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Mars Science Laboratory Mission and Science Investigation.- Collecting Samples in Gale Crater, Mars An Overview of the Mars Science Laboratory Sample Acquisition, Sample Processing and Handling System.- The Mars Science Laboratory Engineering Cameras.- The ChemCam Instrument Suite on the Mars Science Laboratory (MSL) Rover: Body Unit and Combined System Tests.- The ChemCam Instrument Suite on the Mars Science Laboratory (MSL) Rover: Science Objectives and Mast Unit Description.- Ceramic ChemCam Instrument Suite on the Mars Science Laboratory (MSL) Rover: Science Objectives and Mast Unit Description.- Ceramic ChemCam Calibration Targets on Mars Science Laboratory.- Curiosity's Mars Hand Lens Imager (MAHLI) Investigation.- Calibration of the Mars Science Laboratory Alpha Particle X-ray Spectrometer.- Characterization and Calibration of the CheMin Mineralogical Instrument on Mars Science Laboratory.- The Sample Analysis at Mars Investigation and Instrument Suite.- The Mars Science Laboratory Organic Check Material.- The Radiation Assessment Detector (RAD) Investigation.- Dynamic Albedo of Neutrons (DAN) Experiment Onboard NASA's Mars Science Laboratory.- REMS: The Environmental Sensor Suite for the Mars Science Laboratory Rover.- Selection of the Mars Science Laboratory Landing Site.- Surface Properties of the Mars Science Laboratory Candidate Landing Sites: Characterization from Orbit and Predictions.- Meter-Scale Slopes of Candidate MSL Landing Sites from Point Photoclinometry.- Assessment of Environments for Mars Science Laboratory Entry, Descent, and Surface Operations.- Empirical Estimates of Martian Surface Pressure in Support of the Landing of Mars Science Laboratory.

International audience; A single scoop of the Rocknest aeolian deposit was sieved (2 released from the Rocknest sample and the decomposition of a product of N-methyl-N-(tert-butyldimethylsilyl)-trifluoroacetamide (MTBSTFA), a chemical whose vapors were released from a derivatization cup inside SAM. The best candidate for the oxychlorine compounds in Rocknest is a hydrated calcium perchlorate (Ca(ClO4)2*nH2O), based on the temperature release of O2 that correlates with the release of the chlorinated hydrocarbons measured by SAM, although other chlorine-bearing phases are being considered. Laboratory analog experiments suggest that the reaction of Martian chlorine from perchlorate decomposition with terrestrial organic carbon from MTBSTFA during pyrolysis can explain the presence of three chloromethanes and a chloromethylpropene detected by SAM. Chlorobenzene may be attributed to reactions of Martian chlorine released during pyrolysis with terrestrial benzene or toluene derived from 2,6-diphenylphenylene oxide (Tenax) on the SAM hydrocarbon trap. At this time we do not have definitive evidence to support a nonterrestrial carbon source for these chlorinated hydrocarbons, nor do we exclude the possibility that future SAM analyses will reveal the presence of organic compounds native to the Martian regolith.

International audience; The performances of several commercial chiral capillary columns have been evaluated with the aim of determining the one most suitable for enantiomeric separation in a gas chromatograph onboard a space probe. We compared the GC-MS response of three capillary columns coated with different chiral stationary phases (CSP) using volatile chiral organic molecules which are potential markers of a prebiotic organic chemistry. The three different chiral capillary columns are Chirasil-Val, with an amino acid derivative CSP, ChiralDex-β-PM, with a CSP composed of dissolved permethylated β-cyclodextrins in polysiloxane, and Chirasil-Dex, with a CSP made of modified cyclodextrins chemically bonded to the polysiloxane backbone. Both kinetics and thermodynamics studies have been carried out to evaluate the chiral recognition potential in these different types of columns. The thermodynamic parameters also allow a better understanding of the driving forces affecting the retention and separation of the enantiomers. The Chirasil-Dex-CSP displays the best characteristics for an optimal resolution of the chiral compounds, without preliminary derivatization. This CSP had been chosen to be the only chiral column in the Sample Analysis at Mars (SAM) experiment onboard the current Mars Science Laboratory (MSL) mission, and is also part of the Mars Organic Molecules Analyzer (MOMA) gas chromatograph onboard the next Martian mission ExoMars. The use of this column could also be extended to all space missions aimed at studying chirality in space.

Scheduled to land in August of 2012, the Mars Science Laboratory (MSL) Mission was initiated to explore the habitability of Mars. This includes both modern environments as well as ancient environments recorded by the stratigraphic rock record preserved at the Gale crater landing site. The Curiosity rover has a designed lifetime of at least one Mars year (∼23 months), and drive capability of at least 20 km. Curiosity’s science payload was specifically assembled to assess habitability and includes a gas chromatograph-mass spectrometer and gas analyzer that will search for organic carbon in rocks, regolith fines, and the atmosphere (SAM instrument); an x-ray diffractometer that will determine mineralogical diversity (CheMin instrument); focusable cameras that can image landscapes and rock/regolith textures in natural color (MAHLI, MARDI, and Mastcam instruments); an alpha-particle x-ray spectrometer for in situ determination of rock and soil chemistry (APXS instrument); a laser-induced breakdown spectrometer to remotely sense the chemical composition of rocks and minerals (ChemCam instrument); an active neutron spectrometer designed to search for water in rocks/regolith (DAN instrument); a weather station to measure modern-day environmental variables (REMS instrument); and a sensor designed for continuous monitoring of background solar and cosmic radiation (RAD instrument). The various payload elements will work together to detect and study potential sampling targets with remote and in situ measurements; to acquire samples of rock, soil, and atmosphere and analyze them in onboard analytical instruments; and to observe the environment around the rover. The 155-km diameter Gale crater was chosen as Curiosity’s field site based on several attributes: an interior mountain of ancient flat-lying strata extending almost 5 km above the elevation of the landing site; the lower few hundred meters of the mountain show a progression with relative age from clay-bearing to sulfate-bearing strata, separated by an unconformity from overlying likely anhydrous strata; the landing ellipse is characterized by a mixture of alluvial fan and high thermal inertia/high albedo stratified deposits; and a number of stratigraphically/geomorphically distinct fluvial features. Samples of the crater wall and rim rock, and more recent to currently active surface materials also may be studied. Gale has a well-defined regional context and strong evidence for a progression through multiple potentially habitable environments. These environments are represented by a stratigraphic record of extraordinary extent, and insure preservation of a rich record of the environmental history of early Mars. The interior mountain of Gale Crater has been informally designated at Mount Sharp, in honor of the pioneering planetary scientist Robert Sharp. The major subsystems of the MSL Project consist of a single rover (with science payload), a Multi-Mission Radioisotope Thermoelectric Generator, an Earth-Mars cruise stage, an entry, descent, and landing system, a launch vehicle, and the mission operations and ground data systems. The primary communication path for downlink is relay through the Mars Reconnaissance Orbiter. The primary path for uplink to the rover is Direct-from-Earth. The secondary paths for downlink are Direct-to-Earth and relay through the Mars Odyssey orbiter. Curiosity is a scaled version of the 6-wheel drive, 4-wheel steering, rocker bogie system from the Mars Exploration Rovers (MER) Spirit and Opportunity and the Mars Pathfinder Sojourner. Like Spirit and Opportunity, Curiosity offers three primary modes of navigation: blind-drive, visual odometry, and visual odometry with hazard avoidance. Creation of terrain maps based on HiRISE (High Resolution Imaging Science Experiment) and other remote sensing data were used to conduct simulated driving with Curiosity in these various modes, and allowed selection of the Gale crater landing site which requires climbing the base of a mountain to achieve its primary science goals. The Sample Acquisition, Processing, and Handling (SA/SPaH) subsystem is responsible for the acquisition of rock and soil samples from the Martian surface and the processing of these samples into fine particles that are then distributed to the analytical science instruments. The SA/SPaH subsystem is also responsible for the placement of the two contact instruments (APXS, MAHLI) on rock and soil targets. SA/SPaH consists of a robotic arm and turret-mounted devices on the end of the arm, which include a drill, brush, soil scoop, sample processing device, and the mechanical and electrical interfaces to the two contact science instruments. SA/SPaH also includes drill bit boxes, the organic check material, and an observation tray, which are all mounted on the front of the rover, and inlet cover mechanisms that are placed over the SAM and CheMin solid sample inlet tubes on the rover top deck.

International audience; The Sample Analysis at Mars (SAM) investigation of the Mars Science Laboratory (MSL) addresses the chemical and isotopic composition of the atmosphere and volatiles extracted from solid samples. The SAM investigation is designed to contribute substantially to the mission goal of quantitatively assessing the habitability of Mars as an essential step in the search for past or present life on Mars. SAM is a 40 kg instrument suite located in the interior of MSL's Curiosity rover. The SAM instruments are a quadrupole mass spectrometer, a tunable laser spectrometer, and a 6-column gas chromatograph all coupled through solid and gas processing systems to provide complementary information on the same samples. The SAM suite is able to measure a suite of light isotopes and to analyze volatiles directly from the atmosphere or thermally released from solid samples. In addition to measurements of simple inorganic compounds and noble gases SAM will conduct a sensitive search for organic compounds with either thermal or chemical extraction from sieved samples delivered by the sample processing system on the Curiosity rover's robotic arm.

International audience; The search for complex organic molecules on Mars, including important biomolecules such as amino acids and carboxylic acids will require a chemical extraction and a derivatization step to transform these organic compounds into species that are sufficiently volatile to be detected by gas chromatography mass spectrometry (GCMS). We have developed a "one-pot" extraction and chemical derivatization protocol using N-methyl-N-(tert-butyldimethylsilyl) trifluoroacetamide (MTBSTFA) and dimethylformamide (DMF) for the Sample Analysis at Mars (SAM) experiment instrument suite on NASA's the Mars Science Laboratory (MSL) mission. The temperature and duration of the derivatization reaction, pre-concentration of chemical derivatives, and gas chromatographic separation parameters have been optimized under SAM instrument design constraints. MTBSTFA/DMF extraction and derivatization at 300 °C for several minutes of a variety of terrestrial Mars analogue materials facilitated the detection of amino acids and carboxylic acids in a surface soil sample collected from the Atacama Desert and a carbonate-rich stromatolite sample from Svalbard. However, the rapid reaction of MTBSTFA with water in several analogue materials that contained high abundances of hydrated minerals, and the possible deactivation of derivatized compounds by iron oxides, as detected by XRD/XRF using the CheMin field unit Terra, proved to be highly problematic for the direct extraction of organics using MTBSTFA. The combination of pyrolysis and two different wet-chemical derivatization methods employed by SAM should enable a wide range of organic compounds to be detected by GCMS if present on Mars.

Lasers shine new light on the drying of Mars while reviving the mystery of methane [Also see Reports by Mahaffy et al. and Webster et al. ]

[1] The most comprehensive search for organics in the Martian soil was performed by the Viking Landers. Martian soil was subjected to a thermal volatilization process to vaporize and break organic molecules, and the resultant gases and volatiles were analyzed by gas chromatography-mass spectrometry. Only water at 0.1–1.0 wt% was detected, with traces of chloromethane at 15 ppb, at Viking landing site 1, and water at 0.05–1.0 wt% and carbon dioxide at 50–700 ppm, with traces of dichloromethane at 0.04–40 ppb, at Viking landing site 2. These chlorohydrocarbons were considered to be terrestrial contaminants, although they had not been detected at those levels in the blank runs. Recently, perchlorate was discovered in the Martian Arctic soil by the Phoenix Lander. Here we show that when Mars-like soils from the Atacama Desert containing 32 ± 6 ppm of organic carbon are mixed with 1 wt% magnesium perchlorate and heated, nearly all the organics present are decomposed to water and carbon dioxide, but a small amount is chlorinated, forming 1.6 ppm of chloromethane and 0.02 ppm of dichloromethane at 500°C. A chemical kinetics model was developed to predict the degree of oxidation and chlorination of organics in the Viking oven. Reinterpretation of the Viking results therefore suggests ≤0.1% perchlorate and 1.5–6.5 ppm organic carbon at landing site 1 and ≤0.1% perchlorate and 0.7–2.6 ppm organic carbon at landing site 2. The detection of organics on Mars is important to assess locations for future experiments to detect life itself.

Times Cited: 22 Isotopic studies indicate that natural perchlorate is produced on Earth in arid environments by the oxidation of chlorine species through pathways involving ozone or its photochemical products. With this analogy, we propose that the arid environment on Mars may have given rise to perchlorate through the action of atmospheric oxidants. A variety of hypothetical pathways can be proposed including photochemical reactions, electrostatic discharge, and gas-solid reactions. Because perchlorate-rich deposits in the Atacama desert are closest in abundance to perchlorate measured at NASA's Phoenix Lander site, we made a preliminary study of the means to produce Atacama perchlorate to help shed light on the origin of Martian perchlorate. We investigated gas phase pathways using a 1-D photochemical model. We found that perchlorate can be produced in sufficient quantities to explain the abundance of perchlorate in the Atacama from a proposed gas phase oxidation of chlorine volatiles to perchloric acid. The feasibility of gas phase production for the Atacama provides justification for future investigations of gas phase photochemistry as a possible source for Martian perchlorate. Publisher PDF

Living systems produce more than 90% of Earth's atmospheric methane; the balance is of geochemical origin. On Mars, methane could be a signature of either origin. Using high-dispersion infrared spectrometers at three ground-based telescopes, we measured methane and water vapor simultaneously on Mars over several longitude intervals in northern early and late summer in 2003 and near the vernal equinox in 2006. When present, methane occurred in extended plumes, and the maxima of latitudinal profiles imply that the methane was released from discrete regions. In northern midsummer, the principal plume contained ∼19,000 metric tons of methane, and the estimated source strength (≥0.6 kilogram per second) was comparable to that of the massive hydrocarbon seep at Coal Oil Point in Santa Barbara, California.

The objective of the 2009 Mars Science Laboratory (MSL), which is planned to follow the Mars Exploration Rovers and the Phoenix lander to the surface of Mars, is to explore and assess quantitatively a site on Mars as a potential habitat for present or past life. Specific goals include an assessment of the past or present biological potential of the target environment and a characterization of its geology and geochemistry. Included in the 10 investigations of the MSL rover is the Sample Analysis at Mars (SAM) instrument suite, which is designed to obtain trace organic measurements, measure water and other volatiles, and measure several light isotopes with experiment sequences designed for both atmospheric and solid-phase samples. SAM integrates a gas chromatograph, a mass spectrometer, and a tunable laser spectrometer supported by sample manipulation tools both within and external to the suite. The sub-part-per-billion sensitivity of the suite for trace species, particularly organic molecules, along with a mobile platform that will contain many kilograms of organic materials, presents a considerable challenge due to the potential for terrestrial contamination to mask the signal of martian organics. We describe the effort presently underway to understand and mitigate, wherever possible within the resource constraints of the mission, terrestrial contamination in MSL and SAM measurements.

Geometric optics and matrix methods are used to mathematically model multilaser Herriott cells for tunable laser absorption spectrometers for planetary missions. The Herriott cells presented accommodate several laser sources that follow independent optical paths but probe a single gas cell. Strategically placed output holes located in the far mirrors of the Herriott cells reduce the size of the spectrometers. A four-channel Herriott cell configuration is presented for the specific application as the sample cell of the tunable laser spectrometer instrument selected for the sample analysis at Mars analytical suite on the 2009 Mars Science Laboratory mission.

The “Sample Analysis at Mars” project (SAM) is a multi purpose space experiment devoted to the in situ analysis of the Martian environment. It is designed to run multiple analyses on gas or solid samples, and eventually liquids, and is proposed to be part of the scientific payload of the future NASA Mars Science Laboratory 2009 (MSL 2009). One of its main objectives is to discover traces of a past or present life on the planet. Here is presented the laboratory pilot system for automated analysis of possibly refractory organic matter in Martian soil samples, which corresponds to a part of the Chemical Separation and Processing Laboratory of SAM experiment. It is a one-pot process performing, in a row, extraction, derivatization and transfer of the organic molecules to a gas chromatography–mass spectrometer for analysis. We have shown that such a system is able to detect 10 pmol of refractive material from a 100 mg sample of Atacama desert, which is a good Martian analogue for organics analysis. This pilot can handle and allow the analysis of a wide range of molecules, including carboxylic and amino acids, which are of utmost interest for the goal which is aimed. Further on, such a system is universal, and could be taken as a good start for any future in situ exploratory space mission.

International audience; We report a detection of methane in the martian atmosphere by the Planetary Fourier Spectrometer onboard the Mars Express spacecraft. The global average methane mixing ratio is found to be 10 +/- 5 parts per billion by volume (ppbv). However, the mixing ratio varies between 0 and 30 ppbv over the planet. The source of methane could be either biogenic or nonbiogenic, including past or present subsurface microorganisms, hydrothermal activity, or cometary impacts.

International audience; Observation of Mars shows signs of a past Earth-like climate, and, in that case, there is no objection to the possible development of life, in the underground or at the surface, as in the terrestrial primitive biosphere. Sample analysis at Mars (SAM) is an experiment which may be proposed for atmospheric, ground and underground in situ measurements. One of its goals is to bring direct or indirect information on the possibility for life to have developed on Mars, and to detect traces of past or present biological activity. With this aim, it focuses on the detection of organic molecules: volatile organics are extracted from the sample by simple heating, whereas refractory molecules are made analyzable (i.e. volatile), using derivatization technique or fragmentation by pyrolysis. Gaseous mixtures thus obtained are analyzed by gas chromatography associated to mass spectrometry. Beyond organics, carbonates and other salts are associated to the dense and moist atmosphere necessary to the development of life, and might have formed and accumulated in some places on Mars. They represent another target for SAM. Heating of the samples allows the analysis of structural gases of these minerals (CO2 from carbonates, etc.), enabling to identify them. We also show, in this paper, that it may be possible to discriminate between abiotic minerals, and minerals (shells, etc.) created by living organisms.

GC-MS on the Viking 1976 Mars missions did not detect organic molecules on the Martian surface, even those expected from meteorite bombardment. This result suggested that the Martian regolith might hold a potent oxidant that converts all organic molecules to carbon dioxide rapidly relative to the rate at which they arrive. This conclusion is influencing the design of Mars missions. We reexamine this conclusion in light of what is known about the oxidation of organic compounds generally and the nature of organics likely to come to Mars via meteorite. We conclude that nonvolatile salts of benzenecarboxylic acids, and perhaps oxalic and acetic acid, should be metastable intermediates of meteoritic organics under oxidizing conditions. Salts of these organic acids would have been largely invisible to GC-MS. Experiments show that one of these, benzenehexacarboxylic acid (mellitic acid), is generated by oxidation of organic matter known to come to Mars, is rather stable to further oxidation, and would not have been easily detected by the Viking experiments. Approximately 2 kg of meteorite-derived mellitic acid may have been generated per m 2 of Martian surface over 3 billion years. How much remains depends on decomposition rates under Martian conditions. As available data do not require that the surface of Mars be very strongly oxidizing, some organic molecules might be found near the surface of Mars, perhaps in amounts sufficient to be a resource. Missions should seek these and recognize that these complicate the search for organics from entirely hypothetical Martian life.

[Curiosity Special Section Index][1] The 6 August 2012 arrival of the curiosity rover on the surface of Mars delivered the most technically advanced geochemistry laboratory ever sent to the surface of another planet. Its 10 instruments ( 1 )[*][2] were commissioned for operations and were tested on a diverse set of materials, including rocks, soils, and the atmosphere, during the first 100 martian days (sols) of the mission. The five articles presented in full in the online edition of Science ([www.sciencemag.org/extra/curiosity][3]), with abstracts in print (pp. 1476–1477), describe the mission's initial results, in which Curiosity's full laboratory capability was used. Curiosity was sent to explore a site located in Gale crater, where a broad diversity of materials was observed from orbit. Materials representing interactions with aqueous environments were targeted for study because of the emphasis on understanding habitable environments. In addition, the mission's science objectives also include characterizing the geologic diversity of the landing site at all scales, including loose surface materials such as impact ejecta, soils, and windblown accumulations of fine sediments. In certain cases, such characterization may even provide constraints on the evolution of the planet as a whole. Two notable points along Curiosity's initial 500-m traverse included Jake_M, a loose rock sitting on the plains, and Rocknest, an accumulation of windblown sand, silt, and dust that formed in the lee of some rocky outcrops. Sparse outcrops of lithified fluvial conglomerate were also encountered ( 2 ). ![Figure][4] Curiosity used its scoop to collect two samples of a small aeolian deposit. The deposit's upper surface is armored by sand grains 0.5 to 1.5 mm in size. These coarse grains are coated with fine dust, giving the deposit an overall light brownish red color. Beneath the coarse sand crust is finer sand, dark brown in color. This Mars Hand Lens Imager image was acquired on sol 84. CREDIT: NASA As described by Stolper et al. , Jake\_M was encountered ∼282 m away from the landing site and is a dark, macroscopically homogeneous igneous rock representing a previously unknown martian magma type. In contrast to the relatively unfractionated Fe-rich and Al-poor tholeiitic basalts typical of martian igneous rocks, it is highly alkaline and fractionated. No other known martian rock is as compositionally similar to terrestrial igneous rocks; Jake\_M compares very closely with an uncommon terrestrial rock type known as a mugearite, typically found on ocean islands and in rift zones. It probably originates from magmas generated by low degrees of partial melting at high pressure of possibly water-rich, chemically altered martian mantle that is different from the sources of other known martian basalts. Over the first 100 sols of the mission, the ChemCam instrument returned >10,000 laser-induced breakdown spectra, helping to characterize surface material diversity. ChemCam's laser acts effectively as a microprobe, distinguishing between fine soil grains and coarser ∼1-mm grains. Based on these data, Meslin et al. report that the coarse soil fraction contains felsic (Si- and Al-rich) grains, mimicking the composition of larger felsic rock fragments found during the traverse and showing that these larger components probably break apart to form part of the soil. In contrast, the fine-grained soil component is mafic, similar to soils observed by the Pathfinder and Mars Exploration Rover missions. Curiosity scooped, processed, and analyzed a small deposit of windblown sand/silt/dust at Rocknest that has similar morphology and bulk elemental composition to other aeolian deposits studied at other Mars landing sites. Based solely on analysis of CheMin x-ray diffraction (XRD) data from Mars, calibrated with terrestrial standards, Bish et al. estimate the Rocknest deposit to be composed of ∼71% crystalline material of basaltic origin, in addition to ∼29% x-ray–amorphous materials. In an independent approach, Blake et al. used Alpha Particle X-ray Spectrometer data to constrain the bulk composition of the deposit and XRD data and phase stoichiometry to constrain the chemistry of the crystalline component, with the difference being attributed to the amorphous component, resulting in estimates of ∼55% crystalline material of basaltic origin and ∼45% x-ray–amorphous materials. The amorphous component may contain nanophase iron oxide similar to what was observed by earlier rovers. The similarity between basaltic soils observed at Rocknest and other Mars sites implies either global-scale mixing of basaltic material or similar regional-scale basaltic source material or some combination of both. No hydrated phases were detected. However, as shown by Leshin et al. , pyrolysis of Rocknest fines using the Sample Analysis at Mars (SAM) instrument suite revealed volatile species, probably in the amorphous component, including H2O, SO2, CO2, and O2, in order of decreasing abundance. ChemCam measurements of these materials also revealed the presence of H. It is likely that H2O is contained in the amorphous component and CO2 was liberated via the decomposition of Fe/Mg carbonates present below the XRD detection limit of 1 to 2%. Isotopic data from SAM indicate that this H2O, and possibly the CO2, were derived from the atmosphere. SAM analysis also revealed oxychloride compounds similar to those found by earlier missions, suggesting that their accumulation reflects global planetary processes. The evolution of CO2 during pyrolysis and the observation of simple chlorohydrocarbons during SAM gas chromatograph mass spectrometer analyses could be consistent with organic carbon derived from a terrestrial instrument background source, or a martian source, either exogenous or indigenous. [Soil Diversity and Hydration as Observed by ChemCam at Gale Crater, Mars][5] [X-ray Diffraction Results from Mars Science Laboratory: Mineralogy of Rocknest at Gale Crater][6] [Volatile, Isotope, and Organic Analysis of Martian Fines with the Mars Curiosity Rover][7] [The Petrochemistry of Jake_M: A Martian Mugearite][8] [Curiosity at Gale Crater, Mars: Characterization and Analysis of the Rocknest Sand Shadow][9] Additional Curiosity research, news, and multimedia can be found at [www.sciencemag.org/extra/curiosity][10] [1]: http://www.sciencemag.org/site/extra/curiosity/index.xhtml [2]: #fn-1 [3]: http://www.sciencemag.org/extra/curiosity [4]: pending:yes [5]: http://www.sciencemag.org/content/341/6153/1238670.abstract [6]: http://www.sciencemag.org/content/341/6153/1238932.abstract [7]: http://www.sciencemag.org/content/341/6153/1238937.abstract [8]: http://www.sciencemag.org/content/341/6153/1239463.abstract [9]: http://www.sciencemag.org/content/341/6153/1239505.abstract [10]: http://www.sciencemag.org/extra/curiosity/index.xhtml

Carbon delivered to the Earth by interplanetary dust particles may have been an important source of pre-biotic organic matter (Anders, 1989). Interplanetary dust is shown to deliver an order-of-magnitude higher surface concentration of carbon onto Mars than onto Earth, suggesting interplanetary dust may be an important source of carbon on Mars as well.

A total of four Martian samples, one surface and one subsurface sample at each of the two Viking landing sites, Chryse Planitia and Utopia Planitia, have been analyzed for organic compounds by a gas chromatograph-mass spectrometer. In none of these experiments could organic material of Martian origin be detected at detection limits generally of the order of parts per billion and for a few substances closer to parts per million. The evolution of water and carbon dioxide, but not of other inorganic gases, was observed upon heating the sample to temperatures of up to 500 C. The absence of organic compounds seems to preclude their production on the planet at rates that exceed the rate of their destruction. It also makes it unlikely that living systems that behave in a manner similar to terrestrial biota exist, at least at the two Viking landing sites.

A principal goal of the Mars Science Laboratory (MSL) rover Curiosity is to identify and characterize past habitable environments on Mars. Determination of the mineralogical and chemical composition of Martian rocks and soils constrains their formation and alteration pathways, providing information on climate and habitability through time. The CheMin X-ray diffraction (XRD) and X-ray fluorescence (XRF) instrument on MSL will return accurate mineralogical identifications and quantitative phase abundances for scooped soil samples and drilled rock powders collected at Gale Crater during Curiosity’s 1-Marsyear nominal mission. The instrument has a Co X-ray source and a cooled charge-coupled device (CCD) detector arranged in transmission geometry with the sample. CheMin’s angular range of 5° to 50° 2θ with < 0.35° 2θ resolution is sufficient to identify and quantify virtually all minerals. CheMin’s XRF requirement was descoped for technical and budgetary reasons. However, X-ray energy discrimination is still required to separate Co Kα from Co Kβ and Fe Kα photons. The X-ray energy-dispersive histograms (EDH) returned along with XRD for instrument evaluation should be useful in identifying elements Z >13 that are contained in the sample. The CheMin XRD is equipped with internal chemical and mineralogical standards and 27 reusable sample cells with either Mylar® or Kapton® windows to accommodate acidic-to-basic environmental conditions. The CheMin flight model (FM) instrument will be calibrated utilizing analyses of common samples against a demonstrationmodel (DM) instrument and CheMin-like laboratory instruments. The samples include phyllosilicate and sulfate minerals that are expected at Gale crater on the basis of remote sensing observations.

Two surface samples collected from the Chryse Planitia region of Mars were heated to temperatures up to 500 degrees C, and the volatiles that they evolved were analyzed with a gas chromatograph-mass spectrometer. Only water and carbon dioxide were detected. This implies that organic compounds have not accumulated to the extent that individual components could be detected at levels of a few parts in 10(9) by weight in our samples. Proposed mechanisms for the accumulation and destruction of organic compounds are discussed in the light of this limit.