The Viking 1 site, in Chryse Planitia.
(The Viking Project, M. Dale-Bannister WU StL, NASA, apod010721)
The Viking 2 landing site, in Utopia Planitia.
(The Viking Project, M. Dale-Bannister WU StL, NASA, apod960722)
Water ice frost at the Viking 2 site. During the Martian winter, temperatures are so low that the atmosphere freezes out, as dry ice (carbon dioxide) snow. At mid-latitudes, such as the Viking 2 site, the dry ice quickly sublimes (evaporates) back into the atmosphere; but a layer of water ice and dust about a thousandth of an inch thick, which freezes out of the atmosphere with the carbon dioxide, remains on the surface for several months. (JPL, NASA, Planetary Photojournal) |
The Pathfinder landing site, with Sojourner rover next to "Yogi", near the center.
Click on image for larger view. (IMP Team, JPL, NASA, apod000514)
A panoramic view of the Spirit landing site (January 4, 2004). Click on image for larger view.
(Mars Exploration Rover Mission, JPL, NASA, apod040105)
Panoramic view of Rub al Khali, by Opportunity rover, 2005. Click on image for larger view.
(Mars Exploration Rover Mission, JPL, NASA, apod050822)
 Bright soil uncovered by the Spirit rover while trundling across the Martian landscape contains a high proportion of iron sulfates and other salts, probably created by the evaporation of mineral-rich waters, at some time in the past. This is one of many lines of evidence confirming the one-time presence of water on Mars. Unfortunately, there is no way to determine from present evidence whether water was present for long periods of time, or only as a result of hot springs associated with volcanic activity; and in any event, water cannot have been present in any significant amounts at most places on Mars at any time in the last 4 billion years, or the numerous ancient craters on the southern half of the planet would have been completely worn away, or at least show extensive signs of weathering and erosion. Still, the presence of water in any form, at any time, encourages those hoping to find (probably microscopic) fossil lifeforms. (Mars Exploration Rover Mission, Cornell, JPL, NASA, apod060406) |
 Unusually pitted boulders litter this Martian hillside. The surface of the boulders is so similar to similar pits, or vesicles, in gas-rich volcanic rocks on the Earth, that there is little doubt that the boulders were ejected from a volcano, at some time in the past. The large boulder close to bottom center is a little less than a foot and a half high, and was about six yards from the Spirit Rover when this image was taken, on April 13, 2006. As is true of most of the Mars, wind-blown sand covers most of the surface, and fine dust colors the sky. (Mars Exploration Rover Mission, Cornell, JPL, NASA, apod060515) |
 On the other side of Mars, the Opportunity rover had this view looking away from Victoria Crater, shortly after arriving there, in October 2006. In this exaggerated color image, a sea of gently undulating sand lies beneath a sky filled with wispy clouds. Depending upon the temperature at the clouds' altitude, they can be composed of either water ice, or carbon dioxide (dry) ice. (Mars Exploration Rover Mission, Cornell, JPL, NASA, (Image processing: Michael Howard, Tayfun Öner and Damien Bouic for unmannedspaceflight.com), apod061017) |
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