Science Source Feb 2010
EN_90286391_0398
Seasonal changes in south polar dune field on Mars. In this HiRISE image the distribution of dark streaks are not chaotic and their shapes are not fan-like; rather they are composed of confined, dozen-hundred meter long branches which follow the local topography and have accumulation zones at their end. We are learning a great deal from the enigmatic dark spots that are found throughout the south polar region. These dark spots may have resulted from cold gas jets that form by sublimation of the ice bringing entrained dust to the surface. Small dark streaks may have formed by avalanches of sand or they may be patches of coarse-grained ice that are clear enough so that the dark material below the ice is visible. The color image also provides helpful clues to understand this process. Bright white frost can be seen covering the surface. This frost is a probably a combination of frozen water and carbon dioxide ice. These bright patches are particularly prevalent along dune slip faces and around dark spots.
2010-02-13
EAST NEWS
Science Source
NASA
bk0405
0,59MB
17cm x 12cm przy 300dpi
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