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Scientists directing NASA’s Mars Opportunity rover gushed with excitement as they announced that the aging robot has discovered a rock with a composition unlike anything previously explored on the Red Planet’s surface – since she landed on the exotic Martian plains 7.5 years ago – and which offers indications that liquid water might have percolated or flowed at this spot billions of years ago.
Barely three weeks ago Opportunity arrived at the rim of the gigantic 14 mile ( 22 km) wide crater named Endeavour after an epic multi-year trek, and for the team it’s literally been like a 2nd landing on Mars – and the equivalent of the birth of a whole new mission of exploration at an entirely ‘new’ landing site.
“This is like having a brand new landing site for our veteran rover,” said Dave Lavery, program executive for NASA’s Mars Exploration Rovers at NASA Headquarters in Washington. “It is a remarkable bonus that comes from being able to rove on Mars with well-built hardware that lasts.”
Opportunity has traversed an incredible distance of 20.8 miles (33.5 km) across the Meridiani Planum region of Mars since landing on January 24, 2004 for a 3 month mission – now 30 times longer than the original warranty.
“Tisdale 2” is the name of the first rock that Opportunity drove to and investigated after reaching Endeavour crater and climbing up the rim at a low ridge dubbed ‘Cape York’.
Endeavour’s rim is heavily eroded and discontinuous and divided into a series of segmented and beautiful mountainous ridges that offer a bonanza for science.
“This is not like anything we’ve ever seen before. So this is a new kind of rock.” said Steve Squyres, principal investigator for Opportunity at Cornell University in Ithaca, N.Y at a briefing for reporters on Sept. 1.
“It has a composition similar to some volcanic rocks, but there’s much more zinc and bromine than we’ve typically seen. We are getting confirmation that reaching Endeavour really has given us the equivalent of a second landing site for Opportunity.”
Tisdale 2 is a flat-topped rock about the size of a footstool that was blasted free by the impact that formed the tennis court sized “Odyssey” crater from which it was ejected.
“The other big take-away message, and this is to me the most interesting thing about Tisdale, is that this rock has a huge amount of zinc in it, way more zinc than we have ever seen in any Martian rock. And we are puzzling, we are thinking very hard over what that means,” Squyres speculated.
Squyres said that high levels of zinc and bromine on Earth are often associated with rocks in contact with flowing water and thus experiencing hydrothermal activity and that the impact is the source of the water.
“When you find rocks on Earth that are rich in zinc, they typically form in a place where you had some kind of hydrothermal activity going on, in other words, you have water that gets heated up and it flows through the rocks and it can dissolve out and it can get redeposited in various places,” Squyres explained.
“So this is a clue, not definitive proof yet, but this is a clue that we may be dealing with a hydrothermal system here, we may be dealing with a situation where water has percolated or flowed or somehow moved through these rocks, maybe as vapor, maybe as liquid, don’t know yet.”
“But it has enhanced the zinc concentration in this rock to levels far in excess of anything we’ve ever seen on Mars before. So that’s the beginning of what we expect is going to be a long and very interesting story about these rocks.”
Endeavour crater was chosen three years ago as the long term destination for Opportunity because it may hold clues to a time billions and billions of years ago when Mars was warmer and wetter and harbored an environment that was far more conducive to the formation of life beyond Earth.
Signatures of clay minerals, or phyllosilicates, were detected at several spots at Endeavour’s western rim by observations from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) aboard NASA’s Mars Reconnaissance Orbiter (MRO).
“The motherlode of clay minerals is on Cape Tribulation. The exposure extends all the way to the top, mainly on the inboard side,” said Ray Arvidson, the rover’s deputy principal investigator at Washington University in St. Louis.
Phyllosilicates are clay minerals that form in the presence of pH neutral water and which are far more hospitable to the possible genesis of life compared to the sulfate rich rocks studied in the more highly acidic aqueous environments examined by both the Opportunity and Spirit rovers thus far.
“We can get up the side of Cape Tribulation,” said Arvidson. It’s not unlike Husband Hill for Spirit. We need to finish up first at Cape York, get through the martian winter and then start working our way south along Solander Point.
The general plan is that Opportunity will probably spend the next several months exploring the Cape York region for before going elsewhere. “Just from Tisdale 2 we know that we have something really new and different here,” said Squyres.
“On the final traverses to Cape York, we saw ragged outcrops at Botany Bay unlike anything Opportunity has seen so far, and a bench around the edge of Cape York looks like sedimentary rock that’s been cut and filled with veins of material possibly delivered by water,” said Arvidson. “We made an explicit decision to examine ancient rocks of Cape York first.”
So far at least the terrain at Cape York looks safe for driving with good prospects for mobility.
“The good news is that, as predicted, we have hard packed soils like the plains at Gusev that Spirit saw before getting to the Columbia Hills,” said Arvidson. “The wheel tracks at Cape York are very, very shallow. So if anything we will have some skid going downhill the slopes of 5 to 10 degrees on the inboard side which we can correct for.”
“We are always on the lookout for sand traps. We are particularly sensitized to that after the Spirit situation. So far it’s clear sailing ahead.”
Opportunity will then likely head southwards towards an area dubbed “Botany Bay” and eventually drive some 1.5 km further to the next ridge named Cape Tribulation and hopefully scale the slopes in an uphill search for that mother lode of phyllosilicates.
“My strong hope – if the rover lasts that long – is that we will have a vehicle that is capable of climbing Cape Tribulation just as we climbed Husband Hill with Spirit. So it’s obvious to try if the rover is capable, otherwise we would try something simpler. But even if we lose a wheel we still have a vehicle capable of a lot of science,” Squyres emphasized. “Then we would stick to lower ground and more gently sloping stuff.”
“The clear intention as we finish up at Cape York, and look at what to do next, is that we are going to work our way south. We will focus along the crater’s rim. We will work south along the rim of Endeavour unless some discovery unexpectedly causes us to do something else.”
“We will go where the science takes us !” Squyres stated.
Opportunity is in generally good health but the rover is showing signs of aging.
“All in all, we have a very senior rover that’s showing her age, she has some arthritis and some other issues but generally, she’s in good health, she’s sleeping well at night, her cholesterol levels are excellent and so we look forward to productive scientific exploration for the period ahead,” said John Callas, project manager for Opportunity at NASA’s Jet Propulsion Laboratory in Pasadena, Calif.
“This has the potential to be the most revealing destination ever explored by Opportunity,” said Lavery. “This region is substantially different than anything we’ve seen before. We’re looking at this next phase of Opportunity’s exploration as a whole new mission, entering an area that is significantly different in the geologic context than anything we’ve seen with the rovers.”
Read Ken’s continuing features about Mars starting here
Opportunity Arrives at Huge Martian Crater with Superb Science and Scenic Outlook
Opportunity Snaps Gorgeous Vistas nearing the Foothills of Giant Endeavour Crater
Dramatic New NASA Animation Depicts Next Mars Rover in Action
Opportunity Rover Heads for Spirit Point to Honor Dead Martian Sister; Science Team Tributes
Opportunity Rover Completes Exploration of fascinating Santa Maria Crater
Opportunity Surpasses 30 KM Driving and Snaps Skylab Crater in 3 D