A spacecraft recently arrived at Mars has provided new evidence that fluids, likely including water, once flowed widely through underlying bedrock in a canyon that is part of the great Martian rift valley.
The new color images from the HiRISE camera aboard NASA's Mars Reconnaissance Orbiter show an equatorial landscape of hills composed of dozens of alternating layers of dark- and light-toned rocks, and crossed by dark sand dunes.
Within those layered deposits, the exquisitely detailed images show, there are a series of linear fractures, called joints, that are surrounded by "halos" of light-toned bedrock. In a paper to be published 16 February in the journal Science, published by the American Association for the Advancement of Science (AAAS), researchers argue that the "halos" offer clear evidence of past fluid flow through the bedrock.
Minerals in the fluid acted like cement to strengthen and bleach the rock, they say. The cemented rock proved more resistant to wind erosion than other features on the canyon walls and floor. It now serves as an exposed record of hydrological activity and offers a promising site to search for evidence of habitable niches in the Martian past.
Chris H. Okubo, the principal author of the paper and a postdoctoral researcher at the University of Arizona's Lunar and Planetary Laboratory, said the new images strongly suggest that subsurface fluids -- probably water, liquid carbon dioxide or a combination of the two -- once flowed abundantly in the western Candor Chasma region of Mars.
Okubo will discuss the paper during a 15 February news briefing at the 2007 AAAS Annual Meeting in San Francisco. The briefing also will include speakers from a 16 February Annual Meeting symposium on "The New Mars: Habitability of a Neighbor World."
Candor Chasma is one of several canyons that make up the great Martian rift valley called Valles Marineris. The rift valley would extend across t
Contact: Earl Lane
American Association for the Advancement of Science