Assessment of Mars Science and Mission Priorities (2003) / Chapter Skim
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9. Climate Change
9. Climate Change
Pages 71-76
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From page 71... ...
Interannual Climatic Variability Martian climate variability on interannual time scales is an interesting topic from many points of view. Because of the short radiative time constant of the martian atmosphere and its lack of ocean heat storage, one would not expect the martian climate to undergo significant variations on interannual time scales.
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From page 72... ...
On Earth, physical and chemical climate records have proved to be the most valuable tools for studying and understanding quasi-periodic climate variability. Ice cores obtained in Greenland and Antarctica and deep-sea cores of ocean sediments contain a wealth of nearly continuous information about the state of the global climate system over the past 200,000 years.~° The exploration of Mars is at a much earlier stage than that of Earth, but what has been observed thus far suggests very strongly that accessible records of past martian climate variations may exist in the form of layered deposits in the martian polar regionsii and at midlatitudes.~2 Polar layered deposits visible on exposed scarps were first identified in Mariner 9 images,~3 and subsequent observations by Viking and Mars Global Surveyor (MGS)
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From page 73... ...
This problem is compounded by the fact that solar evolution models predict that the solar constant was significantly lower billions of years ago.~9 Nonetheless, the extreme complexity of the climate system and the many interactions between its various components and external forcing factors, such as solar variability, orbital variability, volcanism, and meteoritic and cometary impacts, make it possible that the early climate of Mars was warm and wet. Recent efforts to understand the history of volatiles and climate on Mars have established a broad framework that is consistent with evidence from spacecraft data, laboratory investigations, and theoretical studies.20 Although the earliest atmosphere was probably lost by impact erosion and hydrodynamic escape during the Early Noachian epoch, a relatively robust atmosphere appears to have been reestablished during the Noachian by primitive volatiles released during the creation of Tharsis by volcanic and igneous processes.
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From page 74... ...
NEAR-TERM OPPORTUNITIES The failed Mars Polar Lander mission, which attempted to land in the south polar layered deposits in 1999, represented a unique opportunity to learn more about the nature and potential of the deposits as records of Mars' s past climatic history. The Mars Odyssey orbiter, successfully launched in April 2001 and now operating in orbit about Mars, includes the Gamma-Ray Spectrometer (GRS)
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From page 75... ...
In the Mars Exploration Payload Assessment Group (MEPAG) report, climate is explicitly called out as one of four organizing themes for Mars scientific exploration.2i Highpnonty climate-related investigations recommended in the MEPAG report include determining the processes controlling the present distributions of Mars volatiles and dust using global mapping and landed observations [11.3.3]
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From page 76... ...
, "Mars Exploration Program: Scientific Goals, Objectives, Investigations, and Priorities," December 2000, in Science Planning for Exploring Mars, JPL Publication 01-7, Jet Propulsion Laboratory, Pasadena, Calif., 2001.
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