Mars Lake Held as Much Water as Lake Champlain Michael Reilly, Discovery News

 

Martian Lake Champlain | Discovery News Video

 

June 18, 2009 -- Nestled in a valley near the Martian equator, scientists have discovered the striking remnants of an ancient lake.

Though dry and frigid now, the traces it left behind hint at a water body younger than any other on the planet, and its sediments are a prime target for finding fossilized alien life.

When Mars coalesced billions of years ago it was much warmer, and probably wet. Features that appear to be eroded river deltas more than 3.7 billion years old dot parts of the planet's surface. Researchers have speculated they are evidence of lakes -- and primitive life may have once existed on the surface.

Now Gaetano di Achille and a team of researchers at the University of Colorado in Boulder have found an ancient shoreline ringing Shalbatana Vallis, a gash in Mars' surface just east of the massive volcanic province, Tharsis Rise.

They estimated from powerful images obtained using the powerful High Resolution Imaging Science Experiment (HiRISE) camera on board the Mars Reconnaissance Orbiter (MRO), that lake was 450 meters (1,476 feet) deep and nearly identical in volume to Lake Champlain in Vermont. Even more intriguingly, it dried up around 3.4 billion years ago -- 300 million years after the Red Planet's "warm and wet" phase is thought to have ended. And its deltas appear rich in fine-grained sediments, a sign that they've been relatively untouched by erosion.

"Deltas are high priority targets for exploration because they imply copious and long-lived water," team member Brian Hynek of the University of Colorado in Boulder wrote in an email to Discovery News. "And the sedimentation process is very effective at burying and preserving organic material."

The discovery could force a rethink of Martian climate history, but it's equally possible that it is an aberration. While the rest of the planet became cold and dry, volcanic heat from the Tharsis Rise could have released groundwater into the valley, and kept the lake ice-free for thousands of years.

"We need to be careful saying Mars was warm and wet," Patrick McGovern of the Lunar and Planetary Institute in Houston said. "Some experts think the features we see are a result of episodic pulses. Heat from an impact could have produced something like this lake, for instance."

Either way, the lake is a tempting place to look for fossilized alien life forms.

"Life wouldn't have arisen in this lake, but lakes on Earth provide many habitats for countless organisms," Hynek wrote. "This lake could have helped sustain and proliferate life on Mars, if it ever arose."