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NASA NTRS2015

Martian Chlorobenzene Identified by Curiosity in Yellowknife Bay: Evidence for the Preservation of Organics in a Mudstone on Mars

The Sample Analysis at Mars (SAM) instrument on the Curiosity rover is designed to determine the inventory of organic and inorganic volatiles thermally evolved from solid samples using a combination of evolved gas analysis (EGA), gas chromatography mass spectrometry (GCMS), and tunable laser spectroscopy. The first sample analyzed by SAM at the Rocknest (RN) aeolian deposit revealed chlorohydrocarbons derived primarily from reactions between a martian oxychlorine phase (e.g. perchlorate) and terrestrial carbon from N-methyl-N-(tert-butyldimethylsilyl) trifluoroacetamide (MTBSTFA) vapor present in the SAM instrument background. No conclusive evidence for martian chlorohydrocarbons in the RN sand was found. After RN, Curiosity traveled to Yellowknife Bay and drilled two holes separated by 2.75 m designated John Klein (JK) and Cumberland (CB). Analyses of JK and CB by both SAM and the CheMin x-ray diffraction instrument revealed a mudstone (called Sheepbed) consisting of approx.20 wt% smectite clays, which on Earth are known to aid the concentration and preservation of organic matter. Last year at LPSC we reported elevated abundances of chlorobenzene (CBZ) and a more diverse suite of chlorinated hydrocarbons including dichloroalkanes in CB compared to RN, suggesting that martian or meteoritic organic compounds may be preserved in the mudstone. Here we present SAM data from additional analyses of the CB sample and of Confidence Hills (CH), another drill sample collected at the base of Mt. Sharp. This new SAM data along with supporting laboratory analog experiments indicate that most of the chlorobenzene detected in CB is derived from martian organic matter preserved in the mudstone.

Glavin, D.↗

NASA NTRS2015

Martian Chlorobenzene Identified by Curiosity in Yellowknife Bay: Evidence for the Preservation of Organics in a Mudstone on Mars

Curiosity in Yellowknife↗

NASA NTRSDate not supplied

The first 300 sols of the SHERLOC investigation on the Mars 2020 rover

The Mars2020 mission is NASA’s latest flagship mission to Mars. The spacecraft launched in July 2020, and landed in Jezero crater on February 18, 2021 at the Octavia Butler Landing site. The rocks and sediments of Jezero crater have been argued to have preserved records of past, potentially habitable environments. The mission is characterizing the field site by analyzing chemistry, looking for organics and searching for potential biosignatures. The Scanning Habitable Environments with Ra-man and Luminescence for Organics and Chemicals (SHERLOC) is a robotic arm mounted instrument. SHERLOC combines imaging with UV resonance Raman and native deep UV fluorescence spectroscopy to identify potential biosignatures and understand the aqueous history of the Jezero Region. WATSON (Wide Angle Topographic Sensor for Operations and eNgineering), a refight of the Mars Hand Lens Imager (MAHLI) on the Curiosity rover is capable of color imaging over a wide range of resolutions (from infinity to 13.1 micron/pixel) and is used for both science and engineering. A second imager, the Autofocusing Con-textual Imager (ACI), produces gray scale images at 10.1 micron/pixel resolution at a 48 mm range.

A. E. Murphy↗

NASA NTRSDate not supplied

Constraining the Hydration of X-Ray Amorphous and Clay Mineral Phases in Gale Crater, Mars

Clay minerals and salts in the Gale crater stratigraphy investigated by the Mars Science Laboratory (MSL) Curiosity rover preserve information about sediment sources, depositional environment, and post-depositional alteration history. The compositions of amorphous components in samples have bearing on the redox potential, pH, and chemistry of alteration fluids, and on the heterogeneity of these conditions. Interlayer clay hydration in present-day Gale crater could be an indication of high water/rock ratios of late-stage fluid alteration events, which increases the potential habitability of these post-depositional environments. The MSL Dynamic Albedo of Neutrons instrument (DAN) measures bulk hydration and here we attempt to determine the hydration states of both clay minerals and amorphous components throughout the Curiosity traverse to constrain the abundance of individual amorphous phases and determine if clay interlayer water is present today. These implications are also more broadly applicable to similar sedimentary successions outside Gale crater. In this study, we compare hydration results from DAN to mineralogical results from the MSL Chemistry and Mineralogy instrument (CheMin) for 16 different fluvio-lacustrine sample locations. These samples typically contain one or more hydrated crystalline phases, a hydrated X-ray amorphous fraction composed of multiple amorphous phases, and one or more clay mineral phases which CheMin has consistently measured as collapsed (i.e., no interlayer water). However, Gale samples are known to dehydrate during sample acquisition and handling, and because DAN measures hydration to a depth of tens of cm, we can test for the presence of clay interlayer water in situ by comparing DAN bulk hydration to CheMin mineralogy. We can also constrain the hydration of the samples’ amorphous fractions, and with geochemical data from the ChemCam and APXS instruments, this will allow us to better define the phases which compose this fraction.

S Czarnecki↗

NASA NTRSDate not supplied

On the Hunt for Detectable Biosignatures in Jezero Crater: What to Look for and Where

Introduction: The Perseverance rover, which is currently exploring Jezero crater on Mars, is equipped with seven instruments that allow for observation of textures, minerals, color, structure, and chemistry of rocks and sediments in order to search for signs of ancient life, understand the geologic history of the crater, and identify candidates for sample return (Farley et al. 2020). The first of these aims includes the direct detection of potential biosignatures, including textures, organic molecules, minerals, and elemental chemistries that are of biogenic origin (Mustard et al. 2013). The presence of these biosignatures will be constrained by the habitability of the local region, the preservation potential of the host rocks, and the sensitivity of the instrument suite, and their biogenicity will be investigated after return to Earth as part of the Mars Sample Return campaign. Here, we examine key targets on the three planned campaigns, potential biosignatures that may be present, and the capabilities of key rover instruments. High Potential Biosignature Sites in Jezero: To date, measurements have been made on multiple sites that both contain minerals known in terrestrial settings to preserve biosignatures and likely were habitable settings (Williford et al. 2021). Two examples include the fine-grained rocks at the base of the delta fan and the NW inner margin of the crater. Fine-grained Rocks at Base of Delta Fan. Fine-grained, clay-bearing rocks may have been deposited as muddy lake sediments that could have hosted life and preserved biosignatures settling out of the water column. The report of organic molecules by the Curiosity rover in the Sheepbed mudstone and Murray formation has highlighted this site in particular. Potential biosignatures in mudstones, especially those rich in silica (McMahon et al. 2018), microbialites and complex organics. NW Inner Margin of Crater. This unit, located along the inner margin of the crater, contains strong carbonate signatures and may have been the littoral zone of a lake (Horgan et al. 2020). The potential biosignatures here include microfossils, microbialites, biominerals, and complex organics. Detectability of Biosignatures by the Mars 2020 Instrument Suite: The Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) instrument comprises a Deep UV spectrometer, context imager, and color camera to generate spatially resolved chemical maps (Bhartia et al. 2020). It is sensitive to trace organics as well as a range of minerals and can detect native fluorescence from aromatic organics; the WATSON and ACI cameras can be used to observe morphologies such as stromatolitic laminations or filaments ranging from the tens of micron to millimeter scale. SHERLOC can detect organics that may be present in either of the high potential biosignature targets, as well as detect carbonates in the latter. However, the presence of high amounts of iron, such as in iron-rich clays, would cause attenuation of spectral response through UV absorption. The Planetary Instrument for X-ray Lithochemistry (PIXL) comprises an X-ray fluorescence spectrometer and camera that can scan rock surfaces to generate elemental maps (Allwood et al. 2020). PIXL can detect chemical biosignatures such as spatial variations of elemental abundances that may have resulted from biological activity. PIXL would be particularly useful in detecting fine textures and elemental chemistries in either high potential biosignature target, but cannot directly detect minerals such as carbonate. The SuperCam instrument performs three types of spectroscopy, color imaging, and acoustic recording to remotely examine elemental composition, minerals, organics, and textures (Maurice et al. 2021). Using laser induced breakdown spectroscopy and time resolved luminescence spectroscopy, SuperCam can detect major elemental building blocks of organics (i.e., C, H, N, O, P, S) and conjugated organic structures, respectively, which may be found in either site. While in other contexts, luminescence is a useful tool for biosignature identification, luminescence generated by the 532 nm laser may obscure the Raman signal. Conclusion: The three instruments discussed can be used collaboratively to establish the presence of potential biosignatures in samples. These high-priority samples may then be returned to Earth for detailed laboratory analysis.

S. Sharma↗

NASA NTRS2013

Relay Support for the Mars Science Laboratory Mission

The Mars Science Laboratory (MSL) mission landed the Curiosity Rover on the surface of Mars on August 6, 2012, beginning a one-Martian-year primary science mission. An international network of Mars relay orbiters, including NASA's 2001 Mars Odyssey Orbiter (ODY) and Mars Reconnaissance Orbiter (MRO), and ESA's Mars Express Orbiter (MEX), were positioned to provide critical event coverage of MSL's Entry, Descent, and Landing (EDL). The EDL communication plan took advantage of unique and complementary capabilities of each orbiter to provide robust information capture during this critical event while also providing low-latency information during the landing. Once on the surface, ODY and MRO have provided effectively all of Curiosity's data return from the Martian surface. The link from Curiosity to MRO incorporates a number of new features enabled by the Electra and Electra-Lite software-defined radios on MRO and Curiosity, respectively. Specifically, the Curiosity-MRO link has for the first time on Mars relay links utilized frequency-agile operations, data rates up to 2.048 Mb/s, suppressed carrier modulation, and a new Adaptive Data Rate algorithm in which the return link data rate is optimally varied throughout the relay pass based on the actual observed link channel characteristics. In addition to the baseline surface relay support by ODY and MRO, the MEX relay service has been verified in several successful surface relay passes, and MEX now stands ready to provide backup relay support should NASA's orbiters become unavailable for some period of time.

Telecommunications↗

NASA NTRS2020

Neighbors on the Red Planet: Mars Science Laboratory Relay Coordination Post InSight Arrival

The Mars Science Laboratory (MSL) strategic communications planning toolset selects orbiter relay opportunities that the rover will use for transmitting data back to Earth. The toolset was extensively reworked in preparation for the Interior Exploration using Seismic Investigations, Geodesy and Heat Transport's (InSight) arrival at Mars in November 2018 and the regular use of Mars Atmosphere and Volatile Evolution (MAVEN) and Trace Gas Orbiter (TGO) orbiters as relay assets in addition to Mars Reconnaissance Orbiter (MRO) and 2001 Mars Odyssey (ODY). Overflight selection criteria was automated in the new toolset to take into account overflight deconfliction and down-selection as well as tactical timeline planning impacts and total data return. This was done while remaining flexible and configurable for changing mission priorities. As the Curiosity rover ages, the MSL planning team must overcome issues such as reduced budgets, memory bank anomalies, and reduced power availability. These are some examples of factors that affect the strategic communications planning toolset. In addition to adapting to evolving internal mission needs, the toolset must also be flexible to changes in the relay planning interface with other landers. The concept of shared relay or “split passes” was introduced when InSight began operating on Mars just 600 kilometers away and at the same longitude as MSL. This proximity meant that orbiters could now communicate with two landers during the same relay session. Over time, this new operational use-case became common practice as InSight and MSL settled into relay planning negotiations. Today, many TGO relay sessions are shared between MSL and InSight. As more orbiters pursue integrating this capability into nominal relay operations, and more landers arrive on Mars, the strategic communications process and toolsets increases in complexity. Development of a single tool that schedules relay sessions for all orbiters and landers simultaneously may become necessary as the number of Martian spacecraft increases. Examples of how toolset selection criteria and capabilities have helped or hindered MSL planning will be presented. Ongoing improvements to MSL toolsets and processes, as well as to shared relay tools such as Mars Relay Operations Service (MaROS) and General Telecom Predictor (GTP) are also discussed in this paper. Examples of how toolset selection criteria and capabilities have helped or hindered MSL planning will be presented. Ongoing improvements to MSL toolsets and processes, as well as to shared relay tools such as Mars Relay Operations Service (MaROS) and General Telecom Predictor (GTP) are also discussed in this paper.

Vandermey, Nancy↗

NASA NTRS2013

Potential Applications for Radioisotope Power Systems in Support of Human Exploration Missions

Radioisotope power systems (RPS) for space applications have powered over 27 U.S. space systems, starting with Transit 4A and 4B in 1961, and more recently with the successful landing of the Mars Science Laboratory rover Curiosity in August 2012. RPS enable missions with destinations far from the Sun with faint solar flux, on planetary surfaces with dense or dusty atmospheres, and at places with long eclipse periods where solar array sizes and energy storage mass become impractical. RPS could also provide an enabling capability in support of human exploration activities. It is envisioned that with the higher power needs of most human mission concepts, a high efficiency thermal-to-electric technology would be required such as the Advanced Stirling Radioisotope generator (ASRG). The ASRG should be capable of a four-fold improvement in efficiency over traditional thermoelectric RPS. While it may be impractical to use RPS as a main power source, many other applications could be considered, such as crewed pressurized rovers, in-situ resource production of propellants, back-up habitat power, drilling, any mobile or remote activity from the main base habitat, etc. This paper will identify potential applications and provide concepts that could be a practical extension of the current ASRG design in providing for robust and flexible use of RPS on human exploration missions.

Cataldo, Robert L.↗

NASA NTRS2015

Fluvial to Lacustrine Facies Transitions in Gale Crater, Mars

NASA's Curiosity rover has documented predominantly fluvial sedimentary rocks along its path from the landing site to the toe of the Peace Vallis alluvial fan (0.5 km to the east) and then along its 8 km traverse across Aeolis Palus to the base of Aeolis Mons (Mount Sharp). Lacustrine facies have been identified at the toe of the Peace Vallis fan and in the lowermost geological unit exposed on Aeolis Mons. These two depositional systems provide end members for martian fluvial/alluvial-lacustrine facies models. The Peace Vallis system consisted of an 80 square kilometers alluvial fan with decimeter-thick, laterally continuous fluvial sandstones with few sedimentary structures. The thin lacustrine unit associated with the fan is interpreted as deposited in a small lake associated with fan runoff. In contrast, fluvial facies exposed over most of Curiosity's traverse to Aeolis Mons consist of sandstones with common dune-scale cross stratification (including trough cross stratification), interbedded conglomerates, and rare paleochannels. Along the southwest portion of the traverse, sandstone facies include south-dipping meter-scale clinoforms that are interbedded with finer-grained mudstone facies, interpreted as lacustrine. Sedimentary structures in these deposits are consistent with deltaic deposits. Deltaic deposition is also suggested by the scale of fluvial to lacustrine facies transitions, which occur over greater than 100 m laterally and greater than 10 m vertically. The large scale of the transitions and the predicted thickness of lacustrine deposits based on orbital mapping require deposition in a substantial river-lake system over an extended interval of time. Thus, the lowermost, and oldest, sedimentary rocks in Gale Crater suggest the presence of substantial fluvial flow into a long-lived lake. In contrast, the Peace Vallis alluvial fan onlaps these older deposits and overlies a major unconformity. It is one of the youngest deposits in the crater, and requires only short-lived, transient flows.

Sumner, Dawn Y.↗

NASA NTRS2011

Mars Science Laboratory Flight Software Internal Testing

The Mars Science Laboratory (MSL) team is sending the rover, Curiosity, to Mars, and therefore is physically and technically complex. During my stay, I have assisted the MSL Flight Software (FSW) team in implementing functional test scripts to ensure that the FSW performs to the best of its abilities. There are a large number of FSW requirements that have been written up for implementation; however I have only been assigned a few sections of these requirements. There are many stages within testing; one of the early stages is FSW Internal Testing (FIT). The FIT team can accomplish this with simulation software and the MSL Test Automation Kit (MTAK). MTAK has the ability to integrate with the Software Simulation Equipment (SSE) and the Mission Processing and Control System (MPCS) software which makes it a powerful tool within the MSL FSW development process. The MSL team must ensure that the rover accomplishes all stages of the mission successfully. Due to the natural complexity of this project there is a strong emphasis on testing, as failure is not an option. The entire mission could be jeopardized if something is overlooked.

entry, descent, and landing (EDL)↗

NASA NTRS2015

Distinct Igneous APXS Rock Compositions on Mars from Pathfinder, MER and MSL

The alpha particle x-ray spectrometer (APXS) on all four Mars Rovers returned geochemical data from about 1000 rocks and soils along the combined traverses of over 50 kilometers. Here we discuss rocks likely of igneous origin, which might represent source materials for the soils and sediments identified along the traverses. Adirondack-type basalts, abundant in the plains of Gusev Crater, are primitive, olivine bearing basalts. They resemble in composition the basaltic soils encountered at all landing sites, except the ubiquitous elevated S, Cl and Zn in soils. They have been postulated to represent closely the average Martian crust composition. The recently identified new Martian meteorite Black Beauty has similar overall geochemical composition, very distinct from the earlier established SNC meteorites. The rim of the Noachian crater Endeavour, predating the sulfate-bearing Burns formation at Meridiani Planum, also resembles closely the composition of Adirondack basalts. At Gale Crater, the MSL Curiosity rover identified a felsic rock type exemplified by the mugearitic float rock JakeM, which is widespread along the traverse at Gale. While a surprise at that time, possibly related more evolved, alkaline rocks had been previously identified on Mars. Spirit encountered the Wishstone rocks in the Columbia Hills with approx. 6% Na2O+K2O, 15 % Al2O3 and low 12% FeO. Pathfinder rocks with elevated K and Na and >50% SiO2 were postulated to be andesitic. Recently Opportunity encountered the rock JeanBaptisteCharbonneau with >15% Al2O3, >50% SiO2 and approx. 10% FeO. A common characteristic all these rocks is the very low abundance of Cr, Ni and Zn, and an Fe/Mn ratio of about 50, indicating an unaltered Fe mineralogy. Beside these likely igneous rock types, which occurred always in several rocks, a few unique rocks were encountered, e.g. Bounce Rock, a pyroxene-bearing ejecta rock fragment resembling the Shergottite EETA 79001B meteorite. The APXS data can be used to relate the findings of all 4 landing sites, constrain the water to rock ratio of sediments or imply source rock provenance. Beyond that the capability to quantify important volatile elements like P, S, Cl, and Br have provided new insights into the chemistry and the environment present during the formation of the sediments.

Gellert, Ralf↗

NASA NTRS2020

JSC-Rocknest: A Large-Scale Mojave Mars Simulant (MMS) Based Soil Simulant for In-Situ Resource Utilization Water-Extraction Studies

The Johnson Space Center-Rocknest (JSC-RN) simulant was developed in response to a need by NASA's Advanced Exploration Systems (AES) In-Situ Resource Utilization (ISRU) project for a simulant to be used in component and system testing for water extraction from Mars regolith. JSC-RN was designed to be chemically and mineralogically similar to material from the aeolian sand shadow named Rocknest in Gale Crater, particularly the 1-3 wt.% low temperature (<450 ºC) water release as measured by the Sample Analysis at Mars (SAM) instrument on the Curiosity rover. Sodium perchlorate, goethite, pyrite, ferric sulfate, regular and high capacity granular ferric oxide, and forsterite were added to a Mojave Mars Simulant (MMS) base in order to match the mineralogy, evolved gases, and elemental chemistry of Rocknest. Mineral and rock components were sent to the United States Geological Survey (USGS) in Denver for mixing. Approximately 800 kg of JSC-RN was sent back to NASA in 5 gallon buckets, which were subsampled and characterized. All samples of the USGS-produced simulants had similar evolved gas profiles as a small prototype batch of JSC-RN made in JSC laboratories, with the exception of HCl, and were similar in terms of mineralogy and total chemistry. Also, all JSC-RN subsamples were homogenous and had similar mineralogy, total chemistry, and low-temperature evolved gas profiles as the Rocknest aeolian sand shadow examined with Curiosity’s instrument suite on Mars. In particular, the low temperature water releases were similar and the amount of water evolved from JSC-RN at <450 ºC was similar to the water content of Rocknest based on SAM water peak integrations. Overall, JSC-RN is ideally suited for ISRU studies of water extraction of global martian soil due to its excellent agreement with measured properties of martian soils and its proven feasibility for large-scale production.

Simulant↗

NASA NTRS2019

Seasonal Variations in Atmospheric Composition as Measured in Gale Crater, Mars

The Sample Analysis at Mars (SAM) instrument onboard the Mars Science Laboratory Curiosity rover measures the chemical composition of major atmospheric species (CO2, N2, 40Ar,O2, and CO) through a dedicated atmospheric inlet. We report here measurements of volume mixing ratios in Gale Crater using the SAM quadrupole mass spectrometer, obtained over a period of nearly 5 years (3 Mars years) from landing. The observation period spans the northern summer of MY31 and solar longitude (L(sub S)) of 175° through spring of MY 34, L(sub S) = 12°. This work expands upon prior reports of the mixing ratios measured by SAM QMS in the first 105 sols of the mission. The SAM QMS atmospheric measurements were taken periodically, with a cumulative coverage of four or five experiments per season on Mars. Major observations include the seasonal cycle of CO2, N2, and Ar, which lags approximately 20–40° of L(sub S) behind the pressure cycle driven by CO2 condensation and sublimation from the winter poles. This seasonal cycle indicates that transport occurs on faster timescales than mixing. The mixing ratio of O2 shows significant seasonal and interannual variability, suggesting an unknown atmospheric or surface process at work. The O2 measurements are compared to several parameters, including dust optical depth and trace CH4 measurements by Curiosity. We derive annual mean volume mixing ratios for the atmosphere in Gale Crater: CO2 = 0.951 (±0.003), N2 = 0.0259 (±0.0006), 40Ar = 0.0194 (±0.0004), O2 = 1.61 (±0.09) x 10(exp ‐3), and CO = 5.8 (±0.8) x 10(exp ‐4).

Gale Crater↗

NASA NTRS2013

Robust Platinum Resistor Thermometer (PRT) Sensors and Reliable Bonding for Space Missions

Platinum resistance thermometers (PRTs) provide accurate temperature measurements over a wide temperature range and are used extensively on space missions due to their simplicity and linearity. A standard on spacecraft, PRTs are used to provide precision temperature control and vehicle health assessment. This paper reviews the extensive reliability testing of platinum resistor thermometer sensors (PRTs) and bonding methods used on the Mars Science Laboratory (MSL) mission and for the upcoming Soil Moisture Active Passive (SMAP) mission. During the Mars Exploration Rover (MER) mission, several key, JPL-packaged PRTs failed on those rovers prior to and within 1-Sol of landing due to thermally induced stresses. Similar failures can be traced back to other JPL missions dating back thirty years. As a result, MSL sought out a PRT more forgiving to the packaging configurations used at JPL, and extensively tested the Honeywell HRTS-5760-B-U-0-12 sensor to successfully demonstrate suitable robustness to thermal cycling. Specifically, this PRT was cycled 2,000 times, simulating three Martian winters and summers. The PRTs were bonded to six substrate materials (Aluminum 7050, treated Magnesium AZ231-B, Stainless Steel 304, Albemet, Titanium 6AL4V, and G-10), using four different aerospace adhesives--two epoxies and two silicones--that conformed to MSL's low out-gassing requirements. An additional epoxy was tested in a shorter environmental cycling test, when the need for a different temperature range adhesive was necessary for mobility and actuator hardware late in the fabrication process. All of this testing, along with electrostatic discharge (ESD) and destructive part analyses, demonstrate that this PRT is highly robust, and not subject to the failure of PRTs on previous missions. While there were two PRTs that failed during fabrication, to date there have been no in-flight PRT failures on MSL, including those on the Curiosity rover. Since MSL, the sensor has gone through a change in construction such that the manufacturer significantly restricts the minimum temperature. However, significant subsequent testing was performed with this new version of the part to show that it indeed is still robust to at least Mars minimum temperatures of -135(sup o)C. The additional completed testing will be described. This work has resulted in a successful sensor package qualification and a reliable bonding method suitable for use over large temperature extremes.

dectector↗

NASA NTRS2013

Robust Platinum Resistor Thermometer (PRT) Sensors and Reliable Bonding for Space Missions

Platinum resistance thermometers (PRTs) provide accurate temperature measurements over a wide temperature range and are used extensively on space missions due to their simplicity and linearity. A standard on spacecraft, PRTs are used to provide precision temperature control and vehicle health assessment. This paper reviews the extensive reliability testing of platinum resistor thermometer sensors (PRTs) and bonding methods used on the Mars Science Laboratory (MSL) mission and for the upcoming Soil Moisture Active Passive (SMAP) mission. During the Mars Exploration Rover (MER) mission, several key, JPL-packaged PRTs failed on those rovers prior to and within 1-Sol of landing due to thermally induced stresses. Similar failures can be traced back to other JPL missions dating back thirty years. As a result, MSL sought out a PRT more forgiving to the packaging configurations used at JPL, and extensively tested the Honeywell HRTS-5760-B-U-0-12 sensor to successfully demonstrate suitable robustness to thermal cycling. Specifically, this PRT was cycled 2,000 times, simulating three Martian winters and summers. The PRTs were bonded to six substrate materials (Aluminum 7050, treated Magnesium AZ231-B, Stainless Steel 304, Albemet, Titanium 6AL4V, and G-10), using four different aerospace adhesives--two epoxies and two silicones--that conformed to MSL's low out-gassing requirements. An additional epoxy was tested in a shorter environmental cycling test, when the need for a different temperature range adhesive was necessary for mobility and actuator hardware late in the fabrication process. All of this testing, along with electrostatic discharge (ESD) and destructive part analyses, demonstrate that this PRT is highly robust, and not subject to the failure of PRTs on previous missions. While there were two PRTs that failed during fabrication, to date there have been no in-flight PRT failures on MSL, including those on the Curiosity rover. Since MSL, the sensor has gone through a change in construction such that the manufacturer significantly restricts the minimum temperature. However, significant subsequent testing was performed with this new version of the part to show that it indeed is still robust to at least Mars minimum temperatures of -135 degrees Centigrade. The additional completed testing will be described. This work has resulted in a successful sensor package qualification and a reliable bonding method suitable for use over large temperature extremes

Platinum Resistor Thermometer (PRT)↗

NASA NTRS2016

Mineralogy, Provenance, and Diagenesis of a Potassic Basaltic Sandstone on Mars: CheMin X-Ray Diffraction of the Windjana Sample (Kimberley Area, Gale Crater)

The Windjana drill sample, a sandstone of the Dillinger member (Kimberley formation, Gale Crater, Mars), was analyzed by CheMin X-ray diffraction (XRD) in the MSL Curiosity rover. From Rietveld refinements of its XRD pattern, Windjana contains the following: sanidine (21% weight, approximately Or(sub 95)); augite (20%); magnetite (12%); pigeonite; olivine; plagioclase; amorphous and smectitic material (approximately 25%); and percent levels of others including ilmenite, fluorapatite, and bassanite. From mass balance on the Alpha Proton X-ray Spectrometer (APXS) chemical analysis, the amorphous material is Fe rich with nearly no other cations-like ferrihydrite. The Windjana sample shows little alteration and was likely cemented by its magnetite and ferrihydrite. From ChemCam Laser-Induced Breakdown Spectrometer (LIBS) chemical analyses, Windjana is representative of the Dillinger and Mount Remarkable members of the Kimberley formation. LIBS data suggest that the Kimberley sediments include at least three chemical components. The most K-rich targets have 5.6% K2O, approximately 1.8 times that of Windjana, implying a sediment component with greater than 40% sanidine, e.g., a trachyte. A second component is rich in mafic minerals, with little feldspar (like a shergottite). A third component is richer in plagioclase and in Na2O, and is likely to be basaltic. The K-rich sediment component is consistent with APXS and ChemCam observations of K-rich rocks elsewhere in Gale Crater. The source of this sediment component was likely volcanic. The presence of sediment from many igneous sources, in concert with Curiosity's identifications of other igneous materials (e.g.,mugearite), implies that the northern rim of Gale Crater exposes a diverse igneous complex, at least as diverse as that found in similar-age terranes on Earth.

Treiman, Allan H.↗

NASA NTRS2015

Jarosite in Gale Crater, Mars: The Importance of Temporal and Spatial Variability and Implications for Habitiability

The Curiosity rover has recently found evidence for small amounts of jarosite, a ferric sulfate, in the Pahrump Hills region at the base of Aeolis Mons (Mount Sharp), Gale crater. While jarosite has been described previously at other locations on Mars, including several sites at Meridiani Planum (explored by the Opportunity rover; and Mawrth Vallis (by remote MRO-CRISM observations; this is the first identification in Gale. Jarosite is interpreted to be a mineral indicator of acidic conditions (pH less than 4; on Earth, it is most commonly found in acid rock-drainage or acid sulfate soil environments. However, jarosite has also been described from a number of terrestrial environments where widespread acidic conditions are not prevalent. As a case study, we describe here an occurrence of sedimentary pyrite nodules that have been variably oxidized in situ to gypsum, schwertmannite, K-/Na-jarosite and iron oxides in a polar desert environment on Devon Island, Nunavut, Canada. Remarkably, these nodules occur in loosely consolidated carbonate sediments, which would have required a higher pH environment at their time of formation and deposition. Thus, acidic conditions may only exist at a small (sub-cm) scale or in a restricted temporal window in an otherwise well-buffered environment. On Devon Island, the jarosite occurs in the most oxidized nodules and is never associated directly with pyrite. Schwertmannite, a metastable iron oxyhydroxysulfate that can form at pH higher than that required for jarosite, occurs in association with partially oxidized pyrite. The paragenetic sequence observed here suggests initial formation of schwertmannite and late-stage precipitation of jarosite in restricted micro-environments, possibly forming via transformation of an amorphous schwertmannite-like phase. While the carbonate environment on Devon Island differs significantly from that of Gale crater, i.e., where we find predominantly basaltic sedimentary rocks, this terrestrial analog provides insight into the significance of jarosite with respect to habitability. For example, the variable abundance of jarosite on Mars and possibly in Gale crater points to potentially localized conditions favorable for jarosite formation. Interestingly, small amounts of sulfide minerals have also been detected by Curiosity at Yellowknife Bay; oxidation of sulfide minerals at Pahrump could explain the presence of small amounts of jarosite. The iron-rich rocks at Pahrump may also represent relatively altered basaltic sediments, or they could be sediments that were altered further by a fluid with a distinct, possibly more acidic, composition. In addition, the abundance of iron-rich amorphous material in Gale rocks allows for the possibility that pre-cursor, iron-bearing phases transform to jarosite post-depositionally. Thus, the occurrence of jarosite at Pahrump could reflect changing paleoenvironmental conditions, though continuing study of its context and textural relationships should provide a fuller understanding of the significance of this mineral to past fluid compositions and past habitability at Gale crater.

Leveille, R. J.↗

NASA NTRSDate not supplied

First-results from the Perseverance SHERLOC Investigation: Aqueous Alteration Processes and Implications for Organic Geochemistry in Jezero Crater, Mars

The Perseverance rover landed in Jezero crater, a site selected to fulfill the Mars-2020 mission goals of characterizing the geology of habitable environments and searching for signs of life while collecting samples for return to Earth [1]. Jezero hosted an open-basin lake during the late Noachian/early Hesperian (~3.7 Ga) [1-2], has units associated with the largest carbonate deposit identified on Mars [3-4], and has a well-preserved delta with clay and carbonate-bearing sediments, well-suited to preservation of organics [1,3-4]. Investigating the nature of organics and aqueous environments within their geologic con-text allows us to understand important aqueous processes and determine habitability within Jezero crater. Previous in situ landed measurements of organics could not resolve their spatial and mineralogical con-text [5-6]. Although Martian meteorites lack geological context, the spatial distribution of organic compounds in Martian meteorites have allowed recognition of an association between aqueous processes and organics [7-8]. Here, we show for the first time in-situ associations between carbonate-forming ultramafic alteration process, later stage aqueous sulfate and perchlorate formation, and organics on the Martian surface. Methodology and geological context: We use the Perseverance rover’s SHERLOC instrument (Scanning Habitable Environments with Raman and Lumines-ence of Organics and Chemicals), a deep-ultraviolet fluorescence and Raman scattering spectrometer capable of mapping the organic and mineral composition with a spatial resolution of 100 μm resolution to report the presence of organics and aqueously formed minerals at Jezero crater [9]. These spectral detections were compared with co-located images obtained with the autofocus context imager (ACI) and the WATSON camera for textural analysis [9]. As of writing, the Per-severance rover has abraded five targets that were measured with the SHERLOC instrument. The five targets are located in two different orbitally-identified geological units within the floor of Jezero crater; the Crater Floor Fractured Rough unit (CF-Fr) and the Séítah region within the Crater Floor Fractured 1 unit (CF-F1) [10]. In orbital infrared spectroscopic data, the CF-Fr unit is associated with pyroxene spectral signatures and minor alteration, while the Séítah region is associated with olivine and minor Mg-rich carbonates and clays [3-4,10]. Carbonation of ultramafic protolith recorded within Jezero crater: All scans of abraded targets within the Séítah region reveal strong peaks at 1080–1090 cm−1 consistent with carbonate and peak singlets or doublets at 820–840 cm−1 attributed to olivine (Fig. 1), consistent with orbital infrared observations. Our detailed micron-scale petrographic and spectroscopic evidence shows that these carbonates formed through carbonation of an ultramafic protolith. The supporting observations include: (1) Carbonate cation compositions match those of olivine, suggesting mixed Fe- and Mg-olivine gave rise to mixed Fe- and Mg-carbonates, similar to observations of ultramafic systems on Earth and within Martian meteorites [3-4,7-8]. (2) The ob-served carbonates co-occur with hydrated materials, gypsum, and potentially aqueously-formed phases, amorphous silicates and phosphate. (3) The spectral and textural variation of olivine and carbonate dominated zones and olivine-carbonate mixtures within both primary grains and interstitial zones are expected for carbonated ultramafic protoliths. (4) These mineral associations and textures closely resemble those observed within the ALH84001 and Nakhlite meteorites attributed to olivine carbonation on Mars [6-7]. Taken together, micron-scale SHERLOC documentation of these phenomena bridge previous orbital and meteorite observations and demonstrate in-situ regionally extensive (~106 km2) ultramafic alteration resulting in geo-logical deposition of carbonates. Furthermore, we observe that olivine carbonation was involved in preserving and possibly synthesizing organics, which makes this environment potentially habitable, as previously suggested in [1,3-4] (Fig. 1). Late-stage aqueous perchlorate and sulfate in Jezero crater: An abrasion target within the CF-Fr unit contains combinations of high intensity 950-955 cm−1 peaks and minor 1090-1095 cm−1 and 1150-1155 cm−1 peaks that are spectral fits to anhydrous perchlorate (Fig. 1). Some spectra show a combination of 950-955 cm−1 peaks with equally strong 1010-1020 cm−1 peaks, low intensity broad features at 1120 cm−1, and occasional broad 3450 cm−1 hydration (-OH) features, indicating a mixture of Ca-sulfate and perchlorate that is minimally hydrated (Fig. 1). The detections of per-chlorates within Jezero crater differ from previous measurements (e.g. Phoenix lander, Curiosity rover, Tissint meteorite [7,11]) because they are observed to be intimately related to aqueous processes including sulfate formation, they present as a secondary white void-fill occurring within the interior of the rock, and they are found to likely be Na-perchlorate. implications for their formation: Three different types of organics embedded within three different lithologies were observed within the abraded targets. Organics associated with low intensity ~340 nm fluorescence were widespread within targets with no apparent association to particular minerals (Fig. 1). Organics associated with ~305 nm and ~275 nm fluorescence correlated with sulfates within the Bellegarde target in the CF-Fr unit, while organics associated with high intensity ~340 nm fluorescence correlated with carbonate, phosphate, and amorphous silicate mixtures within the Garde target in the Séítah region (Fig. 1). Although assignment of fluorescence signatures to specific organic compounds is not conclusive, ~340 nm fluorescence is generally more consistent with 2-ring aromatic organics, ~275 nm fluorescence is more consistent with 1-ring aromatic organics, and ~305 nm fluorescence can be created by either 2- or 1-ring aromatics [12]. These observations indicate that the strongest fluorescence signatures interpreted as organics were found in materials associated with aqueous processes, i.e. sulfate- and carbonate-bearing materials, suggesting both brines and ultramafic carbonation aqueous environments were capable of preserving organics on ancient Mars. In Martian meteorites, simple aromatic organics proposed to have been synthesized through aqueous processes can be found within minerals associated with olivine carbonation and in spatial association with perchlorate and sulfate materials [7-8], similar to SHERLOC observations. Hence, we advance an abiotic aqueous synthesis origin for the organics although we cannot rule out the presence of organics from meteoritic in-fall or putative organic biosignatures. Detailed analyses will be required upon return of these materials to Earth.

E L Scheller↗