The great red planet road trip is finally under way.
At 3:40 a.m. EST yesterday NASA's Spirit rover rumbled down a cloth-covered ramp and dug its wheels into the Martian soil for the first time since touchdown two weeks ago.
The 10-foot journey took all of 78 seconds, but ended days of engineering angst over how to deal with an errant air bag that blocked the rover's primary exit.
With the song "Who Let the Dogs Out" booming in the background, elated mission controllers promptly uncorked pre-dawn champagne to celebrate. It is only the second time that a remote-control robot has driven the Martian dunes.
"We have six wheels in the dirt," said Charles Elachi, director of NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Mars is now our sandbox. We are ready to play and learn."
Like a tourist thrilled to finally step off the plane, the 380-pound robot's first act was to snap photos. One shot showed the Mars lander and a fresh trail of tread marks in the talcum-like soil.
Another picture revealed a pair of small rocks, dubbed "Sushi" and "Sashimi," a few yards ahead. The rocks could be one of the rover's first stops, said Albert Haldemann, the mission's deputy project scientist.
Parked three feet from the lander, Spirit will stay put for three Martian days while scientists calibrate its antenna and exercise its instrument-studded robotic arm.
The arm carries a microscope, two spectrometers and a diamond-tipped grinder that scientists will use to hunt for evidence that water once flowed at Gusev Crater, the spot near the Martian equator where Spirit touched down Jan. 3.
Cameras on Spirit and the lander have spotted several tantalizing scientific targets. There's a nearby depression dubbed Sleepy Hollow, and a large meteorite crater 825 feet away. The crater, an estimated 10 to 20 yards deep, may offer the first chance to study subsurface Martian geology up close, scientists said.
Beckoning on the horizon are a series of foothills rising above the Gusev plain. As much as two miles distant, the hills are five times farther away than Spirit was designed to rove during its 90-day mission.
Getting there will be up to a team of eight drivers who will steer the buggy from a windowless JPL control room more than 100 million miles away.
"Most people envision us as having a steering wheel and driving it like a radio-controlled car," said Brian Cooper, the lead driver. The reality, he says, is far cooler.
A radio signal takes almost 10 minutes to reach the rover, so real-time remote control is out. Instead, Cooper and his team rely on 3-D images beamed back by the rover's nine cameras.
By feeding the images into a computer, the engineers create a virtual road map of the Martian terrain. Then they don a pair of stereoscopic goggles to drive a simulated rover across the rock-strewn surface to help plot the best course to reach their next scientific goal.
"That way, we can be sure what we're asking the rover to do is safe," says Cooper. "It's the closet thing to being on Mars we can create."
Once a day, they'll issue a series of radio commands to the rover's navigation computer, which does the real-time driving.
Cooper, 44, is the Mario Andretti of Martian off-roading (although the race car icon never had a ride whose top speed was two inches per second).
In 1997, Cooper became the first person to drive on Mars, piloting NASA's pint-sized Sojourner rover. Afterward, he was jokingly issued a Mars driver's license. Signed by former Vice President Al Gore, it hung briefly in the Smithsonian Institution, he says.
But piloting Spirit will be a far more demanding task. The golf cart-size robot can trek up to 328 feet a day, about 30 times as far as its tiny predecessor. Sojourner understood 80 computer commands. To drive Spirit, Cooper and his team must be fluent in 900.
As it follows its plotted course, four black-and-white "hazcams" mounted on Spirit's chassis and two "navcams" fixed to its 5-foot-tall mast are designed to keep the rover from crashing into rocks and Martian potholes.
Yesterday's carefully rehearsed roll-off relieved several days of stress for the rover team. Spirit was originally supposed to drive off the lander during its ninth day on Mars. But an air bag that cushioned the rover's landing failed to deflate fully and blocked the main ramp, forcing Spirit to perform a slow, 115-degree turn to line up its wheels with a different ramp.
As Spirit prepares to leave its lander forever, scientists are eagerly awaiting the arrival of the rover's twin, Opportunity, which is to land Jan. 24 on the opposite side of the red planet.
If Opportunity arrives safely, it will mark the first time since NASA's Viking mission in 1976 that two spacecraft have operated simultaneously on Mars.