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Contact: Mary Hardin, 818/354-0344
FOR IMMEDIATE RELEASE
December 4, 2000
EVIDENCE OF MARTIAN LAND OF LAKES DISCOVERED
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.
"We see distinct, thick layers of rock within craters and
other depressions for which a number of lines of evidence
indicate that they may have formed in lakes or shallow seas. We
have never before had this type of irrefutable evidence that
sedimentary rocks are widespread on Mars," said Dr. Michael
Malin, principal investigator for the Mars Orbiter Camera on
NASA's Mars Global Surveyor spacecraft and head of Malin Space
Science Systems (MSSS), San Diego, Calif. "These images tell us
that early Mars was very dynamic and may have been a lot more
like Earth than many of us had been thinking."
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 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
"We caution that the Mars images tell us that the story is
actually quite complicated, and yet the implications are
tremendous. Mars has preserved for us, in its sedimentary rocks,
a record of events unlike any that occur on the planet today,"
said Dr. Ken Edgett, staff scientist at MSSS and co-author of the
Science paper. "This is changing the way we think about the early
history of Mars -- a time perhaps more than 3.5 billion years
"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
"Mars seems to continually amaze us with unexpected
discoveries," said Dr. Edward Weiler, Associate Administrator for
Space Science at NASA Headquarters. "This finding just might be
the key to solving some of the biggest mysteries on Mars, and it
also tells us that our new Mars exploration program needs the
flexibility to follow up in a carefully thought-out manner."
"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 JPL. "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 the Jet
Propulsion Laboratory (JPL), Pasadena, Calif., for NASA's Office
of Space Science, Washington, D.C. Malin Space Science Systems
built and operates the camera system on Mars Global Surveyor.
Lockheed Martin Astronautics, Denver, Colo., developed and
operates the spacecraft.
Images for this release are available at
Information on Mars Global Surveyor is available at