July 20, 2012
Opportunity On A Martian Marathon Mission
Lawrence LeBlond for redOrbit.com - Your Universe Online
NASA, busy planning for the landing of its Curiosity rover on the Red Planet in August 2012, is perhaps getting into the Olympic spirit after the Mars Exploration Rover team announced Wednesday that another of its rovers, Opportunity, is on par to complete a Martian marathon.
When Opportunity landed on Mars in 2004, it was only planned to travel a mere 2,000 feet (less than a half mile). Yet, 8 years after its arrival on the remote world, the rover´s odometer is reading a distance nearly 60 times what it was supposed to travel. But not only has Opportunity surpassed its mileage-capability, traveling a mean 22 miles, just 4.2 miles short of a full marathon, it has also outlasted its planned 3 month mission directive.
Perhaps a testament to the abilities of those involved in the design, development and construction of such equipment, Opportunity´s sister rover, Spirit, also surpassed its lifespan of three months, remaining operational for six years on the harsh Martian world.
And while 22 miles in eight years sounds like that of a snail´s accomplished feat (actually a snail can travel upwards of 66 miles in a single year), given the fact that commands that come from Earth must travel at least 35 million miles to their designated drivers, it is a rather remarkable feat. Especially since, in science, it pays to be careful. NASA mission officials only command the rover to drive about 75 meters a day on average, saying quality of science is what matters most, not quantity.
Opportunity´s prime mission has been to search for signs of ancient water. Today, our sister planet is a bone-dry deserted world with an extremely thin atmosphere, with conditions deadly to nearly every known form of life here on Earth. But billions of years ago it may have been a much different story. Researchers believe that Mars was once warmer, wetter, and had the right ingredients for life to exist in some form. Opportunity´s mission is to hunt down clues that could prove those theories.
Opportunity first encountered signs of a watery past in deposits near the landing site in Eagle Crater. It found rocks that seemed to have formed in an ancient shallow lake. Over the next several years, it scavenged larger and deeper craters, and found even more evidence of a wet period on the planet. However, the evidence also showed signs of increased acidity, which may have been too harsh for life to exist in those particular spots.
Opportunity then set its sights on the Endeavour Crater -- an enormous pit 14 miles across and more than several hundred feet deep. A search of the depths of Endeavour would reveal a look farther back in the planets´ history, to a time when water was possibly less acidic and more favorable for life to exist.
The marathon mission was wrought with danger. Raging dust storms reduced solar power to Opportunity, almost sending it into a “sleep of death;” and soft, sandy, wind-blown ripples trapped the rover´s wheels, and it sustained a possibly mission-ending injury on its multi-mile trek: a failure in its right front steering actuator made running forward tricky. Ever resourceful, the rover ran part of its race backwards.
“The course took Opportunity over sedimentary bedrock made of magnesium, iron, and calcium sulfate minerals -- further indications of water billions of years ago,” said Ray Arvidson, Mars Exploration Rover Mission deputy principal investigator.
When the rover finally reached Endeavour Crater in August 2011, the excitement picked up in intensity. “Endeavor is surrounded by fractured sedimentary rock, and the cracks are filled with gypsum. Gypsum forms when ground water comes up and fills cracks in the ground, depositing hydrated calcium sulfate. This is the best evidence we've ever found for liquid water on Mars,” Arvidson added.
And while Opportunity has achieved a record that nobody here on Earth expected it would achieve, it falls short of holding the actual record for extraterrestrial miles traveled by a rover. That honor is held by the Soviet Lunokhod 2 rover that operated on the moon for four months and traveled 23 miles before falling into eternal slumber.
But NASA℠s little marathoner may not be done just yet. “We have no plans to stop running,” said Arvidson. It is doing so well that it may pass the 26.2-mile marathon finish line and just keep going.
And even if Opportunity beats Lunokhod 2´s record and completes an actual marathon, it may have a hard time holding that record once Curiosity makes landfall in August. The nuclear-powered behemoth will likely give Opportunity a run for its money.