Allan Treiman

Universities Space Research Association

Venus' surface and interior dynamics remain largely unconstrained, due in great part to the major obstacles to exploration imposed by its 470°C, 90 bar surface conditions and its thick, opaque atmosphere. Flyby and orbiter‐based thermal emission data provide opportunities to characterize the surface composition of Venus. However, robust interpretat...

Phosphorus is an essential component for life, and in-situ identification of phosphate minerals that formed in aqueous conditions directly contributes toward one of the main goals of the Mars 2020 Perseverance rover: to seek signs of ancient habitable environments. In Jezero crater, proximity science analyses within a conglomerate outcrop, “Onahu”...

The Perseverance rover has collected seven oriented samples of sedimentary rocks, all likely older than the oldest signs of widespread life on Earth, at the exposed base of the western fan in Jezero crater, Mars. The samples include a sulfate‐ and clay‐bearing mudstone and sandstone, a fluvial sandstone from a stratigraphically low position at the...

Gypsum is a common mineral at Gale crater on Mars, currently being explored by the Mars Science Laboratory (MSL) rover, Curiosity. In this paper, we summarize the associations of gypsum with other sulfate minerals (bassanite, anhydrite, jarosite, starkeyite, and kieserite) from the lowest levels of the crater’s northern moat zone (Aeolis Palus) up...

This study presents mineral composition estimates of rock and sediment samples analyzed with the CheMin X-ray diffraction instrument on board the NASA Mars Science Laboratory rover, Curiosity, in Gale crater, Mars. Mineral composition is estimated using crystal-chemically derived algorithms applied to X-ray diffraction data, specifically unit-cell...

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...

For more than a decade, the CheMin X-ray diffraction instrument on the Mars Science Laboratory rover, Curiosity, has been returning definitive and quantitative mineralogical and mineral–chemistry data from ~3.5-billion-year-old (Ga) sediments in Gale crater, Mars. To date, 40 drilled rock samples and three scooped soil samples have been analyzed du...

Plain Language Summary Images and compositional data of Mars rocks taken by the Mars 2020 Perseverance Rover at Hogwallow Flats and Yori Pass in Jezero crater show an abundance of sulfate minerals. The goal of this study was to describe the characteristics of these rocks with close‐up views of places where these rocks were abraded to expose fresh r...

A centimeter-sized fragment of dunite, the first recognized fragment of Moon mantle material, has been discovered in the lunar highlands breccia meteorite Northwest Africa (NWA) 11421. The dunite consists of 95% olivine (Fo83), with low-Ca and high-Ca pyroxenes, plagioclase, and chrome spinel. Mineral compositions vary little across the clast and a...

We have studied the properties of the Nili Fossae olivine lithology from orbital data and in situ by the Mars 2020 rover at the Séítah unit in Jezero crater. We used the geochemistry collected by the rover’s instruments to calculate the viscosity and relative flow distance of the Séítah unit. Based on the low viscosity and distribution of the unit...

For the first time on Mars, the crystalline magnesium‐sulfate mineral starkeyite (MgSO4‧4H2O) was definitively identified using the CheMin X‐ray diffraction instrument at Gale crater. At the Canaima drill site, starkeyite along with amorphous MgSO4‧nH2O are among the “polyhydrated Mg‐sulfates” interpreted in orbital reflectance spectra. Mg‐sulfates...

A systematic survey of 161 known and postulated minerals originating on Mars points to 20 different mineral‐forming processes (paragenetic modes), which are a subset of formation modes observed on Earth. The earliest martian minerals, as on Earth, were primary phases from mafic igneous rocks and their ultramafic cumulates. Subsequent primary igneou...

The MSL Curiosity rover investigated dark, Mn-P-enriched nodules in shallow lacustrine/fluvial sediments at the Groken site in Glen Torridon, Gale Crater, Mars. Applying all relevant information from the rover, the nodules are interpreted as pseudomorphs after original crystals of vivianite, (Fe2+,Mn2+)3(PO4)2·8H2O, that cemented the sediment soon...

The Máaz formation consists of the first lithologies in Jezero crater analyzed by the Mars 2020 Perseverance rover. This formation, investigated from Sols (Martian days) 1 to 201 and from Sols 343 to 382, overlies the Séítah formation (previously described as an olivine‐rich cumulate) and was initially suggested to represent an igneous crater floor...

We have studied the observed properties of the Nili Fossae olivine-phyllosilicate-carbonate lithology from orbital data and in situ by the Mars 2020 rover at the Séítah unit in Jezero crater, including: 1) composition 2) grain size 3) inferred viscosity (calculated based on geochemistry collected by SuperCam (Wiens et al., 2022)). Based on the low...

On ~sol 370 of the Perseverance rover mission, the Mars 2020 Science Team completed its investigation of igneous units of the Jezero crater floor [1] and directed Perseverance to drive towards the topographic scarp that marks the interface between the crater floor and Jezero’s western delta. The “Delta Front Campaign” consisted of close-up investig...

The Mars Science Laboratory rover, Curiosity, explored the clay mineral‐bearing Glen Torridon region for 1 Martian year between January 2019 and January 2021, including a short campaign onto the Greenheugh pediment. The Glen Torridon campaign sought to characterize the geology of the area, seek evidence of habitable environments, and document the o...

We analyze spatially pervasive, light‐toned “halos” associated with fractures in a sedimentary unit (Stimson) of Gale crater, Mars, and report a similar network of halos discovered in a separate geologic group (Bradbury). Through a dedicated active neutron measurement campaign, we provide independent confirmation of the water‐rich nature of these f...

Radar images of Venus’s tallest mountain range, Maxwell Montes, show a sharp increase in radar reflectivity, a “snow line,” at high elevation. This snow line has been inferred to represent a single common elevation (and thus temperature and pressure) above which metallic or semimetal compounds are present on the surface, either as direct precipitat...

Collocated crystal sizes and mineral identities are critical for interpreting textural relationships in rocks and testing geological hypotheses, but it has been previously impossible to unambiguously constrain these properties using in situ instruments on Mars rovers. Here, we demonstrate that diffracted and fluoresced x-rays detected by the PIXL i...

The Glen Torridon (GT) region in Gale crater, Mars is a region with strong clay mineral signatures inferred from orbital spectroscopy. The CheMin X‐ray diffraction (XRD) instrument onboard the Mars Science Laboratory rover, Curiosity, measured some of the highest clay mineral abundances to date within GT, complementing the orbital detections. GT ma...

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 presence and distribution of hydrogen‐bearing materials in meteorites are important constraints on processes in the early solar system, and the delivery of volatile constituents to growing planets. Here, we show that coordinated neutron and X‐ray computed tomography, NXCT, can reveal the presence and distributions of hydrogen‐bearing materials...

The Perseverance rover landed in Jezero crater, Mars, to investigate ancient lake and river deposits. We report observations of the crater floor, below the crater’s sedimentary delta, finding the floor consists of igneous rocks altered by water. The lowest exposed unit, informally named Séítah, is a coarsely crystalline olivine-rich rock, which acc...

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...

MS‐MU‐012, a 15.5 g clast from the Almahata Sitta polymict ureilite, is the first known plagioclase‐bearing main group ureilite. It is a coarse‐grained (up to 4 mm), equilibrated assemblage of 52% olivine (Fo 88), 13% orthopyroxene (Mg# 89.2, Wo 4.5), 11% augite (Mg# 90.2, Wo 37.3), and 14% plagioclase (An 68), plus minor metal and sulfide. The pla...

We examine the observed properties of the Nili Fossae olivine-clay-carbonate lithology from orbital data and in situ by the Mars 2020 rover at the S\'e\'itah unit in Jezero crater, including: 1) composition (Liu, 2022) 2) grain size (Tice, 2022) 3) inferred viscosity (calculated based on geochemistry collected by SuperCam (Wiens, 2022)). Based on t...

Characterizing the surface of Venus has been complicated by its thick atmosphere and caustic surface conditions (~470 °C, 90 bars). Several approaches, including the collection of spectral data, thermodynamic modelling, lander missions, and surface weathering laboratory experiments have progressed our view of what lies at the surface. However, surf...

The Perseverance rover landed on the floor of Jezero crater on 18 February 2021. The landing site, named “Octavia E. Butler” is located ~2.2 km from the SE-facing erosional scarp of the western fan deposits, which are of strong interest for the mission [1-2]. Images obtained using the Mastcam-Z camera and the Remote Micro-Imager (RMI) of the SuperC...

Low-grade metamorphic hydrous minerals and carbonates occur in various settings on Mars and in Martian meteorites. We present constraints on the stability of prehnite, zeolites, serpentine, and carbonates by modeling the influence of H2O-CO2 fluids during low-grade metamorphism in the Martian crust using compositions of a Martian basalt and an ultr...

Perseverance images of a delta on Mars The Perseverance rover landed in Jezero crater, Mars, in February 2021. Earlier orbital images showed that the crater contains an ancient river delta that was deposited by water flowing into a lake billions of years ago. Mangold et al . analyzed rover images taken shortly after landing that show distant cliff...

Curiosity, the Mars Science Laboratory (MSL) rover, landed on Mars in August 2012 to investigate the ~3.5-billion-year-old (Ga) fluvio-lacustrine sedimentary deposits of Aeolis Mons (informally known as Mount Sharp) and the surrounding plains (Aeolis Palus) in Gale crater. After nearly nine years, Curiosity has traversed over 25 km, and the Chemist...

Aerosol phase elements such as phosphorus (P), sulfur (S), and metals including iron (Fe) are essential nutrients that could help sustain potential biodiversity in the cloud deck of Venus. While the presence of S and Fe in the venusian cloud deck has been broadly discussed (Zasova et al., 1981; Krasnopolsky, 2012, 2013, 2016, 2017; Markiewicz et al...

Modified clay minerals on Mars Sedimentary rocks exposed in Gale crater on Mars contain extensive clay minerals. Bristow et al. analyzed drill samples collected by the Curiosity rover as it climbed up sedimentary layers in the crater. They found evidence of past reactions with liquid water and sulfate brines, which could have percolated through the...

The martian meteorite ALH 84001 formed before ∼4.0 Ga, so it could have preserved information about habitability on early Mars and habitability since then. ALH 84001 is particularly important as it contains carbonate (and other) minerals that were deposited by liquid water, raising the chance that they may have formed in a habitable environment. De...

Carbonaceous chondrite meteorites record the earliest stages of Solar System geological activities and provide insight into their parent bodies’ histories. Some carbonaceous chondrites are volumetrically dominated by hydrated minerals, providing evidence for low-temperature, low-pressure aqueous alteration¹. Others are dominated by anhydrous minera...

Light emitted from Venus’s surface can be viewed through spectral “windows” in its atmosphere, in the near-infrared (NIR) around 1000 nanometer (nm) wavelengths. The NIR emissivity of Venus’s surface can constrain rock types and their weathering state; emissivities can be measured directly or calculated from reflectances. We measured the reflectanc...

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...

A Correction to this paper has been published: https://doi.org/10.1007/s11214-021-00801-2

Planetary Instrument for X-ray Lithochemistry (PIXL) is a micro-focus X-ray fluorescence spectrometer mounted on the robotic arm of NASA’s Perseverance rover. PIXL will acquire high spatial resolution observations of rock and soil chemistry, rapidly analyzing the elemental chemistry of a target surface. In 10 seconds, PIXL can use its powerful 120...

Bulk chemical composition is a fundamental property of a planetary material, rock or regolith, and can be used to constrain the properties and history of a material, and by extension its parent body, including its potential for habitability. Here, we investigate how uncertainties in bulk major element analyses can affect inferences derived from tho...

Vera Rubin ridge (VRR) is an erosion‐resistant feature on the northwestern slope of Mount Sharp in Gale crater, Mars, and orbital visible/shortwave infrared measurements indicate it contains red hematite. The Mars Science Laboratory Curiosity rover performed an extensive campaign on VRR to study its mineralogy, geochemistry, and sedimentology to de...

Hydrothermal high sanidine and specular hematite are found within ferric‐rich and gray‐colored cemented basaltic breccia occurring within horizontal, weathering‐resistant strata exposed in an erosional gully of the Pu'u Poliahu cinder cone in the summit region of Maunakea volcano (Hawai'i). The cone was extensively altered by hydrothermal, acid‐sul...

The Curiosity rover's exploration of rocks and soils in Gale crater has provided diverse geochemical and mineralogical data sets, underscoring the complex geological history of the region. We report the crystalline, clay mineral, and amorphous phase distributions of four Gale crater rocks from an 80‐m stratigraphic interval. The mineralogy of the f...

Alteration of basalt on the surface of Venus should be dominated by nanophase hematite and sulfate coatings, but the timescale of oxidation and how that affects spectroscopic measurements has not been extensively studied. The oxidation rate and the effect on reflectance spectroscopy are needed to constrain the age of lava flows with high emissivity...

Rock alteration processes on Venus are still poorly understood due to the limited geochemical data on surface rocks and uncertainties in atmospheric compositions. We use phase equilibria calculations to constrain mineral stabilities at Venus surface conditions for different rock and gas compositions resulting in the chemical system SiO2-TiO2-Al2O3-...

The Mars Science Laboratory Curiosity rover arrived at Mars in August 2012 with a primary goal of characterizing the habitability of ancient and modern environments. Curiosity was sent to Gale crater to study a sequence of ∼3.5 Ga old sedimentary rocks that, based on orbital visible and near- to short-wave infrared reflectance spectra, contain seco...

At least some of Venus’ lava flows are thought to be <2.5 million years old based on visible to near-infrared (VNIR) emissivity measured by the Venus Express spacecraft. However, the exact ages of these flows are poorly constrained because the rate at which olivine alters at Venus surface conditions, and how that alteration affects VNIR spectra, re...