Red Planet was once blue, new study suggests
Published Wednesday, June 13, 2007 8:53PM EDT
Mars, the rugged Red Planet, may have once been blue, according to new research that suggests massive ancient oceans once covered a third of its surface.
The new findings by a joint Canada-U.S. research team provide strong evidence that ragged, kilometre-high features on the planet's surface are actually the shorelines of the ancient seas.
The team's findings are set to be released in the journal Nature on June 14.
Experts have debated the issue since the 1970s, when the Viking spacecraft located the features which seemed much like coastal formations on Earth.
Jerry Mitrovica, a physics professor at the University of Toronto and one of the authors of the study, told CTV.ca the new findings allow the scientific community to move forward.
"This gets us all on the same page. This debate about whether these oceans existed, clearly it's an important debate and one of the main issues people were trying to resolve," Mitrovica said.
Much of the debate erupted in the 1990s, after NASA's Mars Global Surveyor sent back topographical data that showed the dips and peaks along the features ranged up to three kilometres from the deepest dip to highest peak.
"If you walk along Lake Ontario, if you were to empty Lake Ontario you'd expect a rim that's relatively flat," Mitrovica told CTV News. "The problem is that these shorelines -- or whatever they were -- on Mars were anything but flat. They went up and down . . ."
On Earth, by comparison, similar shorelines remain relatively flat in comparison to sea level, casting doubt on the theory that the features marked the borders of an ancient ocean.
But Mitrovica argues that those dramatic topographical differences can be explained by the theory that the planet's spin axis shifted sometime in the past 2 to 3 billion years, deforming the shorelines and causing the geographic ups and downs.
A major shift of mass, possibly triggered by a volcanic eruption, caused the pole to wander about 50 degrees towards its current location, dramatically warping the topography and the ancient shorelines, he told CTV.ca.
Dr. Taylor Perron, the lead author of the study and a professor at Harvard University, explained how the researchers came to their conclusions.
"What we currently see on Mars is comparable to what you might see if you were to drain Earth's oceans and what you have left over is very smooth-floored basins and shorelines around the rim. The problem is that if you were to walk along the shorelines on Earth, they would be flat because shorelines form at sea level," Perron told CTV Newsnet.
"But if you were to do the same thing on Mars, walking along the shorelines there, you would rise and fall in elevation by two and a half kilometres and what we have been able to show is that these shorelines on Mars probably were flat at one point in the past, but that they have since been deformed by a large-scale warping of Mars' surface."
Perron pointed to the location of Tharsis -- a Martian volcano that is the largest in the solar system -- as proof.
He says the volcano is so massive, it will always reorient itself to sit on the planet's equator, and that the chances of this happening randomly are less than one in 10,000.
The team has not concluded what caused the pole to shift or what happened to the water thought to have once covered much of the surface -- though the questions have prompted some tantalizing theories.
"The ocean may have been gradually converted into water vapour, moved to higher elevations, and flowed beneath the surface. There could be a large mass of water deep within Mars," Perron suggested in a news release.
The new study was funded by NASA, the Canadian Institute for Advanced Research and the Natural Sciences and Engineering Research Council of Canada.
It follows a NASA announcement on May 21 that soil analysis conducted by the rover Spirit showed a 90 per cent concentration of silica -- some of the strongest evidence to that point that water was once present on the planet.
"The processes that could have produced such a concentrated deposit of silica require the presence of water," the NASA release stated.
"You could hear people gasp in astonishment," Steve Squyres, principal investigator for the Mars rovers' science instruments, said in the release.
"This is a remarkable discovery. And the fact that we found something this new and different after nearly 1,200 days on Mars makes it even more remarkable. It makes you wonder what else is still out there," said Squyres, of Cornell University, Ithaca, N.Y.
The team has laid out plans for further study of the soil patch and surrounding deposits.