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Spotlight On Mars - Image |
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Two Kinds of Ice |
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June 09, 2008 |
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Mars has two kinds of ice in its polar caps, frozen water and frozen carbon dioxide (dry ice)! To humans, they look the same -- snowy and white -- but a NASA spacecraft "sees" the difference with a special detector.
On Earth, dry ice doesn't form naturally and the main ingredient in our atmosphere (nitrogen) doesn't freeze because it doesn't get cold enough. On Mars, part of the carbon dioxide atmosphere freezes onto the poles each winter. In these images, icy, white Martian cliffs look different to the detector, with dry-ice frost shown in fluorescent green and water ice blue. The green areas are, in effect, frozen pieces of atmosphere.
Scientists are excited about seeing both ices because it helps them track seasonal changes in the polar ice caps. It also helps them explore strange phenomena, like geysers of carbon dioxide gas that erupt when the ices warm in spring.
Compact Reconnaissance Imaging Spectrometer for Mars, Mars Reconnaissance Orbiter
Image Credit: NASA/JPL-Caltech/Johns Hopkins University Applied Physics Laboratory
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