NASA's new Mars rover aims high. It's bigger, more powerful and more sophisticated than any other robotic vehicle that has landed on another planet. It will try to answer a big question: Has life existed elsewhere in the solar system?
Its very ambition has gotten the rover in trouble. Thanks to a mix of technological setbacks and engineering misjudgments, the rover's epic scale is matched by epic problems. Its story offers a cautionary tale as NASA plans to devote large chunks of its science budget in coming years to grand "flagship" missions, including a spacecraft to return Mars rocks to Earth and another that would visit a moon of Jupiter or Saturn.
The new rover, known as the Mars Science Laboratory, is $235 million, or 24%, over budget. Work on it has run so late that engineers are racing to prepare the rover for its blastoff in 2009. After that, the next good launch window, when Mars and the Earth are closest, is in 2011.
"They aimed high, and they got burned," says Arizona State University's Phil Christensen, a Mars scientist who helped review NASA's Mars program.
To make up for Mars Lab's ballooning cost, $1.2 billion, NASA has had to raid the coffers of other science projects.
Last month, the Mars rover Spirit, which has roamed the Red Planet since 2004, was threatened with being turned off to help pay for Mars Lab. After word spread, NASA rescinded cuts to Spirit and twin rover Opportunity.
'Pushing the envelope'
Spirit and Opportunity were a triumph for NASA, but next to Mars Lab, they'll look crude. Their job was to look for water. Their successor has a tougher task: to search for the molecules that are precursors to life and for evidence of microbes at work.
That requires a big machine that relies on nuclear power rather than the current rovers' solar panels. Mars Lab will carry a full chemistry workshop and a robotic drill arm for gathering rock samples.
Mars Lab, conceived in 2000 and given formal approval in 2006, "is the most challenging planetary mission that's ever been flown," says Doug McCuistion, head of NASA's Mars program. "We're pushing the envelope in a number of areas, and it just kind of built up."
Among the problems:
• The heat shield. Such a big rover needs heavy protection to get it through the Martian atmosphere. It took engineers until mid-2007 to determine that the material they'd chosen wouldn't work.
• The 90-plus motors that drive the rover's moving parts, such as its wheels. Engineers spent years working on cutting-edge motors. They decided last year that it would take too much time and money to develop them.
• The scientific instruments. Ranging from cameras to chemical sensors, the instruments ran so over budget that last year NASA officials kicked one instrument off the rover and stopped work on another. Work on the two instruments was restarted after corporate, foreign and federal sponsors outside NASA came up with more money.
• The landing system. Because it's so big, Mars Lab will touch down on the planet using a new combination of braking rockets, parachutes and a long tether that will lower it to the ground. Engineers encountered glitches developing the system.
Needed: 'Several miracles'
No single item can be blamed for the bulk of the cost growth, McCuistion says. It all added up.
"You ended up with several miracles (needed) to get the mission achieved, instead of just one," says Brown University planetary scientist John Mustard, chair of a group that provides Mars advice to NASA.
In retrospect, "we underestimated what it was going to take," concedes the lab's project manager, Richard Cook of NASA's Jet Propulsion Laboratory. "To do it right, we're going to need more funding."
What's more, every change has a ripple effect, Cook says. So the decision in 2007 to use different and heavier motors on the rover's moving parts meant that other weight-bearing parts of the rover had to be redesigned, upping the cost more.
Cook and others concede that they may have been able to head off some of the headaches by spending more money earlier than they thought was needed. That would have allowed them to experiment with new technologies without having so much of a ripple effect on the rest of the spacecraft.
Despite the missteps, Edward Weiler, the acting head of NASA's science division, says he'll do what it takes to fund the rover. Many NASA science projects will have take a small hit to pay for the overruns.
"I'm trying to spread the pain," Weiler says. "Everything is fair game."
Outside scientists agree with NASA officials that the rover is a difficult endeavor. They say it will be worth it, and anything less ambitious couldn't tackle the big questions Mars Lab will.
"Was it perhaps a quantum leap forward as opposed to an incremental step?" Mustard says. "Yes, that might be the case. But that's what NASA prides itself on."
MARS SCIENCE LABORATORY: BY THE NUMBERS
The Mars Science Laboratory, the next robotic vehicle to explore the surface of the Red Planet, will be far more sophisticated than the two Mars Exploration Rovers already roaming the planet.