have precisely confirmed the presence of methane in the martian atmosphere with the instruments aboard the Curiosity rover at Gale crater. Science, this issue p. 412, p. 415; see also p. 370 A measurement with the Curiosity rover probes the Hesperian era and constrains the timing of hydrogen loss. [Also see Perspective by Zahnle] The deuterium-to-hydrogen (D/H) ratio in strongly bound water or hydroxyl groups in ancient martian clays retains the imprint of the water of formation of these minerals. Curiosity’s Sample Analysis at Mars (SAM) experiment measured thermally evolved water and hydrogen gas released between 550° and 950°C from samples of Hesperian-era Gale crater smectite to determine this isotope ratio. The D/H value is 3.0 (±0.2) times the ratio in standard mean ocean water. The D/H ratio in this ~3-billion-year-old mudstone, which is half that of the present martian atmosphere but substantially higher than that expected in very early Mars, indicates an extended history of hydrogen escape and desiccation of the planet.

Evolved gas analyses of sedimentary rocks and eolian sediment in Gale Crater, Mars: Results of the Curiosity rover's sample analysis at Mars instrument from Yellowknife Bay to the Namib Dune

The Sample Analysis at Mars instrument evolved gas analyzer (SAM-EGA) has detected evolved water, H2, SO2, H2S, NO, CO2, CO, O2 and HCl from two eolian sediments and nine sedimentary rocks from Gale Crater, Mars. These evolved gas detections indicate nitrates, organics, oxychlorine phase, and sulfates are widespread with phyllosilicates and carbonates occurring in select Gale Crater materials. Coevolved CO2 (160 ± 248 - 2373 ± 820 μgC(CO2)/g), and CO (11 ± 3 - 320 ± 130 μgC(CO)/g) suggest organic-C is present in Gale Crater materials. Five samples evolved CO2 at temperatures consistent with carbonate (0.32± 0.05 - 0.70± 0.1 wt.% CO3). Evolved NO amounts to 0.002 ± 0.007 - 0.06 ± 0.03 wt.% NO3. Evolution of O2 suggests oxychlorine phases (chlorate/perchlorate) (0.05 ± 0.025 - 1.05 ± 0.44wt. % ClO4) are present while SO2 evolution indicates the presence of crystalline and/or poorly crystalline Fe- and Mg-sulfate and possibly sulfide. Evolved H2O (0.9 ± 0.3 - 2.5 ± 1.6 wt.% H2O) is consistent with the presence of adsorbed water, hydrated salts, interlayer/structural water from phyllosilicates, and possible inclusion water in mineral/amorphous phases. Evolved H2 and H2S suggest reduced phases occur despite the presence of oxidized phases (nitrate, oxychlorine, sulfate, carbonate). SAM results coupled with CheMin mineralogical and APXS elemental analyses indicate that Gale Crater sedimentary rocks have experienced a complex authigenetic/diagenetic history involving fluids with varying pH, redox, and salt composition. The inferred geochemical conditions were favorable for microbial habitability and if life ever existed, there was likely sufficient organic-C to support a small microbial population.

Biological contamination studies of lunar landing sites: implications for future planetary protection and life detection on the Moon and Mars

Chemical and microbiological studies of the impact of terrestrial contamination of the lunar surface during the Apollo missions could provide valuable data to help refine future Mars surface exploration plans and planetary protection requirements for a human mission to Mars. NASA and ESA have outlined new visions for solar system exploration that will include a series of lunar robotic missions to prepare for and support a human return to the Moon, and future human exploration of Mars and other destinations. Under the Committee on Space Researchs (COSPARs) current planetary protection policy for the Moon, no decontamination procedures are required for outbound lunar spacecraft. Nonetheless, future in situ investigations of a variety of locations on the Moon by highly sensitive instruments designed to search for biologically derived organic compounds would help assess the contamination of the Moon by lunar spacecraft and Apollo astronauts. These studies could also provide valuable ‘ground truth’ data for Mars sample return missions and help define planetary protection requirements for future Mars bound spacecraft carrying life detection experiments.

MOMA: The Challenge to Search for Organics and Biosignatures on Mars

This paper describes strategies to search for, detect, and identify organic material on the surface and subsurface of Mars. The strategies described include those applied by landed missions in the past and those that will be applied in the future. The value and role of ESAs ExoMars rover and of her key science instrument Mars Organic Molecule Analyzer (MOMA) are critically assessed.

Measurements of Oxychlorine species on Mars

Mars landed and orbiter missions have instrumentation capable of detecting oxychlorine phases (e.g. perchlorate, chlorate) on the surface. Perchlorate (*0.6 wt%) was first detected by the Wet Chemistry Laboratory in the surface material at the Phoenix Mars Landing site. Subsequent analyses by the Thermal Evolved Gas Analyser aboard the same lander detected an oxygen release (*465°C) consistent with the thermal decomposition of perchlorate. Recent thermal analysis by the Mars Science Laboratory’s Sample Analysis at Mars instrument has also indicated the presence of oxychlorine phases (up to 1.2 wt%) in Gale Crater materials. Despite being at detectable concentrations, the Chemistry and Mineralogy (CheMin) Xray diffractometer has not detected oxychlorine phases. This suggests that Gale Crater oxychlorine may exist as poorly crystalline phases or that perchlorate/chlorate mixtures exist, so that individual oxychlorine concentrations are below CheMin detection limits (*1 wt%). Although not initially designed to detect oxychlorine phases, reinterpretation of Viking Gas Chromatography/Mass Spectrometer data also suggest that oxychlorine phases are present in the Viking surface materials. Remote near-infrared spectral analyses by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) instrument indicate that at least some martian recurring slope lineae (RSL) have spectral signatures consistent with the presence of hydrated perchlorates or chlorates during the seasons when RSL are most extensive. Despite the thermal emission spectrometer, Thermal Emission Imaging System, Observatoire pour la Minéralogie, l’Eau, les Glaces et l’Activité and CRISM detection of hundreds of anhydrous chloride (*10–25 vol%) deposits, expected associated oxychlorine phases (>5–10 vol%) have not been detected. Total Cl and oxychlorine data sets from the Phoenix Lander and the Mars Science Laboratory missions could be used to develop oxychlorine versus total Cl correlations, which may constrain oxychlorine concentrations at other locations on Mars by using total Cl determined by other missions (e.g. Viking, Pathfinder, MER and Odyssey). Development of microfluidic or ‘lab-on-a-chip’ instrumentation has the potential to be the next generation analytical capability used to identify and quantify individual oxychlorine species on future landed robotic missions to Mars. Received 19 August 2015, accepted 8 February 2016, first published online 5 April 2016

Moon and Mars Analog Mission Activities for Mauna Kea 2012

Rover-based 2012 Moon and Mars Analog Mission Activities (MMAMA) scientific investigations were recently completed at Mauna Kea, Hawaii. Scientific investigations, scientific input, and science operations constraints were tested in the context of an existing project and protocols for the field activities designed to help NASA achieve the Vision for Space Exploration. Initial science operations were planned based on a model similar to the operations control of the Mars Exploration Rovers (MER). However, evolution of the operations process occurred as the analog mission progressed. We report here on the preliminary sensor data results, an applicable methodology for developing an optimum science input based on productive engineering and science trades and the science operations approach for an investigation into the valley on the upper slopes of Mauna Kea identified as “Apollo Valley.”