PASADENA, July 6: Sojourner, Nasa's six-wheeled rover the size of a microwave oven, inched down a metal ramp and on to the frigid Martian soil last night, becoming the first mobile vehicle to roll on to another planet.The first pictures from the rover on Mars showed it wheeling away from the edge of the ramp.

``We just want to thank you for the lift. Now we're on our own,'' a rover team member announced at mission control.

As the rotation of Mars began to carry it out of radio contact with Earth, the pride of NASA's Pathfinder mission was expected to lower a sophisticated instrument to the ground and begin sniffing out its new surroundings.It was the last major planned activity on a day that began with anxiety.

The solar-powered rover had ceased communicating with the main lander on Friday night, even though it was still latched to one of the main craft's three solar panels. But when the time came for the rover and Pathfinder to awaken on Saturday, Sojourner was communicating just fine.

``We feel like we've been invited back to the party,'' rover operator Matt Wallace said.

Moments after the `party' began, the lander's camera team unfurled a complete 360-degree panorama of Pathfinder's surroundings, assembled from 120 tiny snapshots.

The image looked for all the world like the US Southwest, with jumbled boulders scattered about a barren, table-flat plain and hills on the distant horizon.Later, mission controllers unfurled ramps in front of and behind the rover and then decided that Sojourner would descend on the rear ramp. But, for the first few days, the scientists will not allow the rover to travel much, preferring to use the time to learn to handle the vehicle.

Sojourner was expected on the surface before the Martian sunset, leaving it ready for action on Pathfinder's third day on the red planet.

First, controllers were to unfurl the front and rear ramps it uses to get down from the lander. Controllers resolved concerns that the ramps were blocked by a deflated air bag that cushioned Pathfinder's landing.

An anxious wait for word from Mars ended with jubilation when Mars Pathfinder radioed home that it was back in contact with its solar-powered rover after hours of uncertainty over its future.

``We have rover data,'' deputy project manager Brian Muirhead yelled shortly after Pathfinder began sending data on its second day on Mars. The only technical problem that remained on Saturday evening concerned the lander's computer, which had spontaneously reset itself the night before. The glitch did not cause any damage, but mission operators wanted to figure out why the computer had hiccuped before going on with the mission.

``The spacecraft is fine. The lander is fine,'' said mission manager Richard Cook. ``But we're a little perplexed as to what happened.''

Between the ramp release and the rover's departure, the lander's camera was to pop up to full height, about 1.7 metres that would increase the height of the distant hills in the camera's panoramic photos.

``All these features that you see in the distance have the potential to double in height, because we're going to double in height,'' said Peter Smith, the head scientist on the camera team and a professor at the University of Arizona.

Copyright © 1997 Indian Express Newspapers (Bombay) Ltd.