“This is the single most powerful piece of evidence for liquid water at Mars that has been discovered by the Opportunity rover,” Cornell University planetary scientist Steve Squyres, lead researcher for Nasa’s Spirit and Opportunity Mars rovers, told reporters.
The twin-rovers, called Opportunity and Spirit, landed on opposite sides of Mars nearly eight years ago to search for signs of past water activity on the Red Planet. And now, finally, the rovers have returned a convincing evidence that Mars was not always as cold and dry as it is today.
It was unveiled this week at the American Geophysical Union conference in San Francisco that one of the most convincing proves is a thin vein of gypsum laced inside and protruding from an ancient rock along the rim of a 96-mile (154 km) wide crater Endeavour.
“Here, both the chemistry, mineralogy, and the morphology just scream water,” said Squyres during the 2011 winter meeting of the American Geophysical Union. “This is more solid than anything else that we’ve seen in the whole mission.”
After a three-year trek after having landed, Opportunity reached the 14-mile-wide (22-kilometer) Endeavour Crater this past August. Some time passed, it found the mineral vein, which is about 20 inches (51 centimeters) long and about the width of a human thumb.
Gypsum, in other words, plaster of Paris is to form from water flowing through rock. “This is the single most bullet-proof observation that I can think of that we’ve made this entire mission,” Squyres said.
Although the rovers have previously found evidence of other water-deposited minerals, many questions still remained.
“They’ve been moved around by wind. They’ve been mixing with other materials. It’s a big, jumbled up, fascinating mess,” Squyres said.
He added that the newly found gypsum is threaded into a rock: “This stuff formed right here. There was a fracture in the rock. Water flowed through it. Gypsum was precipitated from the water. End of story.”
Scientists want to examine other fracture-filled rocks when Opportunity heads for new ground after the Martian winter.
A similar discovery may be in store for the team working with NASA’s Mars Science Laboratory, a new, more sophisticated rover currently enroute to Mars. The robotic probe, named Curiosity, is due to land inside a 96-mile wide impact basin called Gale Crater on Aug. 6.
The crater has a layered plenty of deposits three miles high. “It’s like a strip chart recorder of geologic history,” planetary scientist Ray Arvidson, with Washington University in St. Louis, told reporters.
The two rovers’ missions were to last for three months, but both far outlived their warranties. NASA said Spirit dead just this year, and Opportunity is still used.
“She’s in excellent health,” said Bruce Banerdt, rover project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California. “This is far from being a rickety old rover.”
When asked whether the long-lived rover managed to complete just a 90-day mission, Washington University’s Arvidson added: “Are we out of warranty on this vehicle? You betcha. But we’re not done yet.”