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Volumn 287, Issue 5458, 2000, Pages 1626-1630

A global view of martian surface compositions from MGS-TES

Author keywords

[No Author keywords available]

Indexed keywords

MINERAL;

EID: 0034094308     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.287.5458.1626     Document Type: Article
Times cited : (576)

References (44)
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    • -1 sampling [P. R. Christensen et al., J. Geophys. Res. 97, 7719 (1992)]. The instrument also contains bore-sighted thermal (5 to 100 μm) and visible/near-infrared (VNIR) (0.3 to 3.5 μm) bolometers. The focal planes for the interferometer and the bolometers consist of three cross-track and two along-track detectors with an instantaneous field of view (IFOV) of ∼8.5 mrad. The TES instrument uses a pointing mirror that allows for limited targeting capability, limb observations, image motion compensation (IMC), and periodic calibration by observing space and an internal reference surface. The final 2-hour circular mapping orbit of MGS provides a continuous data strip three pixels wide with a spatial sampling of ∼3 km by 9 km from a mean altitude of 379 km. The elongated pixel dimension is due to the final mapping orbit of MGS, which crosses the equator at ∼2 a.m. local time rather than the intended ∼2 p.m. because of damage to the spacecraft solar panel that required lower aerobraking rates. Spacecraft direction relative to the surface is reversed, and IMC does not produce adequate results when stepping the mirror in a direction opposite that originally intended. As a result, spatial sampling is smeared in the along-track direction. These data have improved regional coverage, spatial resolution, and radiometric precision over the aerobraking and science phasing data because of the characteristics of the final MGS 2 p.m. mapping orbit.
    • (1992) J. Geophys. Res. , vol.97 , pp. 7719
    • Christensen, P.R.1
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    • note
    • -1 for an average of all six detectors. Random error is lower in the averaged spectra presented here, reducing these uncertainties somewhat. Error due to the atmospheric correction was estimated and is similar to the errors shown in Fig. 1.
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    • _, J. Geophys. Res. 103, 1733 (1998).
    • (1998) J. Geophys. Res. , vol.103 , pp. 1733
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    • M. B. Wyatt et al., in preparation
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    • 2.
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    • in press
    • Most of the minerals used are from P. R. Christensen et al., J. Geophys. Res., in press. For a complete list, see the supplemental data available at Science Online at www.sciencemag.org/feature/data/1047493.shl.
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    • 2) content (25).
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    • Christensen et al. (3) performed a similar analysis on a surface spectrum from Terra Cimmeria to test the confidence of minor mineral percentages (<15%).
  • 28
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    • note
    • The spectra used were limited to surfaces warmer than 245 K, dust extinctions of <0.25, ice extinctions of <0.15, and RMS fits of measured to modeled spectra of <0.03. Because of the computationally extensive nature of temperature profile retrieval, dust and water-ice opacities were unavailable at the time of analysis. However, although opacity does not correlate perfectly with extinction, low extinctions will limit opacity for surfaces warmer than the atmosphere. Limiting the RMS error of the least-squares fit provides a quick method for filtering highly anomalous data due to errors such as lost bits, mislabeled calibration pairs, and compression errors. These criteria are less restrictive than those used to retrieve the spectral types because the fitting routine is more constrained with fewer end-members. TES emissivity spectra of warm surfaces under a variety of atmospheric and topographic conditions may be modeled with only dust, water-ice, and surface spectral shapes (1). While this only provides extinctions, rather than opacities, of atmospheric components, concentrations of each of the surface spectral units may be retrieved (2).
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    • R. Rieder et al., Science 278, 1771 (1997).
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    • note
    • We thank H. Moncrief, N. Gorelick, S. Anwar, K. Bender, K. Feely, K. Homan, and G. Mehall for software and operations support and M. Kraft, M. Smith, J. Pearl, W. Stefanov, S. Ruff, M. Wyatt, H. McSween, R. Morris, and J. Holloway for valuable discussions of the results presented here. We also thank the dedicated spacecraft and operations teams at Jet Propulsion Laboratory and Lockheed Martin.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.