ITHACA, N.Y. -- After studying more than 9,500 images taken during the acclaimed Mars Pathfinder mission, scientists report in the latest issue of the journal Science (Dec. 5) that surface photographs provide strong geological and geochemical evidence that fluid water was once present on the red planet.
"We now have geological evidence from the Martian surface supportingtheories based on previous pictures of Mars from orbit that water played animportant part in Martian geological history," said James F. Bell, Cornellsenior research associate in astronomy and a member of the Mars Pathfinderimaging team.
Bell, along with lead author P. H. Smith of the University of Arizona;Robert J. Sullivan Jr., Cornell research associate in planetary science;and 23 other scientists authored the paper, "Results from the MarsPathfinder Camera." The report is part of a complete Mars Pathfindermission report published in Science.
During the first 30 days of the Mars Pathfinder mission, the Imager forMars Pathfinder (IMP) returned 9,669 pictures of the surface. Thesepictures appear to confirm that a giant flood left stones, cobbles androcks throughout Ares Vallis, the Pathfinder landing site. In addition tofinding evidence of water, the scientists confirmed that the soils are richin iron, and that suspended iron-rich dust particles permeate the Martianatmosphere.
Bolstering their evidence for once-present water, the imaging team foundevidence for a mineral known as maghemite -- a very magnetic iron oxide.Bell explained that maghemite forms in water-rich environments on Earth andcould likely be formed the same way on Mars. Bell explained that reddishrocks like Barnacle Bill, Yogi and Whale rock show evidence of extensiveoxidation on their surfaces. He said the oxidation -- or the rusting of theiron -- is possible only if water existed on the surface at some time andplayed an important role in the geology and geochemistry of the planet.
But, where did all the water go?
"That's the golden question. No one knows," said Bell, explaining thatseveral theories about the disappearing water exist, such as evaporationinto space, or seepage into sub-surface ice deposits or liquid aquifers, orstorage at the Martian poles. Bell said that robotic missions to Marsearly in the next century, including a Cornell-led rover mission to belaunched in 2001, will attempt to determine the water's whereabouts, aswell as to determine whether the Martian environment may once have beenmore conducive to life.
Mars Pathfinder's camera also revealed that Mars' atmosphere is more dustyand dynamic than expected, Bell explained. Surprisingly, the scientistsfound wispy, blue clouds, possibly composed of carbon dioxide (dry ice),traveling through Mars' salmon-colored sky. White cirrus-like clouds, madeof icy water vapor, also circulate throughout the thin Martian atmosphere.
"We were surprised to see such variations in the clouds, particularly sinceMars has such a thin atmosphere," Bell said. "We figured the atmospherewould be the same everyday, but there is a lot of real weather occurringthere. It's a small atmosphere, but a vigorous one."
Looking at Martian rocks like Yogi, Barnacle Bill and Scooby Doo revealsthat the rocks have been sitting on the planet's surface for billions ofyears, enduring a slow-motion sandblasting from a usually weak, dustyMartian wind. To carve rock with such a weak wind force requires a vastamount of time, Bell explained.
"The slow, persistent weathering and erosion of the rocks is like watertorture to the max," he said. "Mars really is an ancient world. We'restill trying to sort it all out."
Materials provided by Cornell University. Note: Content may be edited for style and length.
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