PASADENA, CALIF. -- NASA's Spirit rover completed a series of three turns atop its lander yesterday, putting it in position to roll onto the surface of Mars and begin explorations, mission members said. The rover was expected to move about three metres off the lander and onto the surface early today, the 12th day of its mission.

The six-wheeled robot, which had been mostly immobile since landing Jan. 3, rolled about 25 centimetres on its platform Tuesday.

Yesterday, it completed the last of three turns that rotated it 115 degrees. It also had finished photographing its surroundings.

"Really there is nothing left to do on the lander for Spirit, so tomorrow we are going to egress onto the surface of Mars," mission manager Jennifer Trosper said.

Once Spirit is on the ground, it will take a parting photo of the inert lander with its rear cameras.

"We really want to see that," said Kevin Burke, a mechanical engineer overseeing the roll-off process.

The rover will first explore a crater and may then try to reach distant hills, a course roughly plotted out after National Aeronautics and Space Administration pinpointed Spirit's location on Mars.

"We know where we are now and we also know where we're going," said Steven Squyres, the mission's main scientist.

Spirit is expected to follow a meandering path in its search for evidence of the past presence of water on the dusty surface of Mars.