One (Martian) year and counting
NASA's Mars rovers celebrate a full Martian year in space
By Sarah Wang 01/12/2006
Standing up to a harsh winter and overcoming many obstacles, JPL's twin Mars rovers Spirit and Opportunity have survived their first Martian year: the equivalent of 687 days on Earth, or nearly two Earth years.
And, apparently, it's been time and money - $900 million to date - well spent.
John Callas, JPL's deputy rover project manager, said the one-year mark on Mars is a remarkable and significant accomplishment.
"Mars has gone completely around the sun and they're still
in excellent health," Callas said of the robotic space pioneers. "They've still got an exciting adventure ahead of them."
Originally, the rovers were to survive only 90 Earth days on the Red Planet after their launch from Florida's Cape Canaveral in January 2004. But both have exceeded their original missions, covering an unexpected expanse of the Martian surface.
In more than four miles of travel, Opportunity has shot some 58,000 images of the planet.
Spirit has trekked three miles and also sent back thousands of images.
The rovers' primary mission is to determine whether water - the main ingredient for life - once flowed on the planet.
Some of the very first pictures Opportunity sent to Pasadena began to answer those questions, showing what scientists determined was clearly the effects of water erosion on rock.
Patterned layers of rock and ripple-like curves in some formations have lead scientists to conclude water once flowed on the surface of the planet. Scientists also discovered strange bead-like objects that are rich in hematite, a mineral that often forms in water.
And more recently, the rovers discovered rock that contained sodium chloride, or table salt, known to form only when water is present.
But the road to discovery has not been without obstacles for JPL researchers. Temperatures on Mars are extreme and can vary by as much as 100 degrees Celsius during the course of a Martian day.
Also, the solar-powered rovers require enough energy in the winter to keep warm, which proves to be a difficult task considering that surviving such temperatures requires the use of more power while receiving less sunlight.
Currently, Opportunity explores craters where impact has exposed materials otherwise buried under the Martian surface and otherwise inaccessible for study.
Meanwhile, Spirit has crested the summit of an area dubbed Husband Hill, named for deceased Columbia Commander Rick Husband, and is descending another hill toward an unexplored region of the planet.
Scientists directed Spirit to climb the hill so they could examine rock types formed at different times during the planet's history, and found new evidence of water at each altitude.
"We're finding abundant evidence for alteration of rocks in a water environment," said Ray Arvidson, a deputy principal investigator for the mission and a professor at Washington University in St. Louis, in a recent statement.
"What we want to do is figure out which layers were on top of which other layers. Understanding the sequence of layers is equivalent to having a deep drill core from drilling beneath the plains," he said.
Since there is nothing consumable on the solar-powered rovers, Spirit and Opportunity will keep on trekking until either something significant breaks or wears out. Martian wind storms blowing dust off the rovers' solar panels has been part of the reason for their extended life.
"When [the rovers] will give up their life, we can't say. It could be at any moment," said Callas. "A component could fail catastrophically because of the extreme environment that these rovers are in, and we could just never talk to the rover again. It could just die and that would be it."
Though so far a smashing success, the $900 million mission price tag has exceeded projected costs of $688 million.
Should exploration of a strange planet take priority over fixing the problems of our own, devastated by war, famine and disease?
But in the scale of current national spending, spending on exploration of Mars is really just a drop in the galactic bucket, said Mars Exploration Rover Project Scientist Joy Crisp.
"The NASA budget is less than 1 percent of our whole national budget, and the Mars portion of that budget is less than 3 percent of the NASA budget," she said.
"So even though $900 million sounds like a large number, it's small when you look at the grand scheme of what the government spends its money on."
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