Nasa scientists have freed a robot from the space probe Mars Pathfinder, allowing it to begin its exploration of the Red Planet at last.

The rover, known as Sojourner, has been stuck on Pathfinder since its successful landing on Mars two days ago.

It is the first time a man-made craft has travelled over the surface of another planet.

Pathfinder quickly sent back the evidence: an image of the Martian surface showing the tracks made by Sojourner's six studded titanium wheels.


The problem began when a partially-deflated airbag blocked Sojourner's way out of Pathfinder. Then the computers on board the probe and the rover failed to talk to each other.

Finally, at 0646 BST (0546 GMT) there was a breakthrough.

Flight director Chris Salvo announced to the waiting team at the Jet Propulsion Laboratory in California: "Six wheels on the ground."

There was an ecstatic cheer from the 70-strong team. But they will now have to wait another day for the first high-resolution pictures because an hour after the vehicle moved off the ramp, the sun went down and the rover was left parked until the next Martian morning.

Uneven terrain

The Sojourner is a tiny robot, about the size of a bread-bin and weighing just 22 lbs (10 kg). It travels on six wheels, each of which can move independently to cope with the uneven Martian terrain.

Most of the power is provided by solar cells on the roof, and there is also a battery power pack for backup.

It is controlled remotely from California, millions of miles away.

The Pathfinder probe had a near-perfect landing on 4 July - America's Independence Day - in the Ares Vallis, an ancient channel on Mars that may once have held water.

The first reading sent back was of the temperature - a freezing minus 93 degrees C.

The probe has also sent back some astounding pictures of the barren, rock-strewn surface.

It showed massive dust storms in the pink Martian sky, one raging just 600 miles (950 km) south of the landing site.

The mission is being followed avidly by millions on the internet through the official Mars Pathfinder website.

There is particular interest in what it may find following the controversial announcement by Nasa last August that it had found evidence of life in a Martian meteorite.

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