NASA's Spirit Stages Martian Stand-Up Performance

Meanwhile, the rover is sending home sections of a 360-degree color panorama it has taken and stored onboard, plus other information about the terrain around its landing site, Columbia Memorial Station in Mars' Gusev Crater.

Mission managers at NASA's Jet Propulsion Laboratory, Pasadena, Calif., have decided that changing the tilt of the lander platform will not be necessary before the rover drives off, possibly allowing drive-off to occur late Tuesday night or early Wednesday, Pacific Standard Time.

JPL's Chris Voorhees, who led the engineering team that planned the unfolding sequences for Spirit and its sister rover, Opportunity, said "Spirit has spent most of the last seven months scrunched up inside of a tetrahedral-shaped lander, and that is not the shape a rover wants to be. Over the last several days, Spirit has performed a sort of reverse robotic origami."

"The rover now stands at its full height and all six wheels are in position for driving on the surface of Mars," said Jennifer Trosper, mission manager at JPL.

The rover is still attached to the lander. The next step planned for Saturday evening (Pacific Standard Time) is to command the rover to release connections between the middle wheels and the lander. Under best-case conditions, severing the final cable connection is planned for Sunday night, followed by clockwise turns totaling 120 degrees on Monday night into Tuesday, then drive-off toward the northwest on the following martian day.

Pictures from Spirit's panoramic camera continue to provide details about the martian ground and sky. The rover transmitted home about 180 megabits of science data in the past martian day, nearly 10 times the maximum daily capability of Mars Pathfinder in 1997.

JPL geologist Dr. Matt Golombek, co-chair of the steering committee that evaluated potential landing sites for Spirit and Opportunity, said the pictures are confirming some predictions about the Gusev site. Rocks cover less of the ground than at the three previous Mars landing sites -- about three percent of ground area around Spirit compared with about 20 percent of the ground around each of Mars Pathfinder, Viking 1 and Viking 2.

Presenting the latest high-resolution color mosaic from Spirit, Golombek said, "This is without question the smoothest, flattest place we've ever landed on Mars, with the possible exception of Viking 2."

Dr. Mark Lemmon a member of the rover science team from Texas A & M University, College Station, said the atmosphere at Spirit's site is dustier than at previous landing sites, except during dust storms observed by the Viking landers. The dust colors the sky and affects the appearance of objects on the ground.

Higher above the ground, atmospheric densities predicted for Spirit's descent closely matched the true conditions measured from the spacecraft's deceleration, said JPL's Dr. Joy Crisp. That is a good sign for Opportunity's descent two weeks from now, though risks remain high for any landing on Mars.

Spirit arrived at Mars Jan. 3 (EST and PST; Jan. 4 Universal Time) after a seven-month journey. Its task is to spend the next three months exploring for clues in rocks and soil about whether the past environment in Gusev Crater was ever watery and suitable to sustain life.

Spirit's twin Mars Exploration Rover, Opportunity, will reach its landing site on the opposite side of Mars on Jan. 25 (EST and Universal Time; 9:05 p.m., Jan. 24, PST) to begin a similar examination of a site on the opposite side of the planet from Gusev Crater. As of Sunday morning, Opportunity will have flown 428 million kilometers (266 million miles) since launch and will still have 28 million kilometers (17 million miles) to go before landing.

JPL, a division of the California Institute of Technology in Pasadena, manages the Mars Exploration Rover project for NASA's Office of Space Science, Washington, D.C. Images and additional information about the project are available from JPL at http://marsrovers.jpl.nasa.gov and from Cornell University, Ithaca, N.Y., at http://athena.cornell.edu.