David J. Des Marais
A5003896741- Planetary Science and Exploration
- Astro and Planetary Science
- Paleontology and Stratigraphy of Fossils
- Geology and Paleoclimatology Research
- Microbial Community Ecology and Physiology
- Isotope Analysis in Ecology
- Methane Hydrates and Related Phenomena
- Space Science and Extraterrestrial Life
- Space Exploration and Technology
- Marine and coastal ecosystems
- Hydrocarbon exploration and reservoir analysis
- Atmospheric and Environmental Gas Dynamics
- Geological and Geochemical Analysis
- Algal biology and biofuel production
- Geochemistry and Geologic Mapping
- Polar Research and Ecology
- Marine Biology and Ecology Research
- Aquatic Ecosystems and Phytoplankton Dynamics
- Origins and Evolution of Life
- Genomics and Phylogenetic Studies
- Metabolomics and Mass Spectrometry Studies
- Biocrusts and Microbial Ecology
- Radioactive element chemistry and processing
- Geochemistry and Elemental Analysis
- Scientific Computing and Data Management
Ames Research Center
2015-2024
Chesapeake Bay Program
2020
National Aeronautics and Space Administration
1987-2013
NASA Astrobiology Institute
2003-2008
Search for Extraterrestrial Intelligence
2004-2008
Cornell University
2004-2008
Arizona State University
2008
University of Guelph
2008
Johnson Space Center
2008
Johns Hopkins University Applied Physics Laboratory
2008
Spirit landed on the floor of Gusev Crater and conducted initial operations soil‐covered, rock‐strewn cratered plains underlain by olivine‐bearing basalts. Plains surface rocks are covered wind‐blown dust show evidence for enrichment soluble species as vein void‐filling materials coatings. The is result a minor amount transport deposition aqueous processes. Layered granular deposits were discovered in Columbia Hills, with outcrops that tend to dip conformably topography. interpreted be...
The Noachian terrain west of the Isidis basin hosts a diverse collection alteration minerals in rocks comprising varied geomorphic units within 100,000 km 2 region and near Nili Fossae. Prior investigations this by Observatoire pour l'Minéralogie, l'Eau, les Glaces, et l'Activité (OMEGA) instrument on Mars Express revealed large exposures both mafic iron magnesium phyllosilicates stratigraphic context. Expanding discoveries OMEGA, Compact Reconnaissance Imaging Spectrometer for (CRISM)...
Geochemical models for Mars predict carbonate formation during aqueous alteration. Carbonate-bearing rocks had not previously been detected on Mars' surface, but Reconnaissance Orbiter mapping reveals a regional rock layer with near-infrared spectral characteristics that are consistent the presence of magnesium in Nili Fossae region. The is closely associated both phyllosilicate-bearing and olivine-rich units probably formed Noachian or early Hesperian era from alteration olivine by either...
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, sulfides, amorphous material, trioctahedral smectites. smectite has basal spacing of ~10 angstroms, indicating little interlayer hydration. Cumberland both ~13.2 angstroms. larger suggests a partially chloritized magnesium facilitating H2O retention. Basaltic minerals...
Martian aqueous mineral deposits have been examined and characterized using data acquired during Mars Reconnaissance Orbiter's (MRO) primary science phase, including Compact Imaging Spectrometer for hyperspectral images covering the 0.4–3.9 μ m wavelength range, coordinated with higher–spatial resolution HiRISE Context Imager images. MRO's new high‐resolution measurements, combined earlier from Thermal Emission Spectrometer; System; Observatoire pour la Minéralogie, L'Eau, les Glaces et...
The Mars Exploration Rover Opportunity has investigated the landing site in Eagle crater and nearby plains within Meridiani Planum. soils consist of fine-grained basaltic sand a surface lag hematite-rich spherules, spherule fragments, other granules. Wind ripples are common. Underlying thin soil layer, exposed small impact craters troughs, flat-lying sedimentary rocks. These rocks finely laminated, rich sulfur, contain abundant sulfate salts. Small-scale cross-lamination some locations...
The major goals of NASA's Terrestrial Planet Finder (TPF) and the European Space Agency's Darwin missions are to detect terrestrial-sized extrasolar planets directly seek spectroscopic evidence habitable conditions life. Here we recommend wavelength ranges spectral features for these missions. We assess known molecular band Earth, Venus, Mars in context putative analogs. preferred 7-25 microns mid-IR 0.5 approximately 1.1 visible near-IR. Detection O2 or its photolytic product O3 merits...
Abstract The Sample Analysis at Mars (SAM) instrument on board the Science Laboratory Curiosity rover is designed to conduct inorganic and organic chemical analyses of atmosphere surface regolith rocks help evaluate past present habitability potential Gale Crater. Central this task development an inventory any molecules elucidate processes associated with their origin, diagenesis, concentration, long‐term preservation. This will guide future search for biosignatures. Here we report...
Mineral deposits on the martian surface can elucidate ancient environmental conditions planet. Opaline silica (as much as 91 weight percent SiO2) have been found in association with volcanic materials by Mars rover Spirit. The are present both light-toned soils and bedrock. We interpret these to formed under hydrothermal therefore be strong indicators of a former aqueous environment. This discovery is important for understanding past habitability because environments Earth support thriving...
Measurements of bacterial sulfate reduction and dissolved oxygen (O2) in hypersaline mats from Baja California, Mexico, revealed that occurred consistently within the well-oxygenated photosynthetic zone mats. This evidence dissimilatory can occur presence O2 challenges conventional view is a strictly anaerobic process. At constant temperature, rates oxygenated during daytime were similar to anoxic at night: thus, 24-hour cycle, variations light have little effect on these
H 2 O, CO , SO O S, HCl, chlorinated hydrocarbons, NO, and other trace gases were evolved during pyrolysis of two mudstone samples acquired by the Curiosity rover at Yellowknife Bay within Gale crater, Mars. O/OH-bearing phases included 2:1 phyllosilicate(s), bassanite, akaganeite, amorphous materials. Thermal decomposition carbonates combustion organic materials are candidate sources for . Concurrent evolution hydrocarbons suggests presence oxychlorine phase(s). Sulfides likely...
The NASA Astrobiology Roadmap provides guidance for research and technology development across the enterprises that encompass space, Earth, biological sciences. ongoing of astrobiology roadmaps embodies contributions diverse scientists technologists from government, universities, private institutions. addresses three basic questions: how does life begin evolve, exist elsewhere in universe, what is future on Earth beyond? Seven Science Goals outline following key domains investigation:...
The Rocknest aeolian deposit is similar to features analyzed by the Mars Exploration Rovers (MERs) Spirit and Opportunity. fraction of sand <150 micrometers in size contains ~55% crystalline material consistent with a basaltic heritage ~45% x-ray amorphous material. component iron-rich silicon-poor host volatiles (water, oxygen, sulfur dioxide, carbon chlorine) detected Sample Analysis at instrument fine-grained nanophase oxide first described from soils MERs. similarity between materials...
The Mars Science Laboratory Curiosity rover has been traversing strata at the base of Aeolis Mons (informally known as Mount Sharp) since September 2014. Murray formation makes up lowest exposed Sharp group and is composed primarily finely laminated lacustrine mudstone intercalated with rare crossbedded sandstone that prodeltaic or fluvial in origin. We report on first three drilled samples from formation, measured Pahrump Hills section. Rietveld refinements FULLPAT full pattern fitting...
Sedimentary rocks examined by the Curiosity rover at Yellowknife Bay, Mars, were derived from sources that evolved an approximately average martian crustal composition to one influenced alkaline basalts. No evidence of chemical weathering is preserved, indicating arid, possibly cold, paleoclimates and rapid erosion deposition. The absence predicted geochemical variations indicates magnetite phyllosilicates formed diagenesis under low-temperature, circumneutral pH, rock-dominated aqueous...
Significance Tridymite, a SiO 2 mineral that crystallizes at low pressures and high temperatures (>870 °C) from high-SiO materials, was detected concentrations in sedimentary mudstone Gale crater, Mars. Mineralogy abundance were determined by X-ray diffraction using the Chemistry instrument on Mars Science Laboratory rover Curiosity . Terrestrial tridymite is commonly associated with silicic volcanism where high-silica magmas prevail, so this occurrence first situ mineralogical evidence...
Clay minerals found in Gale crater, Mars, record surficial chemical weathering and changing conditions an ancient lake.
Life began early in Earth's history, but it was the emergence of photosynthesis that allowed its proliferation across planet, because freed life from sole dependence on abiotic chemical sources reducing power. Des Marais discusses recent geological and molecular biological evidence, such as paper by Xiong et al., emerged at least 2,800 million years ago.
Petrographic and geochemical analyses of travertine-depositing hot springs at Angel Terrace, Mammoth Hot Springs, Yellowstone National Park, have been used to define five depositional facies along the spring drainage system. Spring waters are expelled in vent 71 73 degrees C precipitate mounded travertine composed aragonite needle botryoids. The apron channel (43-72 C) is floored by hollow tubes botryoids that encrust sulfide-oxidizing Aquificales bacteria. pond (30-62 varies composition...