Assessment of Mars Science and Mission Priorities (2003) / Chapter Skim
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8. Lower Atmosphere and Meteorology
8. Lower Atmosphere and Meteorology
Pages 64-70
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From page 64... ...
Our knowledge of the composition of the Mars atmosphere is based on measurements of minor gases such as Ne, Kr, and Xe, and ratios of common isotopes in the ambient atmosphere (36Ar/38Ar, i2C/~3C, 60/70, i60/~8O, i4N/~5N, 2H/iH) by the Viking descent mass spectrometer,4 ground-based and airborne spectroscopy,5 and laboratory analysis of atmospheric gases captured in the vitreous components of martian meteorites.6 It is thought that a combination of impact erosion and long-term atmospheric loss from the top of the atmosphere by solar wind sputtering and other processes,7 ~ and possibly sequestration of CO2 and other gases in the crust of the planet, are responsible for the present low atmospheric pressure at the surface of Mars (yearly average ~6 mbar)
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From page 65... ...
Results were in agreement with a reanalysis of the Viking data.2i A better understanding of color differences resulting from the solar phase angle when using reflectance spectroscopic and multicolor imaging by remote sensing helps in applying corrections when making composition measurements.22 A more thorough understanding of the effect of dust loading on atmospheric temperature was achieved during the highly successful aerobraking of MGS and the science mapping measurements made by the spacecraft's TES. Temperature profiles for most latitudes and seasons were also obtained.23 These, together with newly measured seasonal and spatial tidal amplitudes,24 can, when fully analyzed, be synthesized into Mars global climate/ circulation models, which will greatly improve predictions of Mars's atmospheric circulation and other details of Mars meteorology.
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From page 66... ...
Plans for the 2003 Mars Exploration Rover missions unfortunately do not include an atmospheric package on the landing stage, analogous to the meteorology station on Mars Pathfinder, a more modest mission. The European Space Agency's Mars Express mission, planned for launch in 2003, will measure the global distribution of water vapor, ozone, nitrogen, and carbon monoxide with its Planetary Fourier Spectrometer.
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From page 67... ...
An example of the flexibility of Earthbased measurements is shown in Figure 8.1, where atmospheric water vapor abundances around the Mars Pathfinder landing site are shown in precipitable microns. The ground-based measurements measured ~20 precipitable microns in the atmosphere in the geographical region surrounding the Pathfinder site, somewhat higher than the range of measurements made by the Imager for Mars Pathfinder, 6+4 precipitable microns.
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From page 68... ...
All of these issues are of critical importance and were called out in the 1994 COMPLEX report An Integrated Strategy for the Planetary Sciences: 1995-2010 (Appendix B: 4~.28 ASSESSMENT OF PRIORITIES IN THE MARS EXPLORATION PROGRAM In the past, and in this study, COMPLEX has attached very high priority to better understanding the martian atmospheric composition, chemistry, circulation, and concentration of near-surface water vapor as the key components of climate systems and to comparative studies of atmospheric dynamics and evolution. Identification of all atmospheric components present to as low as 10 ppm is essential for the knowledge in its own right and as a baseline for a wide range of other surface-composition and life-detection experiments.
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From page 69... ...
Farmer. "The Seasonal and Global Behavior of Water Vanor in the Mars Atmosohere: ~ .' is, , Complete Global Results of the Viking Atmospheric Water Detector Experiment," Journal of Geophysical Research 87: 2999-3019, 1982.
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From page 70... ...
Smith, and P Christensen, "Thermal Tides and Stationary Waves on Mars as Revealed by Mars Global Surveyor Thermal Emission Spectrometer," Journal of Geophysical Research 105: 9521-9538, 2000.
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