NASA plans to send twin rovers to Mars in 2003
BY WILLIAM HARWOOD
Posted: August 10, 2000
Using the same airbag landing technology pioneered by the Pathfinder mission in 1997, the new rovers will be about the size of golf carts and weigh about 113 kilograms (250 pounds).
They will each feature a suite of sophisticated instruments, a robot arm, high-resolution cameras and state-of-the-art computers for near-autonomous operation. The solar-powered vehicles will be capable of traversing about 100 meters (330 feet) per day, the distance Pathfinder's Sojourner rover covered in its entire lifetime.
"We are returning to a great adventure on the surface of Mars," said Scott Hubbard, NASA's recently named Mars program manager. "Twenty-five years ago, Viking changed our picture completely of what that barren landscape looked like. About three years ago, Mars Pathfinder showed us (new) technology and gave us some hints about what we could do with that technology.
"Now we're putting it all together, going back and doing some tremendous science," Hubbard said. "And we're going to take the public with us. Our plan is to return that data so everybody can see it just as soon as possible."
The now-defunct Mars Pathfinder and the currently orbiting Mars Global Surveyor were the first two missions in a planned scientific assault on Mars in which NASA planned to launch two missions every two years culminating in a robotic sample return mission in 2005.
But the second pair of spacecraft - the Mars Climate Orbiter and the Mars Polar Lander - were lost last year when they arrived at Mars. The Climate Orbiter crashed into the planet due to an embarrassing navigation oversight while the Polar Lander simply disappeared during atmospheric entry, presumably due to problems with a landing sensor.
In the wake of the highly publicized failures, NASA carried out wide-ranging investigations that identified major management and technical shortcomings in the "faster, better, cheaper" approach to planetary exploration.
The Mars program was put on hold while NASA reassessed its Mars strategy. In the near term, the agency decided to press ahead with plans to launch another orbiter later this year. But a lander virtually identical to the lost Polar Lander was grounded.
After pondering what sort of mission to mount in 2003, NASA managers today announced plans to launch not one but two landers, a bold project that, if successful, will put the Mars exploration program firmly back on track.
"During those discussions, it also became very clear that since '03 was such an excellent opportunity - and the last one for about six years - to do surface science, should we consider the possibility of doing two landers?"
In the end, Weiler said, the team concluded that "if you have the opportunity to do surface science and if you could do it for half the cost, maybe it would be a good idea to do two landers and land at two very different places, perhaps one place considered a safe landing site and perhaps another place that would be more aggressive."
Both rovers will be launched atop Boeing Delta 2 rockets, the first taking off on May 22, 2003, and the second following on June 4. If those dates hold up, one craft will land on Mars on Jan. 2, 2004, and the second 18 days later on Jan. 20.
"The goal of both rovers will be to learn about ancient water and climate on Mars," principal investigtator Steven Squyres of Cornell University said in a statement. "You can think of each rover as a robotic field geologist, equipped to read the geologic record at its landing site and to learn what the conditions were like back when the rocks and soils there were formed."
The first mission will cost between $350 million and $400 million, including the cost of the Delta 2 rocket. Hubbard said the second vehicle will cost just $200 million or so, including the cost of the launcher, pushing the project's total cost to around $600 million.
"Is this a step away from faster, better, cheaper? Is this going back to the good old days so to speak?" Weiler asked. "Think about it: Two landers for $600 million in today's dollars. Viking had two landers, no rovers, and the cost of Viking in today's dollars was several billion. So we're still on the order of one third or one quarter of what missions were like in the 1970s."
Still, $600 million is not cheap by anyone's yardstick and Weiler said the space science division could not afford the second lander on its own. The money to pay for the second rover will come from other agency budgets. But Weiler said the additional cost will not force NASA to cancel any other missions.
The price tag for the as-yet-unnamed 2003 project is driven in large part by recommendations that emerged from the failure investigations that followed the losses last year of the Climate Orbiter and Polar Lander.
"We are making sure that the budget, that the workforce and all the resource constraints are consistent with their recommendations, that there's adequate testing, that we don't shortchange any prudent process and that we do everything we can to ensure mission success," Hubbard said. "That will be our number one criteria."
And unlike the Polar Lander, which was designed to make its entry and descent while out of contact with Earth, the new landers will transmit signals all the way down to make sure engineers can figure out what happened if something goes wrong.
As with the Mars Pathfinder, the new spacecraft will hit the martian atmosphere about 120 kilometers (75 miles) above the surface at a velocity of about 22,500 kilometers per hour (14,000 mph). After falling to an altitude of about 11 kilometers (seven miles), a parachute will deploy to slow the descent.
Protective airbags will inflate at about 300 meters (1,000 feet) and the spacecraft will bounce and roll about 0.8 kilometers (0.5 miles) from the initial impact point. After the bags deflate, the rover's protective housing will open like the petals of a flower, clearing the way for the rover to roll away and begin its exploration.
Each spacecraft will be equipped with a steerable high-gain antenna capable of beaming up to 30 megabytes of data directly to Earth each day. Another 40 megabytes can be relayed back to Earth by NASA's 2001 orbiter, a planned French-built orbiter and a proposed Japanese spacecraft.
The landers will carry five scientific instruments. A high-resolution panoramic camera mounted atop each rover will be capable of taking pictures three times sharper than those from the Mars Pathfinder. An associated infrared camera will be used to identify minerals near the rover that may have been formed by interactions with water.
Each rover will feature a robot arm that will be equipped with three instruments for such close-up observations: Two spectrometers and a microscopic camera. In addition, the arms will be equipped with a rock abrasion tool, or RAT, that will grind into selected rocks to reveal their interior structure and composition.
Sophisticated computer equipment tied into multiple steering cameras will enable the rovers to autonomously move from point A to point B without intervention from ground controllers. They will steer around rocks or other obstacles standing more than 25 centimeters (10 inches) high and simply drive over smaller obstructions.
The rovers are expected to operate for at least 90 days and possibly longer, depending on how fast sunlight-obscuring dust builds up on the solar arrays.
"This mission is very exciting to me," said Squyres. "This mission is going to be, I truly believe, humanity's first great voyage of exploration of this new millenium.
"But in contrast to voyages of exploration of centuries past, we have the technology today to bring everybody along. One of the things we're going to do is essentially webcast the whole thing live as it happens. ... It's going to be a shared adventure for everybody who wants to come along."
Watch the proposed 2003 Mars Rover traverse the surface of the Red Planet and take close up measurements on a rock.
PLAY (547k, 46sec QuickTime file)