Pasadena, Calif. ? Elated scientists at the Jet Propulsion Laboratory began plotting their strategy for exploring Mars on Sunday after landing NASA’s Spirit rover safely on the planet’s surface.

In the hours since Saturday’s successful touchdown, the golf cart-sized robot geologist has performed almost flawlessly, sending back more than 60 black and white photos of the planet’s surface. Panoramic color images were expected to begin arriving on Earth by early this morning.

“The science team has been very busy,” said Steve Squyres, a Cornell University professor and the mission’s principal scientist. “It has focused on the two obvious things: Where we are and where we’re going to go.”

Spirit’s home for its three-month mission is the Gusev Crater, a 95-mile wide depression slightly south of the Martian equator. Using images from Spirit’s descent cameras and other data, scientists have determined the probe hit its target with stunning accuracy — landing well within a 48-mile long, cigar-shaped target area and less than six miles from dead center.

Initial photos of Spirit’s surroundings on the Martian surface show a barren, windswept landscape strewn with small rocks. Before launch, researchers theorized the area was an ancient lakebed. If so, the rocks could hold evidence that water once flowed there. The presence of water might mean past conditions on Mars were favorable for the formation of life.

“They (project scientists) said we wanted to land on a dry lakebed,” said Ed Weiler, NASA’s associate administrator for space science. “That looks like a dry lakebed.”

Researchers characterized the location as the “science sweet spot” of Spirit’s possible landing zone. Photos from NASA satellites orbiting Mars show that small windstorms or “dust devils” have crisscrossed the area, making the rover’s job easier.

“What we wanted was someplace where the wind, where Mother Nature, has cleaned off the rocks for us,” Squyres said. “We’ve landed right in a place that’s so thick with dust devil tracks that a lot of the dust has been blown away.”

Geology mission

NASA Administrator Sean O'Keefe, in red, and Dr. Charles Elachi, director of the Jet Propulsion Laboratory, left, embrace while looking at the first photos arriving from Mars after the landing of the rover Spirit. The rover arrived Saturday night on the Red Planet and immediately began transmitting photographs; color images are expected to arrive today.

After a week or so of performing engineering tasks and charging its solar batteries, Spirit is expected to roll off its landing platform and begin studying the surrounding Martian landscape.

Like a human geologist, the six-wheeled rover will travel to interesting rocks, then examine them with a microscope, grinding tool and other instruments attached to an extendable arm.

Initial landing site images taken by Spirit showed no surrounding rocks or obstructions that would limit the rover’s movements.

“It is a place that almost, when you look at it, looks tailor-made for our vehicle,” Squyres said. “Our vehicle was built to drive. Our vehicle was built to explore. We see enough rocks that we can do great science with them, but not enough to get in our way.”

Several broad, pit-like depressions photographed by Spirit’s cameras already have piqued scientists’ curiosity. The nearby features, which may be filled with fine-grained dust, appear to have steep lips with exposed rocks.

Scientists are anxious to take a closer look. But while the depressions look fascinating, researchers are wary they could pose a hazard.

“We don’t know that the depression, which is filled with very smooth-looking soil, is not a rover trap,” Squyres said. “We want to get a good close look at that, make sure it’s nicely compacted stuff that we wouldn’t sink too deeply into.”

This mosaic image taken by the navigation camera on the Spirit rover shows a panoramic view of the rover on the surface of Mars.

All systems go

All of Spirit’s systems appear to be operating near perfectly. Flight controllers were working Sunday on two minor issues; neither was expected to have any impact on the mission.

Recent dust storms have made the Martian atmosphere more opaque than expected. That has reduced power production from Spirit’s solar arrays to 83 percent of the predicted level.

And because Spirit landed facing south, the rover’s camera mast often stands between the probe’s main antenna and Earth, creating the possibility of interference with communications.

This mosaic image taken by the navigation camera on the Mars rover shows a clear overhead view of the rover on the surface of Mars after its successful landing, Saturday. The National Aeronautics and Space Administration began receiving the first of an estimated 60 to 80 images from Spirit's cameras late Saturday, three hours after the robot made an apparently flawless landing on Mars. All photos shown were released Sunday.

Project engineers were working on a plan to move the antenna 180 degrees to ensure a clearer link.

A day after touchdown, many NASA managers appeared stunned at how perfectly the mission had gone so far.

In the weeks before the landing, program officials repeatedly had attempted to lower expectations, insisting that Spirit might not be heard from for hours and that information could be slow in coming. Few expected the torrent of images and data that started pouring in minutes after landing.

Weiler, noting that two-thirds of humankind’s previous missions to Mars had been failures, recently had gone so far as to refer to the Red Planet as the Death Planet.

This image taken by the Mars Global Surveyor highlights the same cluster of craters captured by the Mars rover as it descended to Mars Saturday.

“I would have been happy going to my hotel if we had heard a tone saying that we had landed,” Weiler told reporters early Sunday morning. “Tonight, you guys and gals got a symphony, and it was the most beautiful symphony I ever have heard.

“I will stop calling Mars the Death Planet.”

This image was taken by the hazard avoidance camera on the Mars Exploration Rover Spirit and shows the rover's front wheels in stowed configuration.

This image was taken by the hazard avoidance camera on Spirit and shows the rover's rear lander petal and, in the background, the Martian horizon. Spirit took the picture right after successfully landing on the surface of Mars.