Scientific Invasion to Mars Starts Soon

May 12, 2003 -- When two rovers are launched to Mars this June, one thing NASA engineers hope they'll never have to confront is silence.

It was a painful silence that set in at Mission Control last February as the Columbia made its fateful descent to Earth. Silence also reigned as NASA controllers — and much of the world — breathlessly awaited the touchdown of the Mars Polar Lander in December 1999.

Just a few months earlier, scientists who had been hoping for signals from the Mars Climate Orbiter instead met a sickening quiet. The orbiter was lost just as it started to circle the Red Planet.

But thanks to intensive preparation and the reliance on old, dependable models, NASA scientists say they have reason to be confident they'll be hearing the beeps and churns of communication from two land rovers once they touch down on Mars.

The first of the two rovers (neither of which has yet named) is scheduled to launch between June 9 and June 19, followed by the second probe 10 days later. The twin rovers should land on Mars about six months later, in early January 2004.

Still, many hasten to add that landing a craft on the Red Planet — more than 36 million miles from Earth — can never be a guaranteed success.

Mars Overview: Click for an interactive...

"Let's not kid ourselves, sending something across the solar system and landing it on another planet is not like getting on an airplane and flying to L.A.," said Peter Christensen, a geologist at Arizona State University who has worked on an experimental device that will travel on one of the rovers. "It's a very risky business. But these teams are very talented and I think it's fair to say everything that can be done to make them work has been done."

Mars: A 'Harsh Mistress'

Back in 1999, errors behind the failed Mars Climate Orbiter and Mars Polar Lander programs appeared to stem from a harried staff working under the "Faster, Better, Cheaper" mantra coined by NASA's previous administrator, Dan Goldin.

Investigators found a failure to convert navigation data from English units used by one group of technicians to metric ones used by a different team likely caused the failure of the Mars orbiter. And some pointed to inadequate testing as one reason engineers failed to prevent the Mars Polar Lander's engine from apparently shutting down too early during its descent, causing it to crash.

"Mars has been a harsh mistress at times," said James Garvin, the lead scientist for NASA's Mars exploration program who is based at the agency's headquarters in Washington, D.C. "But we've spent three years doing every single effort imaginable to man or woman to make this a reliable experiment."

Garvin says the Mars 2003 teams have "tested to the max." They've also added extra gear to ensure the rovers stay intact and steady in Mars' cold, blustery environment.

Landing With a Bounce

Besides being thorough, NASA has tried to ensure a new success by borrowing from an old one.

The launch and spacecraft of both new probes are roughly based on the Mars Pathfinder, a probe that bounced to the Martian surface on July 4, 1997, and relayed data back to Earth for 10 weeks — nine weeks longer longer than expected.

The two new rovers, which are about the size of a golf cart, will have more power and greater mobility than the Pathfinder's Sojourner rover. Both should be able to trek up to 44 yards across the surface every Martian day (24 Earth hours and 37 Earth minutes).

But the landing for each is based on the old Pathfinder model.

The spacecraft's so-called aeroshell will protect it from fiery temperatures as it enters Mars' atmosphere. It will then release a hefty parachute based on one used by the Pathfinder. But the parachutes of the new Mars spacecraft are 40 percent larger than Pathfinder's since the new spacecraft are carrying loads 10,000 pounds heavier than the previous mission.

Finally, in a signature Pathfinder landing, huge, tough airbags will inflate and cushion each spacecraft's bouncy touch down. After it rolls to a stop, the airbags will fall away from the crafts and the petals of the landers will open and deploy like a flower.

Safe Landing Choices

The landing sites of the new Mars probe have also been chosen with safety in mind.

Steve Squyres, an astronomer at Cornell University in Ithaca, N.Y., and one of the mission scientists, has called the Meridiani Planum, one of the landing sites, among the "safest places on the planet."

In Mars terms, "safe" means being relatively free of rocks and dust and not too windy. At Meridiani, one of the probes will be testing for hematite, or iron oxide — a mineral that is often the product of rocks sitting in warm water.

The other landing site, the Gusev crater, where scientists think a water-filled lake once pooled, is relatively flat but may host some dangerously strong winds. Still, Garvin says engineers have designed the new spacecraft with strong materials and designs so they should be able to handle the gusts.

One thing engineers can do little about is the accumulation of dust on the probes' solar panels. As in past Mars rover missions, time spent roaming and communicating from the planet is limited by the life of a rover's solar panels that keep it powered.

Scientists have calculated the two probes should last at least 90 days before layers of dust shroud their panels and they turn cold. But, just as the Pathfinder's Sojourner lasted an extra nine weeks, Christensen is hopeful the new landers may last at least two to three times longer than planned.

"If only you could go out there with a wet rag and wipe them down," he said. "That would really keep them working."

Three Chances to Reach Mars

As NASA's probes hopefully roll their way around their Mars destinations, a third device should also be wandering on the planet.

The European Space Agency plans to launch its own Mars lander on June 1. The spacecraft, named Mars Express for its streamlined development, should also land in January and is programmed to explore a large flat region that overlies the boundary between ancient highlands and the northern plains.

The Mars Express' lander, named Beagle, will touch down using the Pathfinder's bounced landing model. With three planned Mars missions launching in one month, experts say there's reason to hope at least some will survive the long, perilous journey.

"If you go and look at the overall history of missions to mars, exploration has proven to be enormously risky," said John Pike, director of GlobalSecurity.org, a nonprofit organization focused on security and space issues.

"But we can probably be more confident," he added. "I think some of these upcoming missions will probably succeed. I just don't know which ones."