The Mars Science Laboratory Mission (MSL), scheduled to land on Mars in the summer of 2012, consists of a rover and a scientific payload designed to identify and assess the habitability, geological, ...and environmental histories of Gale crater. Unraveling the geologic history of the region and providing an assessment of present and past habitability requires an evaluation of the physical and chemical characteristics of the landing site; this includes providing an in-depth examination of the chemical and physical properties of Martian regolith and rocks. The MSL Sample Acquisition, Processing, and Handling (SA/SPaH) subsystem will be the first in-situ system designed to acquire interior rock and soil samples from Martian surface materials. These samples are processed and separated into fine particles and distributed to two onboard analytical science instruments SAM (Sample Analysis at Mars Instrument Suite) and CheMin (Chemistry and Mineralogy) or to a sample analysis tray for visual inspection. The SA/SPaH subsystem is also responsible for the placement of the two contact instruments, Alpha Particle X-Ray Spectrometer (APXS), and the Mars Hand Lens Imager (MAHLI), on rock and soil targets. Finally, there is a Dust Removal Tool (DRT) to remove dust particles from rock surfaces for subsequent analysis by the contact and or mast mounted instruments (e.g. Mast Cameras (MastCam) and the Chemistry and Micro-Imaging instruments (ChemCam)).
During Martian solar days 57–100, the Mars Science Laboratory Curiosity rover acquired and processed a solid (sediment) sample and analyzed its mineralogy and geochemistry with the Chemistry and ...Mineralogy and Sample Analysis at Mars instruments. An aeolian deposit—herein referred to as the Rocknest sand shadow—was inferred to represent a global average soil composition and selected for study to facilitate integration of analytical results with observations from earlier missions. During first‐time activities, the Mars Hand Lens Imager (MAHLI) was used to support both science and engineering activities related to sample assessment, collection, and delivery. Here we report on MAHLI activities that directly supported sample analysis and provide MAHLI observations regarding the grain‐scale characteristics of the Rocknest sand shadow. MAHLI imaging confirms that the Rocknest sand shadow is one of a family of bimodal aeolian accumulations on Mars—similar to the coarse‐grained ripples interrogated by the Mars Exploration Rovers Spirit and Opportunity—in which a surface veneer of coarse‐grained sediment stabilizes predominantly fine‐grained sediment of the deposit interior. The similarity in grain size distribution of these geographically disparate deposits support the widespread occurrence of bimodal aeolian transport on Mars. We suggest that preservation of bimodal aeolian deposits may be characteristic of regions of active deflation, where winnowing of the fine‐sediment fraction results in a relatively low sediment load and a preferential increase in the coarse‐grained fraction of the sediment load. The compositional similarity of Martian aeolian deposits supports the potential for global redistribution of fine‐grained components, combined with potential local contributions.
Key Points
Curiosity acquired and examined its first solid sample at the Rocknest sand shadow
MAHLI images were critical in the science investigation of Rocknest materials
MAHLI images played a critical role supporting first‐time engineering activities
We analyze archival Chandra X-ray Observatory observations of Jupiter to search for emission from the Galilean moons. X-ray emission has previously been reported from Io and Europa using a subset of ...these data. We confirm this detection, and marginally detect X-ray emission from both Ganymede and Callisto as well. The X-ray spectrum of Europa is strongly peaked around the neutral oxygen fluorescence line (525 eV), while Io's has peaks at both oxygen and sulfur (2308 eV) plus a broad continuum between 350 and 5000 eV. Ganymede's spectrum is similar to Io's, but without the sulfur peak. A few events, mostly clustered around the oxygen line, are detected from Callisto. Using measurements by the Galileo mission of the specific intensity of ambient protons and electrons, we model the X-ray spectra and flux of the moons from two processes: particle-induced X-ray emission (PIXE) from the impact of energetic protons and X-ray emission from electron bremsstrahlung. With uncertainties of a factor of a few, the electron bremsstrahlung and PIXE models overestimate the X-ray flux from Europa, preventing us from making a definitive statement about the origin of the X-ray emission. The PIXE model of Io predicts emission lines at O and S similar to those observed, but underestimates their flux by nearly two orders of magnitude. Based on this discrepancy in the PIXE flux, combined with the detected broadband continuum in the spectrum, we conclude that the X-ray emission from Io is due to electron bremsstrahlung. Likewise, because of Ganymede's broad continuum, we tentatively conclude that its X-ray emission is also due to electron bremsstrahlung. Callisto is too faint in the X-rays to draw any conclusion. Obtaining in situ X-ray observations of the moons would provide a direct measurement of their elemental composition.
Measuring the physical properties of geological materials is important for understanding geologic history. Yet there has never been an instrument with the purpose of measuring mechanical properties ...of rocks sent to another planet. The Mars Science Laboratory (MSL) rover employs the Powder Acquisition Drill System (PADS), which provides direct mechanical interaction with Martian outcrops. While the objective of the drill system is not to make scientific measurements, the drill's performance is directly influenced by the mechanical properties of the rocks it drills into. We have developed a methodology that uses the drill to indicate the uniaxial compressive strengths of rocks through comparison with performance of an identically assembled drill system in terrestrial samples of comparable sedimentary class. During this investigation, we utilize engineering data collected on Mars to calculate the percussive energy needed to maintain a prescribed rate of penetration and correlate that to rock strength.
Plain Language Summary
The one tool that personifies the field geologist is a rock hammer. The field geologist will use his/her hammer to expose fresh rock surfaces allowing examination of unweathered rock. He/she will also use it to determine qualitative rock strengths in the field. While Curiosity does not carry a traditional rock hammer, it does have a drill system. The ability to fail rock with a hammering mechanism and the ability to use the performance data from the drill system presented the authors with an innovative concept. The drill could be used as an instrument to indicate the strength of rocks, except that the drill's measurement is better. Where the field geologist has only his/her tactile senses, Curiosity is instrumented with sensors that measure rates of penetration, percussive energy, and weight on bit allowing a quantifiable measurement of rock strength. The article describes the methodologies that allow the drill system aboard the Mars Science Laboratory rover to also serve as a scientific instrument and reports the compressive strength of the rocks drilled on Mars using these methods.
Key Points
A nonstandard method was employed to provide a scientific measurement on the surface of Mars
Sedimentary structure matters when determining rock strength
Strengthwise, the sedimentary rocks at Gale crater are more akin to younger sedimentary rock on Earth
The effects of radiation on the survivability of key biosignatures are a driving factor in exploration strategies throughout the solar system. Ultraviolet (UV) radiation, especially shorter ...wavelength UVC radiation, is known to be damaging to organisms and to potential organic biosignatures; however, the interaction of UV radiation with minerals and rocks is not well understood. Constraining the survivability of organics and generation of habitable zones requires assessment of physical parameters such as penetration depth of UV photons. This type of information helps to identify to what extent rocks and minerals can provide effective shielding against UV radiation and is especially important on Mars, where the surface chemistry is more oxidizing, and the radiation environment is more extreme than on Earth. Using pressed pellets of natural gypsum, kaolinite, Mars simulant basalt, and welded tuff, we measured the spectral transmittance of each in the wavelength range of 220–400 nm. Although transmittance drops off quickly with depth, detectable levels of UV can penetrate >500 μm in each material. Each substrate allowed higher transmittance of UVC radiation than of longer wavelength UVA/B radiation, possibly as a result of surface reflectance and internal scattering properties. This could result in increased subsurface photolysis of organic compounds and biosignatures. We have used the transmittance data collected herein to constrain the lifetimes of several organic molecules in the Martian subsurface. These results will also have implications for organic analyses to be conducted by Mars 2020 and could be used to better constrain the SHERLOC/Mars 2020 interrogation volume.
Plain Language Summary
Some types of radiation, including ultraviolet (UV) radiation, can be damaging to organisms and to organic molecules which could potentially be used as evidence of life. For this reason it is important to understand how rocks and minerals can provide protection against these types of radiation. In this study we prepared pellets of varying thickness made of different types of rocks and minerals relevant to Mars exploration and measured the amount of UV light that was able to pass through them.
These data were used in combination with knowledge of the UV environment on Mars in order to determine what the UV radiation dosage would be under various thicknesses of the rocks and minerals we had analyzed. The percentage of UV radiation that was able to pass through the rock and mineral pellets was found to be higher than we expected, which suggests that this type of damaging radiation would be able to penetrate further into rock and mineral environments. This information was then used to determine approximately how long different types of organic molecules could be expected to survive if buried under different depths in rock and mineral materials.
Key Points
The interaction of UV photons with rocks and minerals has implications for habitability as well as organic biosignature preservation and detection
Transmittance of UV radiation has been determined for four types of natural rocks and minerals that are relevant for Mars exploration
UV photons can penetrate to depths greater than anticipated, resulting in a large effective radiation dosage over geological timescales
During its first year of operation, the Perseverance rover explored the cratered and fractured floor of Jezero crater on Mars. Here, we report the use of the Scanning Habitability Environments with ...Raman and Luminescence for Organics and Chemicals (SHERLOC) imaging system that includes two high-resolution cameras, the Autofocus and Contextual Imager (ACI) and Wide Angle Topographic Sensor for Operations and eNgineering (WATSON). ACI is a fixed focus gray scale imager with a resolution of 10.1 μm/pixel whereas WATSON is a variable field of view, variable focus imager capable of resolution down to 14 μm/pixel. WATSON is a reflight of the MArs Hand Lens Imager (MAHLI) imager and has similar capabilities. During first-time activities, WATSON was used to support both science and engineering operations related to sample and abrasion patch assessment and sample collection and caching. WATSON also documented the deployment of the Ingenuity helicopter. The Crater Floor Campaign identified two primary rock units, the Máaz formation and the Séítah formation, which have been interpreted as lava flows and an olivine cumulate, respectively. Interpretation of rock textures with WATSON and ACI images was limited to abraded surfaces because unmodified outcrop surfaces (herein termed “natural surfaces”) show high degrees of dust covering, wind abrasion, and coating by secondary mineral products. WATSON and ACI images support the hypothesis that the material of both the Máaz and Séítah formations consists of largely aqueously altered mafic materials with varying igneous origins.
•The Curiosity rover acquired and examined its first in-situ sample at the Rocknest deposit.•Partial use of this material was to demonstrate organic cleanliness of the sampling hardware.•First time ...engineering activities of the MSL sampling (SA/SPaH) hardware were accomplished.
During its 57th through 100th martian days (sols) in Gale Crater, the Mars Science Laboratory (MSL) Curiosity rover performed its first sample acquisition and processing of solid, granular sample. Samples were extracted from an aeolian sand deposit at a location called Rocknest. The Rocknest sampling site was identified to fit the prelaunch scientific and engineering requirements for this first time activity. Collected material was processed and delivered to two analytical instruments, Chemistry and Mineralogy (CheMin) and Sample Analysis at Mars (SAM), that both require delivery of a specific particle size range so that they can perform analyses to determine sample mineralogy and geochemistry. The choice of an aeolian sand deposit was based on requirements to ingest non-lithified, particulate sample for decontamination of the Sample Acquisition/Sample Processing and Handling (SA/SPaH) hardware, as well as to provide an opportunity to compare analytical results to aeolian deposits from elsewhere on the martian surface.
•Further investigation of the first two drill sites on Mars.•MSL's ChemCam provides spatial context for samples collected by drilling process.•Able to investigate compositional change with depth in ...the drill hole.•Capable of determining the contribution of alteration materials in the drill tailings.•Little to no variation in chemistry seen between the two drill sites.
The ChemCam instrument on the Mars Science Laboratory rover analyzed the rock surface, drill hole walls, tailings, and unprocessed and sieved dump piles to investigate chemical variations with depth in the first two martian drill holes and possible fractionation or segregation effects of the drilling and sample processing. The drill sites are both in Sheepbed Mudstone, the lowest exposed member of the Yellowknife Bay formation. Yellowknife Bay is composed of detrital basaltic materials in addition to clay minerals and an amorphous component. The drill tailings are a mixture of basaltic sediments and diagenetic material like calcium sulfate veins, while the shots on the drill site surface and walls of the drill holes are closer to those pure end members. The sediment dumped from the sample acquisition, processing, and handling subsystem is of similar composition to the tailings; however, due to the specifics of the drilling process the tailings and dump piles come from different depths within the hole. This allows the ChemCam instrument to analyze samples representing the bulk composition from different depths. On the pre-drill surfaces, the Cumberland site has a greater amount of CaO and evidence for calcium sulfate veins, than the John Klein site. However, John Klein has a greater amount of calcium sulfate veins below the surface, as seen in mapping, drill hole wall analysis, and observations in the drill tailings and dump pile. In addition, the Cumberland site does not have any evidence of variations in bulk composition with depth down the drill hole, while the John Klein site has evidence for a greater amount of CaO (calcium sulfates) in the top portion of the hole compared to the middle section of the hole, where the drill sample was collected.
Our aim in this investigation was to demonstrate the potential of the high-resolution electrospray ionization ion mobility spectrometry (ESI-IMS) technique as an analytical separation tool in ...analyzing biomolecular mixtures to pursue astrobiological objectives of searching for the chemical signatures of life during an in-situ exploration of solar system bodies. Because amino acids represent the basic building blocks of life, we used common amino acids to conduct the first part of our investigation, which is being reported here, to demonstrate the feasibility of using the ESI-IMS technique for detection of the chemical signatures of life. The ion mobilities of common amino acids were determined by electrospray ionization ion mobility spectrometry using three different drift gases (N2, Ar, and CO2). We demonstrated that the selectivity can be vastly improved in ion mobility spectroscopy (IMS) in detecting organic molecules by using different drift gases. When a judicial choice of drift gas is made, a vastly improved separation of two different amino acid ions resulted. It was found that each of the studied amino acids could be uniquely identified from the others, with the exception of alanine and glycine, which were never separable by more then 0.1 ms. This unique identification is a result of the different polarizabilities of the various drift gases. In addition, a better separation was achieved by changing the drift voltage in successive experimental runs without significantly degrading the resolution. We also report the result of our analysis of liquid samples containing mixtures of amino acids.
We have identified and characterized a basaltic Mars simulant that is available as whole rocks, sand and dust. The source rock for the simulant is a basalt mined from the Tertiary Tropico Group in ...the western Mojave Desert. The Mojave Mars Simulant (MMS) was chosen for its inert hygroscopic characteristics, its availability in a variety of forms, and its physical and chemical characteristics. The MMS dust and MMS sand are produced by mechanically crushing basaltic boulders. This is a process that more closely resembles the weathering/comminution processes on Mars where impact events and aerodynamic interactions provide comminution in the (relative) absence of water and organics. MMS is among the suite of test rocks and soils that was used in the development of the 2007/8 Phoenix Scout and is being used in the 2009 Mars Science Laboratory (MSL) missions. The MMS development team is using the simulant for research that centers on sampling tool interactions in icy soils. Herein we describe the physical properties and chemical composition of this new Mars simulant.
PDF
