0000000000178786
AUTHOR
L. A. Soderblom
Overview of the Spirit Mars Exploration Rover Mission to Gusev Crater: Landing site to Backstay Rock in the Columbia Hills
Spirit landed on the floor of Gusev Crater and conducted initial operations on soil covered, rock-strewn cratered plains underlain by olivine-bearing basalts. Plains surface rocks are covered by wind-blown dust and show evidence for surface enrichment of soluble species as vein and void-filling materials and coatings. The surface enrichment is the result of a minor amount of transport and deposition by aqueous processes. Layered granular deposits were discovered in the Columbia Hills, with outcrops that tend to dip conformably with the topography. The granular rocks are interpreted to be volcanic ash and/or impact ejecta deposits that have been modified by aqueous fluids during and/or after…
In situ evidence for an ancient aqueous environment at Meridiani Planum, Mars.
Sedimentary rocks at Eagle crater in Meridiani Planum are composed of fine-grained siliciclastic materials derived from weathering of basaltic rocks, sulfate minerals (including magnesium sulfate and jarosite) that constitute several tens of percent of the rock by weight, and hematite. Cross-stratification observed in rock outcrops indicates eolian and aqueous transport. Diagenetic features include hematite-rich concretions and crystal-mold vugs. We interpret the rocks to be a mixture of chemical and siliciclastic sediments with a complex diagenetic history. The environmental conditions that they record include episodic inundation by shallow surface water, evaporation, and desiccation. The …
The Spirit Rover's Athena science investigation at Gusev Crater, Mars.
The Mars Exploration Rover Spirit and its Athena science payload have been used to investigate a landing site in Gusev crater. Gusev is hypothesized to be the site of a former lake, but no clear evidence for lacustrine sedimentation has been found to date. Instead, the dominant lithology is basalt, and the dominant geologic processes are impact events and eolian transport. Many rocks exhibit coatings and other characteristics that may be evidence for minor aqueous alteration. Any lacustrine sediments that may exist at this location within Gusev apparently have been buried by lavas that have undergone subsequent impact disruption.
Soils of Eagle crater and Meridiani Planum at the Opportunity Rover landing site.
The soils at the Opportunity site are fine-grained basaltic sands mixed with dust and sulfate-rich outcrop debris. Hematite is concentrated in spherules eroded from the strata. Ongoing saltation exhumes the spherules and their fragments, concentrating them at the surface. Spherules emerge from soils coated, perhaps from subsurface cementation, by salts. Two types of vesicular clasts may represent basaltic sand sources. Eolian ripples, armored by well-sorted hematite-rich grains, pervade Meridiani Planum. The thickness of the soil on the plain is estimated to be about a meter. The flatness and thin cover suggest that the plain may represent the original sedimentary surface.
Overview of the Opportunity Mars Exploration Rover Mission to Meridiani Planum: Eagle Crater to Purgatory Ripple
The Mars Exploration Rover Opportunity touched down at Meridiani Planum in January 2004 and since then has been conducting observations with the Athena science payload. The rover has traversed more than 5 km, carrying out the first outcrop-scale investigation of sedimentary rocks on Mars. The rocks of Meridiani Planum are sandstones formed by eolian and aqueous reworking of sand grains that are composed of mixed fine-grained siliciclastics and sulfates. The siliciclastic fraction was produced by chemical alteration of a precursor basalt. The sulfates are dominantly Mg-sulfates and also include Ca-sulfates and jarosite. The stratigraphic section observed to date is dominated by eolian bedfor…
An integrated view of the chemistry and mineralogy of martian soils
The mineralogical and elemental compositions of the martian soil are indicators of chemical and physical weathering processes. Using data from the Mars Exploration Rovers, we show that bright dust deposits on opposite sides of the planet are part of a global unit and not dominated by the composition of local rocks. Dark soil deposits at both sites have similar basaltic mineralogies, and could reflect either a global component or the general similarity in the compositions of the rocks from which they were derived. Increased levels of bromine are consistent with mobilization of soluble salts by thin films of liquid water, but the presence of olivine in analysed soil samples indicates that the…
Water alteration of rocks and soils on Mars at the Spirit rover site in Gusev crater
The cover shows part of the Larry's Lookout panorama, seen from the Mars Exploration Rover (MER) Spirit during its drive up Husband Hill: the summit is about 200 metres from the rover. Six papers this week report in detail on the MER mission. An Analysis compares predictions used to select a landing site with the conditions actually encountered. This ‘ground truth’ will be invaluable for interpreting future remote-sensing data. Surface chemistry suggests that the upper layer of soil may contain 1% meteoritic material. MER provides a unique glimpse of solar transits of the moons Phobos and Deimos. Rover Opportunity examined wind-related processes, and spectroscopy indicates a dry origin for …
Pyroclastic Activity at Home Plate in Gusev Crater, Mars
Home Plate is a layered plateau in Gusev crater on Mars. It is composed of clastic rocks of moderately altered alkali basalt composition, enriched in some highly volatile elements. A coarsegrained lower unit lies under a finer-grained upper unit. Textural observations indicate that the lower strata were emplaced in an explosive event, and geochemical considerations favor an explosive volcanic origin over an impact origin. The lower unit likely represents accumulation of pyroclastic materials, whereas the upper unit may represent eolian reworking of the same pyroclastic materials.