Assessment of Mars Science and Mission Priorities (2003) / Chapter Skim
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4. Stratigraphy and Chronology
4. Stratigraphy and Chronology
Pages 26-33
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From page 26... ...
Geologic Units and the Stratigraphic Column The Mariner 9, Viking orbiter, and Mars Global Surveyor spacecraft have provided a wealth of data from which the types and abundances of Mars's geological units can be surveyed, their relative stratigraphic ages derived, and their absolute ages estimated. The planet's various geological units are distinguished and characterized on the basis of their morphologic, topographic, and spectral properties.
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From page 27... ...
A correspondence between absolute ages and crater densities has not been established with confidence. The figure is subject to amendment; it shows Tharsis volcanism to have occurred in the Hesperian epoch, but recent Mars Global Surveyor data have indicated that the Tharsis complex of volcanoes was formed in the upper Noachian epoch.
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From page 28... ...
Adapting the lunar production curve to Mars requires knowledge of the difference in impact rates between the planetary bodies; the nature of crater-forming projectiles; and the effects of differing gravity, impact velocity, and target properties on impact crater formation. i2 Modeling of these parameters permits an estimate of the ratio of the lunar to martian production functions, allowing estimation of martian crater ages to within about a factor of two i3,~4 The factor-of-two uncertainty in age has relatively little effect on interpretation of the absolute age of Noachian terrains, expected to have been originally nearly saturated with craters.
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From page 29... ...
Absolute Chronology NEAR-TERM OPPORTUNITIES Orbiter missions provide the opportunity for imaging and spectroscopic studies that can aid stratigraphic and geological analyses and enable improved crater statistics and understanding of geological processes, including erosion and exhumation. The 2001 Mars Odyssey mission carries the Thermal Emission Imaging System (THEMIS)
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From page 30... ...
NASA's 1996 Mars Expeditions Strategy Group report points out that in situ surface studies are essential,36 but in order to employ appropriately sophisticated and high-precision experiments, "the essential analyses of selected samples must be done in laboratories on Earth" [7.31. ASSESSMENT OF PRIORITIES IN THE MARS EXPLORATION PROGRAM The Mars Exploration Program outlined in Appendix A includes the broad goals of understanding the climate and the geological history of the planet within the overarching theme "Follow the water." These goals encompass
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From page 31... ...
High-resolution imaging also plays a practical role in Mars exploration, being essential to considerations of safety, choice of landing sites, establishment of the context for in situ analyses and returned samples, navigational support for rovers, and so on. The Mars Reconnaissance Orbiter imager and the Mars Express HRSC are expected to accomplish these goals for geological units of interest, and also to provide context imaging and spectroscopy.
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From page 32... ...
Ryder, "Stratigraphy and Isotope Ages of Lunar Geologic Units: Chronological Standard for the Inner Solar System," Space Science Reviews 96: 9-54, 2001.
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From page 33... ...
, "Mars Exploration Program: Scientific Goals, Objectives, Investigations, and Priorities, in Science Planning for Exploring Mars," JPL Publication 01-7, Jet Propulsion Laboratory, Pasadena, Calif., 2001.
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