PASADENA, Calif. NASAs Spirit rover mission on Mars faces a little robotic cosmetic surgery today, a "lift and tuck" of a balky airbag that might impede the robot from rolling onto the surface of Gusev Crater.

"We want to get this puppy off the lander," said Thompson today during a morning press briefing. "Right now were a lander-centric mission."

"Our whole world is the lander we are sitting on," Thompson noted.

Engineers for Spirit are dealing with a nagging airbag issue.

One of the protective balloon-like bags that cushioned the lander as it bounded across the martian surface might snag the solar arrays of Spirit as its egresses onto Mars.

Spirit specialists plan an airbag adjustment today a lifting of a lander petal, then tucking in the slightly-inflated airbag under the platform.

"Were not stuckbut thats our first plan," Thompson said. "Were being cautious about this." If still a worry, engineers have other pathways to drive Spirit off its lander.

Another slice of Mars was unveiled today, taken by Spirits powerful Panoramic Camera (Pan Cam). Scientists are ecstatic about what they see. Gazing off into the distance, the Pan Cam has imaged a set of hills on the horizon, a little over a mile (2-kilometers) away.

Thats driving distance for Spirit, said Jim Bell, Payload Element Lead for the Pan Cam from Cornell University.

As each day of images reaches scientists, where to drive Spirit becomes more a heated debate. "Well keep our minds open," Bell said, about where to steer Spirit for the best science.

"Were ready to go," said Ray Arvidson, Deputy Principal Investigator from Washington University in St. Louis, Missouri. "We need our engineer buddies to get us off this lander and onto the surface."

Arvidson said that Gusev Crater remains an enigma.

The scene that scientists see at Gusev "is familiarbut a little bit alien," Arvidson said, compared to earlier Viking and Mars Pathfinder landing sites. He described it as a classic "desert pavement," but determining the layering of dust, rock, lakebed materials, and lava at the landing site is work still to do.

"Its a pretty complex site. Its not a simple lakebed," Arvidson said.

While the clock is ticking in getting Spirit off its stationary pedestal, another countdown is on the arrival of Opportunity.

It is screaming toward Mars, and headed for a landing site on the other side of the planet from Gusev Crater. Opportunity is now set for touchdown on January 24 at about 9:05 p.m. Pacific Standard Time.

"Mars has dealt us a complicated hand," said Joy Crisp, Project Scientist for the MER mission here at JPL. Airborne particles kicked up by a raging, but now diminishing dust storm on Mars, has dealt spacecraft engineers some issues.

Spirits entry, descent, and landing showed that the upper-atmosphere and high-altitude winds of Mars can be troublesome. Engineers are now debating such items as angle of entry, parachute deployment times, and other variables for Opportunitys plunge toward the red planet, Crisp told SPACE.com.

Opportunity is targeted to land at Meridiani Planum, a region containing exposed deposits of a mineral -- hematite -- that usually forms under watery conditions.

NASAs Mars Global Surveyor (MGS) is profiling the atmosphere over the Meridiani Planum landing zone. MGS is one of three orbiters -- two U.S. and the newly arrived European Space Agencys Mars Express -- now circling the red planet.

MGS atmospheric data is being pipelined into decision-making and debate this week about Opportunitys upcoming dive to Mars. Density and temperature structure of the atmosphere has been made all the more complex by the recent dust storm, Joy said.

"As this point, Im absolutely ecstatic about the performance of Spirit," said David Lavery, NASAs Program Executive for Solar System Exploration, charged with full-time responsibility for working the Mars Exploration Rover project.

"The anticipation of whats to come is the only thing gnawing at me a little bit. Im excited about getting six wheels dirty and thats what Im after," Lavery said.

Missions of the past, Lavery said, Viking, the Mars Pathfinder/Sojourner, and now the dual robots -- Spirit and Opportunity -- each has created a foundation for things to come.

"A 100 years from now, I think the most thrilling thing will be people standing on Mars who can go to these sites and look at them as truly historical sites of interestthe stepping stones for the exploration of Mars," Lavery told SPACE.com .