The Mars rover has developed some minor problems that will probably delay the start of its trek across the rust-colored landscape to prospect rocks and soil, scientists said Wednesday.

NASA officials previously said the exploration could begin as soon as Monday but revised that timetable because of minor "hiccups" with an antenna and the air bags that cushioned the spacecraft's landing on Saturday.

It could be at least a week before the problems are fixed, said Art Thompson, tactical uplink lead on the mission.

"We are champing at the bit to get this puppy off of the lander and really get to drive this vehicle. That's why we're here," Thompson said.

Thompson said the air bag situation was not "a big issue" but the mission team wanted to be cautious. The Spirit remained in excellent health, NASA said.

An intermittent spike in one of two motors that drive an antenna on the rover has been resolved and is no longer a problem, scientists said.

On Tuesday, NASA scientists showed off the sharpest picture ever taken of the surface of Mars (search) — and quickly promised even bigger, better photos showing more of the reddish landscape strewn with rocks surrounding the Spirit rover (search).

Just days into its three-month mission, Spirit sent its first "postcard" home across 105 million miles of space to Earth.

Spirit used its robot equivalent of 20/20 vision to capture the photo, which has three to four times the resolution of previous Mars pictures.

"My reaction has been one of shock and awe," said Jim Bell of Cornell University, the main scientist on the rover camera team.

Spirit will spend the coming days preparing to roll off its lander and will continue snapping a full, 360-degree color panorama of its surroundings and transmit it to Earth.

"This is just the tip of the iceberg of what you're about to see," Steven Squyres of Cornell University, the mission's main scientist, said of the postcard released Tuesday.

President Bush telephoned to congratulate the mission team, calling Spirit's successful landing on Mars a "reconfirmation of the American spirit of exploration."

NASA Administrator Sean O'Keefe announced that Spirit's landing site would be named Columbia Memorial Station, in memory of the seven astronauts who died in February in the space shuttle disaster. The spacecraft also carries a plaque dedicated to the Columbia crew.

"Spirit carries the dream of exploration the brave astronauts of Columbia held in their hearts," O'Keefe said.

The National Aeronautics and Space Administration (search) said it has registered 1.25 billion hits on its rover-related Web sites, as computer users around the world log on to see more of the first pictures from the surface of Mars since the Pathfinder mission in 1997.

Spirit is half of an $820 million project. Its identical twin, Opportunity, should land on the opposite side of Mars on Jan. 24. The rovers, the size of golf carts, were designed to probe Mars for evidence it once might have been a warmer, wetter place conducive to life.

The postcard shows a vast plain scattered with a wide variety of rocks, including one in the far distance thought to be the size of a Volkswagen. Poking above the horizon, perhaps 16 miles to 19 miles away, a mesa could be seen standing against the reddish-pink of the Martian sky.

"After looking at these images, it leaves me a little bit speechless," said Jennifer Trosper, mission manager for surface operations.

NASA displayed the new image for reporters in high-definition television, a first for any pictures from another planet. A zoom-in showed off the crisp detail. Thousands of rocks peppered the scene, each blasted smooth by iron-rich dust lofted by the stiff winds thought to scour the area.

"We don't have the slightest idea of what these rocks are made of yet," Squyres said.

Scientists were especially intrigued by the thin crust on top of the Martian soil.

"It's strangely cohesive. We don't know what holds it together," Squyres said. He speculated that evaporating water could have left salts behind that cemented the Martian soil together.