Scott VanBommel

Washington University in St. Louis | WUSTL , Wash U · Department of Earth and Planetary Sciences

Plain Language Summary The Amapari Marker Band (AMB) at Gale crater forms a distinct, dark‐toned, resistant horizon identified from orbit within rock layers of the Mg‐sulfate‐bearing, central mound. Curiosity recently investigated the AMB and found a lower rippled layer, consistent with a shallow lake, contrasting with windblown sediment deposition...

This paper reviews the phosphate phases in meteorites and those measured by landed spacecraft, what they reveal about past igneous and aqueous conditions on Mars, and important implications for potential prebiotic chemistry, past habitability, and potential biosignatures that could be detected in samples returned from Mars. A review of the 378 mart...

The Planetary Instrument for X-ray Lithochemistry (PIXL) onboard the Perseverance rover, part of NASA’s Mars 2020 mission, has the first camera system that utilizes active light sources to generate multispectral data directly on a planetary surface. PIXL collects the multispectral data using three different components in the Optical Fiducial System...

Martian soils are critically important for understanding the history of Mars, past potentially habitable environments, returned samples, and future human exploration. This study examines soil crusts on the floor of Jezero crater encountered during initial phases of the Mars 2020 mission. Soil surface crusts have been observed on Mars at other locat...

The first samples collected by the Mars 2020 mission represent units exposed on the Jezero Crater floor, from the potentially oldest Séítah formation outcrops to the potentially youngest rocks of the heavily cratered Máaz formation. Surface investigations reveal landscape‐to‐microscopic textural, mineralogical, and geochemical evidence for igneous...

The Mars Science Laboratory rover Curiosity encountered nodules rich in manganese and phosphorus while exploring the Knockfarril Hill member of Gale crater on Mars. Deconvolution of X-ray spectroscopy data acquired by the Alpha Particle X-ray Spectrometer (APXS) at the spectral level indicate P2O5 concentrations possibly in excess of 18 wt% and MnO...

The Glen Torridon stratigraphic sequence marks the transition from the low energy lacustrine‐dominated Murray formation (Mf) (Jura member: Jm) to the more diverse Carolyn Shoemaker formation (CSf) (Knockfarril Hill member: Knockfarril Hill; Glasgow member: Glasgow). This transition defines a change in depositional setting. Alpha Particle X‐ray Spec...

The geological units on the floor of Jezero crater, Mars, are part of a wider regional stratigraphy of olivine-rich rocks, which extends well beyond the crater. We investigate the petrology of olivine and carbonate-bearing rocks of the Séítah formation in the floor of Jezero. Using multispectral images and x-ray fluorescence data, acquired by the P...

Geochemical analyses by X-ray spectrometry and laser-induced breakdown spectroscopy (LIBS) instruments on the surface of Mars enable detailed studies of surface materials. The two techniques are utilized in concert by rovers to glean information in a complementary fashion. However, fundamental differences in how these analytical techniques function...

In August 2015, the Curiosity Mars rover discovered tridymite, a high‐temperature silica polymorph, in Gale crater. The existing model for its occurrence suggests erosion and detrital sedimentation from silicic volcanic rocks in the crater rim or central peak. The chemistry and mineralogy of the tridymite‐bearing rocks, however, are not consistent...

The resistant ~50 m thick Vera Rubin ridge (VRR) situated near the base of Mount Sharp, Gale crater, Mars, has been deemed a high priority science target for the Mars Science Laboratory mission. This is because of (1) its position at the base of the 5 km layered strata of Mount Sharp and (2) the detection of hematite from orbit, indicating that it...

Alongside major and minor elements, trace elements in Martian samples quantified through geochemical analyses by the Mars Science Laboratory (MSL, Curiosity) Alpha Particle X-ray Spectrometer (APXS) provide insight into ancient environments on Mars. APXS spectrum simulations facilitated the characterization of trace elements measured by the APXS un...

In terrestrial instruments for X-ray emission analysis (e.g. X-ray fluorescence, electron microprobe) the angle of excitation and the angle of characteristic X-ray emission by samples are typically well-defined. This is not the case for the Mars rovers' alpha particle X-ray spectrometers, necessitating use of "effective" angles in any fundamental p...

This paper is Open Access in the AGU journal, Earth and Space Science. You can download it for free from: https://doi.org/10.1029/2018EA000482 Abstract: Mineral‐filled fractures (veins) are valuable indicators of deformation and fluid flow within a sedimentary package. Information obtained from vein morphology, texture, and chemistry may elucidate...

Simulation software was developed that accurately emulates the response of the Mars Science Laboratory (MSL) Alpha Particle X-ray Spectrometer (APXS) under variable experimental conditions including temperature, standoff, measurement duration, and target composition. Around 450 spectra collected on Mars provide the spectral library for calibration...

Concretions are prevalent features in the generally lacustrine deposits of the Murray formation in Gale crater. In this work, we document the morphologic, textural, and chemical properties of these concretions throughout 300 meters of Murray formation stratigraphy from Mars Science Laboratory observations between Sols 750-1900. We interpret these o...

Alpha Particle X-ray Spectrometer (APXS) results for Phase 2 of the Bagnold Dunes campaign, focusing on the linear dunes, complement those from Phase 1 (barchan dunes) and add to our understanding of active Martian dune systems. This work highlights both compositional similarities and differences across the dune field. The concentration of elements...

We report the results of geological studies by the Opportunity Mars rover on the Endeavour Crater rim. Four major units occur in the region (oldest to youngest): the Matijevic, Shoemaker, Grasberg and Burns formations. The Matijevic formation, consisting of fine-grained clastic sediments, is the only pre-Endeavour-impact unit and might be part of t...

The Opportunity rover investigated a gentle swale on the rim of Endeavour crater called Marathon Valley where a series of bright planar outcrops are cut into polygons by fractures. A wheel scuff performed on one of the soil-filled fracture zones revealed the presence of three endmembers identified on the basis of Pancam multispectral imaging observ...

Zinc and germanium enrichments have been discovered in sedimentary rocks in Gale Crater, Mars, by the Alpha Particle X-ray Spectrometer (APXS) on the rover Curiosity. Concentrations of Zn (910 ± 840 ppm) and Ge (65 ± 58 ppm) are 10s-100s of times greater than in Martian meteorites and estimates for average silicate Mars. Enrichments occur in divers...

The Alpha Particle X-ray Spectrometer (APXS) onboard the Mars rover Curiosity conducts high-precision in situ chemical measurements of rocks and regolith. Target surfaces are not always flat and thus can pose issues for interpretations that assume such. Here, we investigate when variable target relief is an important effect to consider for APXS tar...

NOTE -- this article is open access on at http://dx.doi.org/10.1017/S1431927617011370. . . Curiosity Rover Mars Hand Lens Imager (MAHLI) Views of the Sediments and Sedimentary Rocks of Gale Crater, Mars - Volume 23 Issue S1 - Kenneth S. Edgett, R. Aileen Yingst, Michelle E. Minitti, Megan R. Kennedy, Gillian M. Krezoski, Deirdra M. Fey, Stephane L...

We present APXS data for the active Bagnold dune field within the Gale impact crater (MSL mission). We derive an APXS-based Average Basaltic Soil (ABS) composition for Mars based on past and recent data from the MSL and MER missions. This represents an update to the Taylor and McLennan (2009) average martian soil, and facilitates comparison across...

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The Alpha Particle X-ray spectrometer (APXS) onboard the Curiosity rover at the Kimberley location within Gale crater, Mars, analyzed basaltic sandstones that are characterized by potassium enrichments of two to eight times estimates for average martian crust. They are the most potassic rocks sampled on Mars to date. They exhibit elevated Fe, Mg, M...

The Curiosity rover observed high Mn abundances (>25 wt % MnO) in fracture-filling materials that crosscut sandstones in the Kimberley region of Gale crater, Mars. The correlation between Mn and trace metal abundances plus the lack of correlation between Mn and elements such as S, Cl, and C, reveals that these deposits are Mn oxides rather than eva...

Mars Reconnaissance Orbiter HiRISE images and Opportunity rover observations of the ~22 km wide Noachian age Endeavour Crater on Mars show that the rim and surrounding terrains were densely fractured during the impact crater-forming event. Fractures have also propagated upward into the overlying Burns formation sandstones. Opportunity’s observation...

The Alpha Particle X-Ray Spectrometer (APXS) determines the chemical composition of Martian rocks and soils on-board both active National Aeronautics and Space Administration (NASA) rovers using X-ray emission spectroscopy through complementary particle-induced X-ray emission (PIXE) and X-ray fluorescence (XRF) excitation methods. A single APXS spe...

Alpha Particle X-ray Spectrometer (APXS) rock analyses represent bulk geochemical compositions and integrated historical records of igneous protolith(s), physical processing, overprinting alteration, and dust coverage. The APXS measures abundances of major, minor, and some trace elements (Cr, Ni, Zn, Br, Ge) of ~1.7 cm spots on rocks and soils. Sin...

Since the MSL Curiosity rover arrived at the lower most slopes of Mount Sharp, the APXS instrument has encountered four distinct bedrock compositions, two of which have not previously been encountered on the mission, indicating different source regions and/or post-depositional alteration/diagenetic histories. Raised, resistant nodular features are...

Germanium enrichment in Gale Crater sedimentary rocks may serve as a promising tracer for protolith compositions and alteration history.

Reducing placement uncertainty and improving interpretation of APXS raster targets with visually distinct phases through MAHLI images and APXS spectral data.

Modern Martian dust is similar in composition to the global soil unit and bulk basaltic Mars crust, but it is enriched in S and Cl. The Alpha Particle X-ray Spectrometer (APXS) on the Mars Science Laboratory Curiosity rover analyzed air fall dust on the science observation tray (o-tray) in Gale Crater to determine dust oxide compositions. The o-tra...

The Mars Science Laboratory (MSL) rover, Curiosity, has a titanium science observation tray (o-tray), upon which portions from drilled and scooped martian samples can be delivered for analyses by the alpha-particle X-ray spectrometer (APXS). The standard APXS calibration approach to derive elemental concentrations cannot be applied to samples on th...

The MSL APXS identified various new rock types along the traverse at Gale Crater during the first 450 sol. These will be presented and compared to MER.

The Curiosity rover discovered fine-grained sedimentary rocks, which are inferred to represent an ancient lake and preserve evidence of an environment that would have been suited to support a martian biosphere founded on chemolithoautotrophy. This aqueous environment was characterized by neutral pH, low salinity, and variable redox states of both i...

Sedimentary rocks examined by the Curiosity rover at Yellowknife Bay, Mars, were derived from sources that evolved from approximately average Martian crustal composition to one influenced by alkaline basalts. No evidence of chemical weathering is preserved indicating arid, possibly cold, paleoclimates and rapid erosion/deposition. Absence of predic...

The first four rocks examined by the Mars Science Laboratory Alpha Particle X-ray Spectrometer indicate that Curiosity landed in a lithologically diverse region of Mars. These rocks, collectively dubbed the Bradbury assemblage, were studied along an eastward traverse (sols 46-102). Compositions range from Na- and Al-rich mugearite Jake_Matijevic to...

Sedimentary rocks examined by the Curiosity rover at Yellowknife Bay, Mars, were derived from sources that evolved from an approximately average martian crustal composition to one influenced by alkaline basalts. No evidence of chemical weathering is preserved, indicating arid, possibly cold, paleoclimates and rapid erosion and deposition. The absen...

Sedimentary rocks at Yellowknife Bay (Gale crater) on Mars include mudstone sampled by the Curiosity rover. The samples, John Klein and Cumberland, contain detrital basaltic minerals, calcium sulfates, iron oxide or hydroxides, iron sulfides, amorphous material, and trioctahedral smectites. The John Klein smectite has basal spacing of ~10 angstroms...

We determined radiogenic and cosmogenic noble gases in a mudstone on the floor of Gale Crater. A K-Ar age of 4.21 ± 0.35 billion years represents a mixture of detrital and authigenic components and confirms the expected antiquity of rocks comprising the crater rim. Cosmic-ray–produced 3He, 21Ne, and 36Ar yield concordant surface exposure ages of 78...

The ChemCam instrument, which provides insight into martian soil chemistry at the submillimeter scale, identified two principal soil types along the Curiosity rover traverse: a fine-grained mafic type and a locally derived, coarse-grained felsic type. The mafic soil component is representative of widespread martian soils and is similar in compositi...

“Jake_M,” the first rock analyzed by the Alpha Particle X-ray Spectrometer instrument on the Curiosity rover, differs substantially in chemical composition from other known martian igneous rocks: It is alkaline (textgreater15% normative nepheline) and relatively fractionated. Jake_M is compositionally similar to terrestrial mugearites, a rock type...

Mars' Atmosphere from Curiosity The Sample Analysis at Mars (SAM) instrument on the Curiosity rover that landed on Mars in August last year is designed to study the chemical and isotopic composition of the martian atmosphere. Mahaffy et al. (p. 263 ) present volume-mixing ratios of Mars' five major atmospheric constituents (CO 2 , Ar, N 2 , O 2 , a...

Observations by the Mars Science Laboratory Mast Camera (Mastcam) in Gale crater reveal isolated outcrops of cemented pebbles (2 to 40 millimeters in diameter) and sand grains with textures typical of fluvial sedimentary conglomerates. Rounded pebbles in the conglomerates indicate substantial fluvial abrasion. ChemCam emission spectra at one outcro...

Introduction: The MSL Alpha-Particle-X-ray-Spectrometer(APXS) is the third generation of chemical in-situ instruments of its kind onboard a NASA Mars rover. We report here initial results during the first 102 sols at Gale Crater and discuss post landing performance and calibration compared to the laboratory. Operational improvements compared to the...

Sedimentary rocks examined by the Curiosity rover at Yellowknife Bay, Mars, were derived from sources that evolved from approximately average Martian crustal composition to one influenced by alkaline basalts. No evidence of chemical weathering is preserved indicating arid, possibly cold, paleoclimates and rapid erosion/deposition. Absence of predic...