Martian rover ready to roll

PASADENA - The United States robotic rover on Mars completed its transformation from folded landing craft to mobile explorer earlier than expected and may roll off its landing pad as soon as Wednesday, scientists at Nasa's Jet Propulsion Laboratory said yesterday.

The Spirit rover was set to begin a three-month search for signs of water on the Red Planet on Friday, but the ease of the stand-up manoeuvre and a quick fix to a problem with the lander has put the mission ahead of schedule.

On its seventh Martian day, or sol seven, Spirit flawlessly executed one of the most complex space deployments ever, morphing from its tetrahedron landing shape into a six-wheeled, golf cart-sized vehicle, scientists said.

The lander retracted a lift mechanism that raised Spirit to its full height, allowing the rover to push its front and rear wheels into place in the final steps of a "reverse robotic origami". said Chris Voorhees, mechanical systems engineer.

The Nasa team spent time on Saturday in the "test bed", a sort of Mars sandbox mocked up as the Spirit's landing site, trying to identify hazards in the rover's path.

The lander's front ramp is blocked by partially deployed airbags that scientists were unable to fully retract and test runs in the sand box showed the rover's right rear solar panel could snag on them, said mission manager Jennifer Trosper.

That led the Spirit team to settle on an alternative path down the back of the lander, which will require the rover to rotate from its south-facing position to face north-west.

If all goes as planned, the rover will move into place atop the lander tomorrow for a Wednesday exit.

The rover faces a 15cm drop from the edge of the lander's ramp to the planet's surface. It will probably drive about a half-metre on its first day - just enough to get all six wheels on to the planet.

In the intervening days, the team will cut the final cables holding Spirit to the lander and move a robotic arm laden with scientific instruments for the first time since it was lashed down for landing.

Scientists are thrilled with Spirit's ability to gather and transmit data of unprecedented detail and volume. Trosper said the craft had surpassed the capabilities of the 1997 Pathfinder rover by tenfold.

- REUTERS

Opportunity knocks

* Scientists are preparing for the January 24 landing of Spirit's twin rover, Opportunity.

* It is heading towards a site on the opposite side of the planet.

* Scientists completed an analysis of Martian weather during Spirit's landing to see if their forecast models needed to be tweaked for Opportunity's landing.

* Scientists selected landing sites in the huge Gusev crater for Spirit and on the Meridiani Planum for Opportunity.

* Data gathered by orbiting spacecraft suggested they once held water, and possibly some form of Martian life.

* Opportunity is expected to touch down in a rolling, dark-grey basalt plain.