The spirit rover rolled on to Mars early yesterday, placing its six wheels on solid Martian ground for the first time since the robot bounced down on the Red Planet nearly two weeks ago. Engineers and scientists at Nasa's Jet Propulsion Laboratory (JPL) cheered after confirmation that the manoeuvre was a success.
Charles Elachi, the JPL's director, said: "Mars now is our sandbox, and we are ready to play and learn." Black-and-white pictures beamed from Spirit showed its two rear wheels on the Martian soil, with its lander behind it. Two parallel tracks led away from the lander.
"This is a big relief. We are on Mars. Spirit has landed," said Rob Manning, manager of the entry, descent and landing portion of the mission. "Our wheels are finally dirty."
Jennifer Trosper, the mission manager for surface operations, opened a bottle of champagne in celebration at a news conference. "Now we are the mission that we all envisioned three and a half years ago," she said.
Mr Elachi made reference to President George Bush's call on Wednesday for moon missions and long-term robotic and human journeys to Mars. "We at Nasa, we move awfully fast," he joked. "In less than 15 hours, we are doing our first step."
Spirit was to have taken less than two minutes to travel the three metres from the unfolded petals of its lander on to Mars. Engineers said the move was likely to be the riskiest of Spirit's three-month mission. Engineers delayed the move for three days to give Spirit time to reposition itself on top of its lander, where it had sat since arriving. Spirit had to turn 115 degrees to line up with one of the exit ramps that ring the lander.
Originally, Spirit was to roll straight off the lander on its ninth day on Mars. But the now-deflated air bags that cushioned the rover's landing blocked that way, forcing Spirit to perform a slow pirouette, turning clockwise in three separate moves.
Mission plans called for Spirit to spend several days parked beside its lander after rolling off, giving it time to find its bearings and perform a preliminary analysis of the soil and rocks around it.
Nasa then planned for Spirit to begin a meandering trip in the direction of an impact crater about 825 feet away. Spirit was designed to travel dozens of yards a day. On its way, it will prospect for geological evidence that the now dry planet was once wetter and hospitable to life. Spirit landed in the middle of Gusev Crater, a 95-mile-wide depression scientists believe was once a lake.
Even while parked, the vehicle was busy. It used its nine cameras to take at least 3,900 pictures of its surroundings. Mission scientists used those images, including sweeping panoramas, to chart the rover's planned movements.
The $820m (£450m) project also includes a second, identical rover named Opportunity. Spirit's twin should land on the opposite side of the Red Planet on 24 January. Sojourner, the much smaller rover that Nasa landed on Mars in 1997, spent one day on top of the Pathfinder lander before moving off to roam.