ALBERT

Description: Mineral identification is a critical component of Mars Astrobiological missions. Chemical or elemental data alone are not definitive because a single elemental or chemical composition or even a single bonding type can represent a range of substances or mineral assemblages. Minerals are defined as unique structural and compositional phases that occur naturally. There are about 15,000 minerals that have been described on Earth, all uniquely identifiable via diffraction methods. There are likely many minerals yet undiscovered on Earth, and likewise on Mars. If an unknown phase is identified on Mars, it can be fully characterized by structural (X-ray Diffraction, XRD) and elemental analysis (X-ray Fluorescence, XRF) without recourse to other data because XRD relies on the principles of atomic arrangement for its determinations. XRD is the principal means of identification and characterization of minerals on Earth.

Description: Mineralogical analysis is a critical component of planetary surface exploration. Chemical data alone leave serious gaps in our understanding of the surfaces of planets where complex minerals may form in combination with H, S, and halogens. On such planets (e.g., Mars) a single chemical composition may represent a range of mineral assemblages. For example, Viking chemical analyses of excavated duricrust indicate that Mg and S are correlated and ~10% MgSO4 (anhydrous weight) is a likely cementing agent. Pathfinder chemical data support a similar abundance of MgSO4 in the most altered materials. However, there are many possible Mg-sulfates with widely varying hydration states (including dehydrated and 1-, 2-, 3-, 4-, 5-, 6-, and 7-hydrates). In addition, other sulfate minerals such as gypsum (CaSO4 .2H2O) and other salts containing Cl may also exist. X-ray diffraction (XRD) has the ability to decipher mixtures of these phases that would be difficult, if not impossible to unravel using only chemical or spectral data.

Description: The Mars Science Laboratory rover, Curiosity, landed at Gale crater in August 2012 and has been investigating a sequence of dominantly fluviolacustrine sediments deposited 3.6-3.2 billion years ago. Curiosity collects quantitative mineralogical data with the CheMin XRD/XRF instrument and quantitative chemical data with the APXS and ChemCam instruments. These datasets show stratigraphic mineralogical and geochemical variability that suggest a complex aqueous history. The Murray Formation, primarily composed of fine-laminated mudstone, has been studied in detail since the arrival at the Pahrump Hills in September 2014. CheMin data from four samples show variable amounts of iron oxides, phyllosilicates, sulfates, amorphous and crystalline silica, and mafic silicate minerals. Geochemical data throughout the section show that there is significant variability in Zn, Ni, and Mn concentrations. Mineralogical and geochemical trends with stratigraphy suggest one of possibly several aqueous episodes involved alteration in an open system under acidic pH, though other working hypotheses may explain these and other trends. Data from the Murray Formation contrast with those collected from the Sheepbed mudstone located approximately 60 meters below the base of the Murray Formation, which showed evidence for diagenesis in a closed system at circumneutral pH. Ca-sulfates filled late-stage veins in both mudstones.

Description: The CheMin X-ray diffraction (XRD) instrument onboard the Mars Science Laboratory rover Curiosity in Gale Crater, Mars, discovered smectite in drill fines of the Sheepbed mudstone at Yellowknife Bay (YNB). The mudstone has a basaltic composition, and the XRD powder diffraction pattern shows smectite 02l diffraction bands peaking at 4.59 A for targets John Klein and Cumberland, consistent with tri-octahedral smectites (saponite). From thermal analysis, the saponite abundance is ~20 wt. %. Among terrestrial analogues we have studied, ferrian saponite from Griffith Park (Los Angeles, CA) gives the best match to the position of the 02l diffraction band of YNB saponites. Here we describe iron-rich saponites from a terrestrial perspective, with a focus on Griffith saponite, and discuss their implications for the mineralogy of Sheepbed saponite and its formation pathways. Iron-rich saponite: Iron-rich saponite on the Earth is recognized as a low-temperature (〈100 C), authigenic alteration product of basalt [e.g., 4-16]. In the discussion that follows, we reference the position of the 02l band because it is a measure of the unit cell 'b' dimension of the octahedral layer and thus the cations (including Fe redox state) in the octahedral layer. Ordinarily, the 06l band near 1.5 A is used to determine the 'b' dimension of smectite, but this band is not accessible with MSL CheMin instrument. For reference, a ferrosaponite (i.e., Fe2+ saponite) studied by [15] has a 02l spacing of 4.72 A and Fe3+/Fe = 0.27 [15]. Samples of terrestrial ferrosaponite, however, are reported to oxidize on the timescale of days when removed from their natural environment and not protected from oxidation. The Griffith saponite is Mg-rich ferrian saponite, and sample AMNH 89172 has an 02l spacing of 4.59 A (same as the Sheepbed saponites) and Fe3+/Fe = 0.64 [3]. This similarity suggests that Sheepbed saponites are ferrian (incompletely oxidized ferrosaponite). More oxidized Griffith saponites (Fe3+/Fe 〉 0.90) have somewhat smaller 02l d-spacings and also show Mossbauer evidence for an XRD amorphous Fe-bearing phase (e.g., ferrihydrite, hisingerite, superparamagnetic ferric oxides, etc.). The Griffith saponite occurs as vesicle fills, as replacements of olivine, and as replacements of mesostasis (basaltic glass). Similar occurrence modes are reported elsewhere. Hisingerite has been proposed by [13] as the alteration product of ferrian saponite whose precursor by oxidation was ferrosaponite.

Description: The Mars Science Laboratory Curiosity rover landed in Gale crater in August 2012 to characterize modern and ancient surface environments. Curiosity executed a two-phase campaign to study the morphology, activity, physical properties, and chemical and mineralogical composition of the Bagnold Dune Field, an active eolian dune field on the lower slopes of Aeolis Mons (Mount Sharp). Detectable aspects of dune sand mineralogy have been examined from orbit with the visible/short-wave infrared spectrometer CRISMand the thermal-infrared spectrometers THEMIS and TES. CRISM data demonstrate variations in plagioclase, pyroxene, and olivine abundances across the dune field. Curiosity analyzed sediments from two locations in the dune field to evaluate the causes of the mineralogical differences observed from orbit. The Gobabeb sample was collected from Namib Dune, a barchanoidal dune on the upwind margin of the dune field, and the Ogunquit Beach sample was collected from the Mount Desert Island sand patch located downwind from Namib. These samples were sieved to 〈150 m and delivered to the CheMin X-ray diffraction instrument for quantitative mineralogical analysis. CRISM-derived mineralogy of the Namib Dune and Mount Desert Island and CheMin-derived mineralogy of the Gobabeb and Ogunquit Beach samples can be used in a value-added manner to interpret grain segregation at the bedform to dune-field scale and evaluate contributions from local sediment sources. Models of CRISM data demonstrate that Mount Desert Island is more enriched in olivine and less enriched in plagioclase than Namib dune, suggesting that fine-grained mafic sediments are preferentially mobilized downwind. Curiosity data indicate olivine also forms a coarse lag on the lee sides of barchanoidal dunes. Minor abundances of hematite, quartz, and anhydrite and small differences in the crystal chemistry of plagioclase and pyroxene derived from CheMin data suggest that sediments from the underlying lacustrine rocks also contribute to the Bagnold sands.

Description: Scientific ground-truth measurements for near-term Mars missions, such as the 2009 Mars Science Laboratory (MSL) mission, are essential for validating current in situ flight instrumentation and for the development of advanced instrumentation technologies for life-detection missions over the next decade. The NASA Astrobiology Institute (NAI) has recently funded a consortium of researchers called the Astrobiology Sample Analysis Program (ASAP) to analyze an identical set of homogenized martian analog materials in a "round-robin" style using both state-of-the-art laboratory techniques as well as in-situ flight instrumentation including the SAM gas chromatograph mass spectrometer and CHEMIN X-ray diffraction/fluorescence instruments on MSL and the Urey and MOMA organic analyzer instruments under development for the 2013 ExoMars missions. The analog samples studied included an Atacama Desert soil from Chile, the Murchison meteorite, a gypsum sample from the 2007 AMASE Mars analog site, jarosite from Panoche Valley, CA, a hydrothermal sample from Rio Tinto, Spain, and a "blind" sample collected during the 2007 MSL slow-motion field test in New Mexico. Each sample was distributed to the team for analysis to: (1) determine the nature and inventory of organic compounds, (2) measure the bulk carbon and nitrogen isotopic composition, (3) investigate elemental abundances, mineralogy and matrix, and (4) search for biological activity. The experimental results obtained from the ASAP Mars analog research consortium will be used to build a framework for understanding the biogeochemistry of martian analogs, help calibrate current spaceflight instrumentation, and enhance the scientific return from upcoming missions.

Description: This report describes the facility and experimental methods at the Goddard Space Flight Center Optics Branch for the measurement of the surface figure of cryogenically-cooled spherical mirrors using standard phase-shifting interferometry, with a standard uncertainty below 2nm rms. Two developmental silicon carbide mirrors were tested: both were spheres with radius of curvature of 600 mm, and clear apertures of 150 mm. The mirrors were cooled within a cryostat, and the surface figure error measured through a fused-silica window. The GSFC team developed methods to measure the in-situ SFE at 20 K with a combined standard uncertainty below 2 nm rms and the change in SFE with temperature (the cryochange) with a combined standard uncertainty of 0.25 -- 0.75 nm rms. This paper will present the measurement facility, methods, and uncertainty analysis.

Description: Basalts and xenoliths from Spitsbergen (Norway) contain carbonate globules nearly identical to those in ALH84001. The Spitsbergen globules formed from hydrothermal waters by analogy, so did those in ALH84001. Additional information is contained in the original extended abstract.

Description: A principal objective of Mars exploration is the search for evidence of past life which may have existed during an earlier clement period of Mars history. We would like to investigate the history of surface water activity (which is a requirement for all known forms of life) by identifying and documenting the distribution of minerals which require water for their formation or distribution. A knowledge of the mineralogy of the present Martian surface would help to identify areas which, due to the early activity of water, might have harbored ancient life. It would be desirable to establish the presence and characterize the distribution of hydrated minerals such as clays, and of minerals which are primarily of sedimentary origin such as carbonates, silica and evaporites. Mineralogy, which is more critical to exobiological exploration than is simple chemical analysis (absent the detection of organics), will remain unknown or will at best be imprecisely constrained unless a technique sensitive to mineral structure such as powder X-ray diffraction (XRD) is employed. Additional information is contained in the original extended abstract.

Description: The legacy of planetary X-ray Diffraction (XRD) and X-ray Fluorescence (XRF) began in 1960 when W. Parish proposed an XRD instrument for deployment on the moon. The instrument was built and flight qualified, but the Lunar XRD program was cancelled shortly before the first human landing in 1969. XRF chemical data have been collected in situ by surface landers on Mars (Viking 1 & 2, Pathfinder) and Venus (Venera 13 & 14). These highly successful experiments provide critical constraints on our current understanding of surface processes and planetary evolution. However, the mineralogy, which is more critical to planetary surface science than simple chemical analysis, will remain unknown or will at best be imprecisely constrained until X-ray diffraction (XRD) data are collected. Recent progress in X-ray detector technology allows the consideration of simultaneous XRD (mineralogic analysis) and high-precision XRF (elemental analysis) in systems miniaturized to the point where they can be mounted on fixed landers or small robotic rovers. There is a variety of potential targets for XRD/XRF equipped landers within the solar system, the most compelling of which are the poles of the moon, the southern highlands of Mars and Europa.