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Bell JF, Lemmon MT, Duxbury TC, Hubbard MYH, Wolff MJ, Squyres SW, Craig L, Ludwinski JM. Solar eclipses of Phobos and Deimos observed from the surface of Mars. Nature 2005; 436:55-7. [PMID: 16001060 DOI: 10.1038/nature03437] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2004] [Accepted: 01/31/2005] [Indexed: 11/08/2022]
Abstract
The small martian satellites Phobos and Deimos orbit in synchronous rotation with inclinations of only 0.01 degrees and 0.92 degrees , respectively, relative to the planet's equatorial plane. Thus, an observer at near-equatorial latitudes on Mars could occasionally observe solar eclipses by these satellites (see ref. 1, for example). Because the apparent angular diameter of the satellites is much smaller than that of the Sun, however, such events are more appropriately referred to as transits. Transit data can be used for correcting and refining the orbital ephemerides of the moons. For example, Phobos is known to exhibit a secular acceleration that is caused by tidal dissipation within Mars. Long-term, accurate measurements are needed to refine the magnitude and origin of this dissipation within the martian interior as well as to refine the predicted orbital evolution of both satellites. Here we present observations of six transits of Phobos and Deimos across the solar disk from cameras on Mars aboard the Mars Exploration Rovers Spirit and Opportunity. These are the first direct imaging observations of satellites transiting the Sun from the surface of another planet.
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Golombek MP, Arvidson RE, Bell JF, Christensen PR, Crisp JA, Crumpler LS, Ehlmann BL, Fergason RL, Grant JA, Greeley R, Haldemann AFC, Kass DM, Parker TJ, Schofield JT, Squyres SW, Zurek RW. Assessment of Mars Exploration Rover landing site predictions. Nature 2005; 436:44-8. [PMID: 16001058 DOI: 10.1038/nature03600] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Comprehensive analyses of remote sensing data during the three-year effort to select the Mars Exploration Rover landing sites at Gusev crater and at Meridiani Planum correctly predicted the atmospheric density profile during entry and descent and the safe and trafficable surfaces explored by the two rovers. The Gusev crater site was correctly predicted to be a low-relief surface that was less rocky than the Viking landing sites but comparably dusty. A dark, low-albedo, flat plain composed of basaltic sand and haematite with very few rocks was expected and found at Meridiani Planum. These results argue that future efforts to select safe landing sites based on existing and acquired remote sensing data will be successful. In contrast, geological interpretations of the sites based on remote sensing data were less certain and less successful, which emphasizes the inherent ambiguities in understanding surface geology from remotely sensed data and the uncertainty in predicting exactly what materials will be available for study at a landing site.
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Squyres SW, Arvidson RE, Bell JF, Brückner J, Cabrol NA, Calvin W, Carr MH, Christensen PR, Clark BC, Crumpler L, Marais DJD, d'Uston C, Economou T, Farmer J, Farrand W, Folkner W, Golombek M, Gorevan S, Grant JA, Greeley R, Grotzinger J, Haskin L, Herkenhoff KE, Hviid S, Johnson J, Klingelhöfer G, Knoll AH, Landis G, Lemmon M, Li R, Madsen MB, Malin MC, McLennan SM, McSween HY, Ming DW, Moersch J, Morris RV, Parker T, Rice JW, Richter L, Rieder R, Sims M, Smith M, Smith P, Soderblom LA, Sullivan R, Wänke H, Wdowiak T, Wolff M, Yen A. The Opportunity Rover's Athena science investigation at Meridiani Planum, Mars. Science 2004; 306:1698-703. [PMID: 15576602 DOI: 10.1126/science.1106171] [Citation(s) in RCA: 130] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The Mars Exploration Rover Opportunity has investigated the landing site in Eagle crater and the nearby plains within Meridiani Planum. The soils consist of fine-grained basaltic sand and a surface lag of hematite-rich spherules, spherule fragments, and other granules. Wind ripples are common. Underlying the thin soil layer, and exposed within small impact craters and troughs, are flat-lying sedimentary rocks. These rocks are finely laminated, are rich in sulfur, and contain abundant sulfate salts. Small-scale cross-lamination in some locations provides evidence for deposition in flowing liquid water. We interpret the rocks to be a mixture of chemical and siliciclastic sediments formed by episodic inundation by shallow surface water, followed by evaporation, exposure, and desiccation. Hematite-rich spherules are embedded in the rock and eroding from them. We interpret these spherules to be concretions formed by postdepositional diagenesis, again involving liquid water.
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Lemmon MT, Wolff MJ, Smith MD, Clancy RT, Banfield D, Landis GA, Ghosh A, Smith PH, Spanovich N, Whitney B, Whelley P, Greeley R, Thompson S, Bell JF, Squyres SW. Atmospheric imaging results from the Mars exploration rovers: Spirit and Opportunity. Science 2004; 306:1753-6. [PMID: 15576613 DOI: 10.1126/science.1104474] [Citation(s) in RCA: 188] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
A visible atmospheric optical depth of 0.9 was measured by the Spirit rover at Gusev crater and by the Opportunity rover at Meridiani Planum. Optical depth decreased by about 0.6 to 0.7% per sol through both 90-sol primary missions. The vertical distribution of atmospheric dust at Gusev crater was consistent with uniform mixing, with a measured scale height of 11.56 +/- 0.62 kilometers. The dust's cross section weighted mean radius was 1.47 +/- 0.21 micrometers (mm) at Gusev and 1.52 +/- 0.18 mm at Meridiani. Comparison of visible optical depths with 9-mm optical depths shows a visible-to-infrared optical depth ratio of 2.0 +/- 0.2 for comparison with previous monitoring of infrared optical depths.
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Arvidson RE, Anderson RC, Bartlett P, Bell JF, Christensen PR, Chu P, Davis K, Ehlmann BL, Golombek MP, Gorevan S, Guinness EA, Haldemann AFC, Herkenhoff KE, Landis G, Li R, Lindemann R, Ming DW, Myrick T, Parker T, Richter L, Seelos FP, Soderblom LA, Squyres SW, Sullivan RJ, Wilson J. Localization and physical property experiments conducted by Opportunity at Meridiani Planum. Science 2004; 306:1730-3. [PMID: 15576608 DOI: 10.1126/science.1104211] [Citation(s) in RCA: 117] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The location of the Opportunity landing site was determined to better than 10-m absolute accuracy from analyses of radio tracking data. We determined Rover locations during traverses with an error as small as several centimeters using engineering telemetry and overlapping images. Topographic profiles generated from rover data show that the plains are very smooth from meter- to centimeter-length scales, consistent with analyses of orbital observations. Solar cell output decreased because of the deposition of airborne dust on the panels. The lack of dust-covered surfaces on Meridiani Planum indicates that high velocity winds must remove this material on a continuing basis. The low mechanical strength of the evaporitic rocks as determined from grinding experiments, and the abundance of coarse-grained surface particles argue for differential erosion of Meridiani Planum.
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Bell JF, Squyres SW, Arvidson RE, Arneson HM, Bass D, Calvin W, Farrand WH, Goetz W, Golombek M, Greeley R, Grotzinger J, Guinness E, Hayes AG, Hubbard MYH, Herkenhoff KE, Johnson MJ, Johnson JR, Joseph J, Kinch KM, Lemmon MT, Li R, Madsen MB, Maki JN, Malin M, McCartney E, McLennan S, McSween HY, Ming DW, Morris RV, Dobrea EZN, Parker TJ, Proton J, Rice JW, Seelos F, Soderblom JM, Soderblom LA, Sohl-Dickstein JN, Sullivan RJ, Weitz CM, Wolff MJ. Pancam multispectral imaging results from the Opportunity Rover at Meridiani Planum. Science 2004; 306:1703-9. [PMID: 15576603 DOI: 10.1126/science.1105245] [Citation(s) in RCA: 115] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Panoramic Camera (Pancam) images from Meridiani Planum reveal a low-albedo, generally flat, and relatively rock-free surface. Within and around impact craters and fractures, laminated outcrop rocks with higher albedo are observed. Fine-grained materials include dark sand, bright ferric iron-rich dust, angular rock clasts, and millimeter-size spheroidal granules that are eroding out of the laminated rocks. Spectra of sand, clasts, and one dark plains rock are consistent with mafic silicates such as pyroxene and olivine. Spectra of both the spherules and the laminated outcrop materials indicate the presence of crystalline ferric oxides or oxyhydroxides. Atmospheric observations show a steady decline in dust opacity during the mission. Astronomical observations captured solar transits by Phobos and Deimos and time-lapse observations of sunsets.
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Rieder R, Gellert R, Anderson RC, Brückner J, Clark BC, Dreibus G, Economou T, Klingelhöfer G, Lugmair GW, Ming DW, Squyres SW, d'Uston C, Wänke H, Yen A, Zipfel J. Chemistry of rocks and soils at Meridiani Planum from the Alpha Particle X-ray Spectrometer. Science 2004; 306:1746-9. [PMID: 15576611 DOI: 10.1126/science.1104358] [Citation(s) in RCA: 314] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The Alpha Particle X-ray Spectrometer on the Opportunity rover determined major and minor elements of soils and rocks in Meridiani Planum. Chemical compositions differentiate between basaltic rocks, evaporite-rich rocks, basaltic soils, and hematite-rich soils. Although soils are compositionally similar to those at previous landing sites, differences in iron and some minor element concentrations signify the addition of local components. Rocky outcrops are rich in sulfur and variably enriched in bromine relative to chlorine. The interaction with water in the past is indicated by the chemical features in rocks and soils at this site.
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Squyres SW, Grotzinger JP, Arvidson RE, Bell JF, Calvin W, Christensen PR, Clark BC, Crisp JA, Farrand WH, Herkenhoff KE, Johnson JR, Klingelhöfer G, Knoll AH, McLennan SM, McSween HY, Morris RV, Rice JW, Rieder R, Soderblom LA. In situ evidence for an ancient aqueous environment at Meridiani Planum, Mars. Science 2004; 306:1709-14. [PMID: 15576604 DOI: 10.1126/science.1104559] [Citation(s) in RCA: 244] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
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 geologic record at Meridiani Planum suggests that conditions were suitable for biological activity for a period of time in martian history.
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Herkenhoff KE, Squyres SW, Arvidson R, Bass DS, Bell JF, Bertelsen P, Ehlmann BL, Farrand W, Gaddis L, Greeley R, Grotzinger J, Hayes AG, Hviid SF, Johnson JR, Jolliff B, Kinch KM, Knoll AH, Madsen MB, Maki JN, McLennan SM, McSween HY, Ming DW, Rice JW, Richter L, Sims M, Smith PH, Soderblom LA, Spanovich N, Sullivan R, Thompson S, Wdowiak T, Weitz C, Whelley P. Evidence from Opportunity's Microscopic Imager for water on Meridiani Planum. Science 2004; 306:1727-30. [PMID: 15576607 DOI: 10.1126/science.1105286] [Citation(s) in RCA: 118] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The Microscopic Imager on the Opportunity rover analyzed textures of soils and rocks at Meridiani Planum at a scale of 31 micrometers per pixel. The uppermost millimeter of some soils is weakly cemented, whereas other soils show little evidence of cohesion. Rock outcrops are laminated on a millimeter scale; image mosaics of cross-stratification suggest that some sediments were deposited by flowing water. Vugs in some outcrop faces are probably molds formed by dissolution of relatively soluble minerals during diagenesis. Microscopic images support the hypothesis that hematite-rich spherules observed in outcrops and soils also formed diagenetically as concretions.
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Soderblom LA, Anderson RC, Arvidson RE, Bell JF, Cabrol NA, Calvin W, Christensen PR, Clark BC, Economou T, Ehlmann BL, Farrand WH, Fike D, Gellert R, Glotch TD, Golombek MP, Greeley R, Grotzinger JP, Herkenhoff KE, Jerolmack DJ, Johnson JR, Jolliff B, Klingelhöfer G, Knoll AH, Learner ZA, Li R, Malin MC, McLennan SM, McSween HY, Ming DW, Morris RV, Rice JW, Richter L, Rieder R, Rodionov D, Schröder C, Seelos FP, Soderblom JM, Squyres SW, Sullivan R, Watters WA, Weitz CM, Wyatt MB, Yen A, Zipfel J. Soils of Eagle Crater and Meridiani Planum at the Opportunity Rover Landing Site. Science 2004; 306:1723-6. [PMID: 15576606 DOI: 10.1126/science.1105127] [Citation(s) in RCA: 138] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
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.
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Klingelhöfer G, Morris RV, Bernhardt B, Schröder C, Rodionov DS, de Souza PA, Yen A, Gellert R, Evlanov EN, Zubkov B, Foh J, Bonnes U, Kankeleit E, Gütlich P, Ming DW, Renz F, Wdowiak T, Squyres SW, Arvidson RE. Jarosite and Hematite at Meridiani Planum from Opportunity's Mössbauer Spectrometer. Science 2004; 306:1740-5. [PMID: 15576610 DOI: 10.1126/science.1104653] [Citation(s) in RCA: 193] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Mossbauer spectra measured by the Opportunity rover revealed four mineralogical components in Meridiani Planum at Eagle crater: jarosite- and hematite-rich outcrop, hematite-rich soil, olivine-bearing basaltic soil, and a pyroxene-bearing basaltic rock (Bounce rock). Spherules, interpreted to be concretions, are hematite-rich and dispersed throughout the outcrop. Hematitic soils both within and outside Eagle crater are dominated by spherules and their fragments. Olivine-bearing basaltic soil is present throughout the region. Bounce rock is probably an impact erratic. Because jarosite is a hydroxide sulfate mineral, its presence at Meridiani Planum is mineralogical evidence for aqueous processes on Mars, probably under acid-sulfate conditions.
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Christensen PR, Wyatt MB, Glotch TD, Rogers AD, Anwar S, Arvidson RE, Bandfield JL, Blaney DL, Budney C, Calvin WM, Fallacaro A, Fergason RL, Gorelick N, Graff TG, Hamilton VE, Hayes AG, Johnson JR, Knudson AT, McSween HY, Mehall GL, Mehall LK, Moersch JE, Morris RV, Smith MD, Squyres SW, Ruff SW, Wolff MJ. Mineralogy at Meridiani Planum from the Mini-TES Experiment on the Opportunity Rover. Science 2004; 306:1733-9. [PMID: 15576609 DOI: 10.1126/science.1104909] [Citation(s) in RCA: 114] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The Miniature Thermal Emission Spectrometer (Mini-TES) on Opportunity investigated the mineral abundances and compositions of outcrops, rocks, and soils at Meridiani Planum. Coarse crystalline hematite and olivine-rich basaltic sands were observed as predicted from orbital TES spectroscopy. Outcrops of aqueous origin are composed of 15 to 35% by volume magnesium and calcium sulfates [a high-silica component modeled as a combination of glass, feldspar, and sheet silicates (approximately 20 to 30%)], and hematite; only minor jarosite is identified in Mini-TES spectra. Mini-TES spectra show only a hematite signature in the millimeter-sized spherules. Basaltic materials have more plagioclase than pyroxene, contain olivine, and are similar in inferred mineral composition to basalt mapped from orbit. Bounce rock is dominated by clinopyroxene and is close in inferred mineral composition to the basaltic martian meteorites. Bright wind streak material matches global dust. Waterlain rocks covered by unaltered basaltic sands suggest a change from an aqueous environment to one dominated by physical weathering.
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Squyres SW, Arvidson RE, Bell JF, Brückner J, Cabrol NA, Calvin W, Carr MH, Christensen PR, Clark BC, Crumpler L, Des Marais DJ, D'Uston C, Economou T, Farmer J, Farrand W, Folkner W, Golombek M, Gorevan S, Grant JA, Greeley R, Grotzinger J, Haskin L, Herkenhoff KE, Hviid S, Johnson J, Klingelhöfer G, Knoll A, Landis G, Lemmon M, Li R, Madsen MB, Malin MC, McLennan SM, McSween HY, Ming DW, Moersch J, Morris RV, Parker T, Rice JW, Richter L, Rieder R, Sims M, Smith M, Smith P, Soderblom LA, Sullivan R, Wänke H, Wdowiak T, Wolff M, Yen A. The Spirit Rover's Athena science investigation at Gusev Crater, Mars. SCIENCE (NEW YORK, N.Y.) 2004; 305:794-9. [PMID: 15297657 DOI: 10.1126/science.1100194] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
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.
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Arvidson RE, Anderson RC, Bartlett P, Bell JF, Blaney D, Christensen PR, Chu P, Crumpler L, Davis K, Ehlmann BL, Fergason R, Golombek MP, Gorevan S, Grant JA, Greeley R, Guinness EA, Haldemann AFC, Herkenhoff K, Johnson J, Landis G, Li R, Lindemann R, McSween H, Ming DW, Myrick T, Richter L, Seelos FP, Squyres SW, Sullivan RJ, Wang A, Wilson J. Localization and physical properties experiments conducted by Spirit at Gusev Crater. Science 2004; 305:821-4. [PMID: 15297662 DOI: 10.1126/science.1099922] [Citation(s) in RCA: 144] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The precise location and relative elevation of Spirit during its traverses from the Columbia Memorial station to Bonneville crater were determined with bundle-adjusted retrievals from rover wheel turns, suspension and tilt angles, and overlapping images. Physical properties experiments show a decrease of 0.2% per Mars solar day in solar cell output resulting from deposition of airborne dust, cohesive soil-like deposits in plains and hollows, bright and dark rock coatings, and relatively weak volcanic rocks of basaltic composition. Volcanic, impact, aeolian, and water-related processes produced the encountered landforms and materials.
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Bell JF, Squyres SW, Arvidson RE, Arneson HM, Bass D, Blaney D, Cabrol N, Calvin W, Farmer J, Farrand WH, Goetz W, Golombek M, Grant JA, Greeley R, Guinness E, Hayes AG, Hubbard MYH, Herkenhoff KE, Johnson MJ, Johnson JR, Joseph J, Kinch KM, Lemmon MT, Li R, Madsen MB, Maki JN, Malin M, McCartney E, McLennan S, McSween HY, Ming DW, Moersch JE, Morris RV, Dobrea EZN, Parker TJ, Proton J, Rice JW, Seelos F, Soderblom J, Soderblom LA, Sohl-Dickstein JN, Sullivan RJ, Wolff MJ, Wang A. Pancam multispectral imaging results from the Spirit Rover at Gusev Crater. Science 2004; 305:800-6. [PMID: 15297658 DOI: 10.1126/science.1100175] [Citation(s) in RCA: 130] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Panoramic Camera images at Gusev crater reveal a rock-strewn surface interspersed with high- to moderate-albedo fine-grained deposits occurring in part as drifts or in small circular swales or hollows. Optically thick coatings of fine-grained ferric iron-rich dust dominate most bright soil and rock surfaces. Spectra of some darker rock surfaces and rock regions exposed by brushing or grinding show near-infrared spectral signatures consistent with the presence of mafic silicates such as pyroxene or olivine. Atmospheric observations show a steady decline in dust opacity during the mission, and astronomical observations captured solar transits by the martian moons, Phobos and Deimos, as well as a view of Earth from the martian surface.
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Christensen PR, Ruff SW, Fergason RL, Knudson AT, Anwar S, Arvidson RE, Bandfield JL, Blaney DL, Budney C, Calvin WM, Glotch TD, Golombek MP, Gorelick N, Graff TG, Hamilton VE, Hayes A, Johnson JR, McSween HY, Mehall GL, Mehall LK, Moersch JE, Morris RV, Rogers AD, Smith MD, Squyres SW, Wolff MJ, Wyatt MB. Initial results from the Mini-TES experiment in Gusev Crater from the Spirit Rover. Science 2004; 305:837-42. [PMID: 15297667 DOI: 10.1126/science.1100564] [Citation(s) in RCA: 141] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The Miniature Thermal Emission Spectrometer (Mini-TES) on Spirit has studied the mineralogy and thermophysical properties at Gusev crater. Undisturbed soil spectra show evidence for minor carbonates and bound water. Rocks are olivinerich basalts with varying degrees of dust and other coatings. Dark-toned soils observed on disturbed surfaces may be derived from rocks and have derived mineralogy (+/-5 to 10%) of 45% pyroxene (20% Ca-rich pyroxene and 25% pigeonite), 40% sodic to intermediate plagioclase, and 15% olivine (forsterite 45% +/-5 to 10). Two spectrally distinct coatings are observed on rocks, a possible indicator of the interaction of water, rock, and airfall dust. Diurnal temperature data indicate particle sizes from 40 to 80 microm in hollows to approximately 0.5 to 3 mm in soils.
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Greeley R, Squyres SW, Arvidson RE, Bartlett P, Bell JF, Blaney D, Cabrol NA, Farmer J, Farrand B, Golombek MP, Gorevan SP, Grant JA, Haldemann AFC, Herkenhoff KE, Johnson J, Landis G, Madsen MB, McLennan SM, Moersch J, Rice JW, Richter L, Ruff S, Sullivan RJ, Thompson SD, Wang A, Weitz CM, Whelley P. Wind-related processes detected by the Spirit Rover at Gusev Crater, Mars. Science 2004; 305:810-3. [PMID: 15297660 DOI: 10.1126/science.1100108] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Wind-abraded rocks, ripples, drifts, and other deposits of windblown sediments are seen at the Columbia Memorial Station where the Spirit rover landed. Orientations of these features suggest formative winds from the north-northwest, consistent with predictions from atmospheric models of afternoon winds in Gusev Crater. Cuttings from the rover Rock Abrasion Tool are asymmetrically distributed toward the south-southeast, suggesting active winds from the north-northwest at the time (midday) of the abrasion operations. Characteristics of some rocks, such as a two-toned appearance, suggest that they were possibly buried and exhumed on the order of 5 to 60 centimeters by wind deflation, depending on location.
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McSween HY, Arvidson RE, Bell JF, Blaney D, Cabrol NA, Christensen PR, Clark BC, Crisp JA, Crumpler LS, Des Marais DJ, Farmer JD, Gellert R, Ghosh A, Gorevan S, Graff T, Grant J, Haskin LA, Herkenhoff KE, Johnson JR, Jolliff BL, Klingelhoefer G, Knudson AT, McLennan S, Milam KA, Moersch JE, Morris RV, Rieder R, Ruff SW, De Souza PA, Squyres SW, Wänke H, Wang A, Wyatt MB, Yen A, Zipfel J. Basaltic rocks analyzed by the Spirit Rover in Gusev Crater. SCIENCE (NEW YORK, N.Y.) 2004; 305:842-5. [PMID: 15297668 DOI: 10.1126/science.1099851] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The Spirit landing site in Gusev Crater on Mars contains dark, fine-grained, vesicular rocks interpreted as lavas. Pancam and Mini-Thermal Emission Spectrometer (Mini-TES) spectra suggest that all of these rocks are similar but have variable coatings and dust mantles. Magnified images of brushed and abraded rock surfaces show alteration rinds and veins. Rock interiors contain </=25% megacrysts. Chemical analyses of rocks by the Alpha Particle X-ray Spectrometer are consistent with picritic basalts, containing normative olivine, pyroxenes, plagioclase, and accessory FeTi oxides. Mössbauer, Pancam, and Mini-TES spectra confirm the presence of olivine, magnetite, and probably pyroxene. These basalts extend the known range of rock compositions composing the martian crust.
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69
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McSween HY, Arvidson RE, Bell JF, Blaney D, Cabrol NA, Christensen PR, Clark BC, Crisp JA, Crumpler LS, Des Marais DJ, Farmer JD, Gellert R, Ghosh A, Gorevan S, Graff T, Grant J, Haskin LA, Herkenhoff KE, Johnson JR, Jolliff BL, Klingelhoefer G, Knudson AT, McLennan S, Milam KA, Moersch JE, Morris RV, Rieder R, Ruff SW, de Souza PA, Squyres SW, WaÌnke H, Wang A, Wyatt MB, Yen A, Zipfel J. Basaltic Rocks Analyzed by the Spirit Rover in Gusev Crater. Science 2004. [DOI: 10.1126/science.3050842] [Citation(s) in RCA: 209] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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Herkenhoff KE, Squyres SW, Arvidson R, Bass DS, Bell JF, Bertelsen P, Cabrol NA, Gaddis L, Hayes AG, Hviid SF, Johnson JR, Kinch KM, Madsen MB, Maki JN, McLennan SM, McSween HY, Rice JW, Sims M, Smith PH, Soderblom LA, Spanovich N, Sullivan R, Wang A. Textures of the Soils and Rocks at Gusev Crater from Spirit's Microscopic Imager. Science 2004. [DOI: 10.1126/science.3050824] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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71
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Herkenhoff KE, Squyres SW, Arvidson R, Bass DS, Bell JF, Bertelsen P, Cabrol NA, Gaddis L, Hayes AG, Hviid SF, Johnson JR, Kinch KM, Madsen MB, Maki JN, McLennan SM, McSween HY, Rice JW, Sims M, Smith PH, Soderblom LA, Spanovich N, Sullivan R, Wang A. Textures of the soils and rocks at Gusev Crater from Spirit's Microscopic Imager. SCIENCE (NEW YORK, N.Y.) 2004; 305:824-6. [PMID: 15297663 DOI: 10.1126/science.1100015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The Microscopic Imager on the Spirit rover analyzed the textures of the soil and rocks at Gusev crater on Mars at a resolution of 100 micrometers. Weakly bound agglomerates of dust are present in the soil near the Columbia Memorial Station. Some of the brushed or abraded rock surfaces show igneous textures and evidence for alteration rinds, coatings, and veins consistent with secondary mineralization. The rock textures are consistent with a volcanic origin and subsequent alteration and/or weathering by impact events, wind, and possibly water.
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72
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Morris RV, Klingelhöfer G, Bernhardt B, Schröder C, Rodionov DS, De Souza PA, Yen A, Gellert R, Evlanov EN, Foh J, Kankeleit E, Gütlich P, Ming DW, Renz F, Wdowiak T, Squyres SW, Arvidson RE. Mineralogy at Gusev Crater from the Mossbauer Spectrometer on the Spirit Rover. Science 2004; 305:833-6. [PMID: 15297666 DOI: 10.1126/science.1100020] [Citation(s) in RCA: 241] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Mössbauer spectra measured on Mars by the Spirit rover during the primary mission are characterized by two ferrous iron doublets (olivine and probably pyroxene) and a ferric iron doublet (tentatively associated to nanophase ferric iron oxide). Two sextets resulting from nonstoichiometric magnetite are also present, except for a coating on the rock Mazatzal, where a hematite-like sextet is present. Greater proportions of ferric-bearing phases are associated with undisturbed soils and rock surfaces as compared to fresh rock surfaces exposed by grinding. The ubiquitous presence of olivine in soil suggests that physical rather than chemical weathering processes currently dominate at Gusev crater.
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73
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Bertelsen P, Goetz W, Madsen MB, Kinch KM, Hviid SF, Knudsen JM, Gunnlaugsson HP, Merrison J, Nørnberg P, Squyres SW, Bell JF, Herkenhoff KE, Gorevan S, Yen AS, Myrick T, Klingelhöfer G, Rieder R, Gellert R. Magnetic Properties Experiments on the Mars Exploration Rover Spirit at Gusev Crater. Science 2004; 305:827-9. [PMID: 15297664 DOI: 10.1126/science.1100112] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The magnetic properties experiments are designed to help identify the magnetic minerals in the dust and rocks on Mars-and to determine whether liquid water was involved in the formation and alteration of these magnetic minerals. Almost all of the dust particles suspended in the martian atmosphere must contain ferrimagnetic minerals (such as maghemite or magnetite) in an amount of approximately 2% by weight. The most magnetic fraction of the dust appears darker than the average dust. Magnetite was detected in the first two rocks ground by Spirit.
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74
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Gellert R, Rieder R, Anderson RC, Brückner J, Clark BC, Dreibus G, Economou T, Klingelhöfer G, Lugmair GW, Ming DW, Squyres SW, D'Uston C, Wänke H, Yen A, Zipfel J. Chemistry of Rocks and Soils in Gusev Crater from the Alpha Particle X-ray Spectrometer. Science 2004; 305:829-32. [PMID: 15297665 DOI: 10.1126/science.1099913] [Citation(s) in RCA: 254] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The alpha particle x-ray spectrometer on the Spirit rover determined major and minor elements of soils and rocks in Gusev crater in order to unravel the crustal evolution of planet Mars. The composition of soils is similar to those at previous landing sites, as a result of global mixing and distribution by dust storms. Rocks (fresh surfaces exposed by the rock abrasion tool) resemble volcanic rocks of primitive basaltic composition with low intrinsic potassium contents. High abundance of bromine (up to 170 parts per million) in rocks may indicate the alteration of surfaces formed during a past period of aqueous activity in Gusev crater.
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75
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Bell JF, Squyres SW, Arvidson RE, Arneson HM, Bass D, Blaney D, Cabrol N, Calvin W, Farmer J, Farrand WH, Goetz W, Golombek M, Grant JA, Greeley R, Guinness E, Hayes AG, Hubbard MYH, Herkenhoff KE, Johnson MJ, Johnson JR, Joseph J, Kinch KM, Lemmon MT, Li R, Madsen MB, Maki JN, Malin M, McCartney E, McLennan S, McSween HY, Ming DW, Moersch JE, Morris RV, Dobrea EZN, Parker TJ, Proton J, Rice JW, Seelos F, Soderblom J, Soderblom LA, Sohl-Dickstein JN, Sullivan RJ, Wolff MJ, Wang A. Pancam multispectral imaging results from the Spirit Rover at Gusev Crater. SCIENCE (NEW YORK, N.Y.) 2004. [PMID: 15297658 DOI: 10.1126/science.1100175,2004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Panoramic Camera images at Gusev crater reveal a rock-strewn surface interspersed with high- to moderate-albedo fine-grained deposits occurring in part as drifts or in small circular swales or hollows. Optically thick coatings of fine-grained ferric iron-rich dust dominate most bright soil and rock surfaces. Spectra of some darker rock surfaces and rock regions exposed by brushing or grinding show near-infrared spectral signatures consistent with the presence of mafic silicates such as pyroxene or olivine. Atmospheric observations show a steady decline in dust opacity during the mission, and astronomical observations captured solar transits by the martian moons, Phobos and Deimos, as well as a view of Earth from the martian surface.
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