Rover let off its Martian leash

Nasa commanded its Spirit rover to move off its lander today and on to the surface of Mars for the first time since the six-wheeled robot bounced down on the Red Planet nearly two weeks ago.

Mission controllers at Nasa’s Jet Propulsion Laboratory radioed the command to the unmanned robot shortly after 8am Irish time.

The US space agency said it expected to hear whether the risky manoeuvre was a success about one to two hours later.

Nasa said Spirit would take less than two minutes to travel the 10 feet from the unfolded petals of its lander onto Mars. Engineers said the move would probably be the riskiest of Spirit’s entire three-month mission.

Engineers delayed the move for three days to give Spirit time to reposition itself on its lander, where it had sat since arriving. Spirit had to turn in place 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 some preliminary analysis of the soil and rocks around it.

Nasa then planned for Spirit to begin a meandering trip to its north-east, in the direction of an impact crater about 825 feet away. Spirit was designed to travel dozens of yards a day.

On its way, scientists said Spirit would prospect for geologic evidence that the now dry Red Planet was once wetter and hospitable to life. Spirit landed in the middle of Gusev Crater, a 95-mile-wide depression scientists believe contained a lake during the ancient past.

Even while parked, Spirit remained 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 project also includes a second, identical rover named Opportunity. Spirit’s twin should land on the opposite side of the Red Planet on January 24.

Sojourner, the far smaller rover that Nasa landed on Mars in 1997, spent a single day on the Pathfinder lander before shoving off to roam its surroundings. Spirit is far more complex and had to spend 12 days unfolding and readying itself.

Black-and-white pictures beamed from Spirit showed its two rear wheels on the Martian soil, with its lander behind it. Tyre 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.”

One team member unveiled a T-shirt bearing the slogan My Other Car Is On Mars.