Evidence of ancient Martian lakes, shallow seas found
NASA/JPL NEWS RELEASE
Posted: December 5, 2000
In what ultimately may be their most significant discovery yet, Mars scientists say high-resolution pictures showing layers of sedimentary rock paint a portrait of an ancient Mars that long ago may have featured numerous lakes and shallow seas.
Such layered rock structures where there were once lakes are common on Earth. The pancake-like layers of sediment compressed and cemented to form a rock record of the planet's history.
The regions of sedimentary layers on Mars are spread out and scattered around the planet. They are most common within impact craters of Western Arabia Terra, the inter-crater plains of northern Terra Meridiani, the chasms of the Valles Marineris, and parts of the northeastern Hellas Basin rim. The scientists compare the rock layers on Mars to features seen in the American Southwest, such as the Grand Canyon and the Painted Desert of Arizona.
"On Earth, sedimentary rocks preserve the surface history of our planet, and within that history, the fossil record of life. It is reasonable to look for evidence of past life on Mars in these remarkably similar sedimentary layers," said Malin. "What is new in our work is that Mars has shown us that there are many more places in which to look, and that these materials may date back to the earliest times of Martian history."
Malin added, "I have not previously been a vocal advocate of the theory that Mars was wet and warm in its early history. But my earlier view of Mars was really shaken when I saw our first high-resolution pictures of Candor Chasma. The nearly identically thick layers would be almost impossible to create without water."
As an alternative to lakes, Malin and Edgett suggest that a denser atmosphere on early Mars could have allowed greater amounts of windborne dust to settle out on the surface in ways that would have created the sedimentary rock.
"We have only solved one little piece of a tremendous puzzle," Malin said. "There is no illustration on the box to show us what it is supposed to look like when it is completed and we are sure most of the pieces are missing."
"These latest findings from the Mars Global Surveyor tell us that more study both from orbit and at the surface is needed to decipher the tantalizing history of water on Mars," said Dr. Jim Garvin, Mars Exploration Program Scientist at NASA Headquarters. "Our scientific strategy of following the water by seeking, conducting in situ studies, and ultimately sampling will follow up on these latest discoveries about Mars, and adapt to the new understanding."
"The finding of layered sedimentary deposits is something that biologists have been hoping for," said Dr. Ken Nealson, director of the Center for Life Detection at NASA's Jet Propulsion Laboratory (JPL), Pasadena, CA. "Perhaps the favorite sites for biologists to search for fossils or evidence of past life on Earth are layered lake or oceanic sediments such as in these sites Malin and Edgett describe."
The Mars Global Surveyor mission is managed by JPL for NASA's Office of Space Science, Washington, DC. Malin Space Science Systems built and operates the camera system. Lockheed Martin Astronautics, Denver, CO, developed and operates the spacecraft.