ESA Science & Technology - Publication Archive
Article appears in 'Laboratory Astrophysics and Space Research' (Ehrenfreund P. et al. Eds.), volume 236 in the Book series 'Astrophysics and Space Science Library'.
Published: 01 December 1998
Thermal Emission Spectrometer (TES) observations of the recession phase of Mars' south polar cap are used to quantitatively map this recession in both thermal and visual appearance. Geographically uniform behavior interior to the cap is characterized by defining several small regions which exemplify the range of behavior. For most of the cap, while temperatures remain near the CO2 frost point, albedos slowly increase with the seasonal rise of the Sun, then drop rapidly as frost patches disappear over a period of ~20 days. A "Cryptic" region remains dark and mottled throughout its cold period. TES observations are compared with the first-order theoretical spectra of solid CO2 frost with mixtures of dust and H2O. The TES spectra indicate that the Cryptic region has much larger grained sold CO2 than the rest of the cap and that the solid CO2 here may be in the form of a slab. The Mountains of Mitchel remain cold and bright well after other areas at comparable latitude, apparently as a result of unusually small size of the CO2 frost grains; we found little evidence for a significant presence of H2O. Although CO2 grain size may be the major difference between these regions, incorporated dust is also required to match the observations; a self-cleaning process carries away the smaller dust grains. Comparisons with Viking observations indicate little difference in the seasonal cycle 12 Martian years later. The observed radiation balance indicates CO2 sublimation budgets of up to 1250 kg m-3. Regional atmospheric dust is common: localized dust clouds are seen near the edge of the cap prior to the onset of a regional dust storm and interior to the cap during the storm.
Published: 26 April 2000
ESA's exciting and fast-track Mars Express mission is the first of the new flexible (F) missions, which are based on a new implementation scenario to maintain overall mission cost below a very stringent cost cap. The key features of an F-mission are streamlined management, up-front definition of the payload, and the transfer of more responsibility to industry. The cost ceiling is 175 MEuro for future F-missions, but only 150 MEuro for Mars Express. The scientific objectives of the mission include the remote and in-situ study of the surface, subsurface, atmosphere and environment of the planet Mars. ESA's Science Programme Committee preliminarily approved Mars Express in November 1998, provided sufficient funding would be available, and gave its full approval on 19 May 1999
Published: 01 July 1999
Made available online in October 2015.
Table of contents:
- Summary and scope
- Mission overview
- Programme participation
- Science and project management
- Operations and scientific data
- Acronyms Appendices
Published: 31 October 1997
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