Images give new insight into Mars' ancient rivers
NASA NEWS RELEASE
Posted: November 13, 2003
Newly seen details in a fan-shaped apron of debris on Mars may help settle a decades-long debate about whether the planet had long-lasting rivers instead of just brief, intense floods.
"Meanders are key, unequivocal evidence that some valleys on early Mars held persistent flows of water over considerable periods of time," said Dr. Michael Malin of Malin Space Science Systems, San Diego, which supplied and operates the spacecraft's Mars Orbiter Camera.
"The shape of the fan and the pattern of inverted channels in it suggest it may have been a real delta, a deposit made where a river enters a body of water," he said. "If so, it would be the strongest indicator yet Mars once had lakes."
Malin and Dr. Ken Edgett, also of Malin Space Science Systems, have published pictures and analysis of the landform in today's online edition of Science Express.
The fan covers an area about 13 kilometers (8 miles) long and 11 kilometers (7 miles) wide in an unnamed southern hemisphere crater downslope from a large network of channels that apparently drained into it billions of years ago.
No liquid water has been detected on Mars, although one of the previous major discoveries from Mars Global Surveyor pictures suggests some gullies have been cut in geologically recent times by the flow of ephemeral liquid water. Another NASA orbiter, Mars Odyssey, discovered extensive deposits of near-surface ice at high latitudes. Mars' atmosphere is so thin, over most of the planet, any liquid water at the surface would rapidly evaporate or freeze, so evidence of persistent surface water in the past is also evidence for a more clement past climate.
"Because the debris in this fan is now cemented, it shows that some sedimentary rocks on Mars were deposited by water," Edgett said. "This has been suspected, but never so clearly demonstrated before."
The camera on Mars Global Surveyor has returned more than 155,000 pictures since the spacecraft began orbiting Mars Sept. 12, 1997. Still, its high-resolution images cover only about three percent of the planet's surface.
JPL, a division of the California Institute of Technology, Pasadena, manages Mars Global Surveyor for NASA's Office of Space Science, Washington. JPL's industrial partner is Lockheed Martin Space Systems, Denver, which developed and operates the spacecraft. Malin Space Science Systems and the California Institute of Technology built the Mars Orbiter Camera. Malin Space Science Systems operates the camera from facilities in San Diego.