Celebrations at NASA's Pasadena Jet Propulsion Laboratory, or mission control, continued as technicians put the rover through some early checks and commands, deploying the rover's solar panels, as the sun rises to power the craft for its coming exploration.
Spirit has already relayed its first black and white images of Mars back to jubilant NASA scientists, 360-degree colour images of the environment around Spirit were expected late on Sunday.
The six-wheeled rover is currently parked on the Gusev crater, an immense rock-strewn plain about 15 degrees south of the Martian equator.
"The focus of the next nine sols or however long it takes is getting the vehicle ready to explore," said Stephen Squyres, a geologist in charge of Spirit's scientific instruments. A sol is a Martian day.
"What you're going to see over the coming days is a gradual buildup of what will be an absolutely stunning pan-cam panorama of the terrain around this vehicle."
Ideal for exploring
The images seen thus far suggest that the surface around the vehicle is ideal for exploring.
"We're seeing a lot of exposed rock, but a very good surface for driving. It couldn't be better for what this vehicle was designed for," Squyres said.
Scientists hope that some of those rocks contain sediments that will reveal information about past conditions in the crater, which could be a dry lakebed.
Image taken 3 January 2004
on the surface of Mars
"If we can find sediments and if we can read the story that they have to tell, they can give us a great deal of information about what is was like in this place long ago," Squyres said.
"Was it warm? Was it wet? Was it the kind of place that might have been suitable for life? Our robot detectives are itching to get to work and try to start answering that question," he said.
The picture-perfect landing is a shot in the arm for the US space programme, which is still reeling from the loss nearly one year ago of the space shuttle Columbia, which disintegrated upon re-entry in Earth's atmosphere on 1 February 2003.
Memories of that disaster have been momentarily erased by the Spirit Rover's images.
The landing procedure began at about 03:22 GMT on Sunday when the probe successfully rotated its thermal shield forward to protect it from the heat of the Martian atmosphere.
Initial pictures, showing open spaces between surrounding rocks, hold promise that Spirit will be able to drive across the Gusev crater relatively unhindered
NASA expects to spend around a week preparing the rover for its exploration of Mars. During the preparations, its cameras will scan the surrounding environment and determine its initial objectives.
Initial pictures, showing open spaces between surrounding rocks, hold promise that Spirit will be able to drive across the Gusev crater relatively unhindered.
Jump for joy
Scientists jumped of joy when they heard a signal relayed by the Mars Global Surveyor satellite, indicating that Spirit had survived its landing.
The space probe plunged through the fiery Martian atmosphere for six minutes, then bounced along the planet's rocky surface, with an approximate landing time of 04:35 GMT on Sunday.
There were hugs when a signal
indicated craft was still functioning
About 20 minutes later, mission control erupted in cheers, hugs and tears when a signal from the craft indicated it was still functioning.
With that, NASA accomplished the most difficult part of its Martian adventure, landing the first of two twin robots on the red planet for the most ambitious scientific exploration of Earth's neighbour ever undertaken.
Second NASA rover
A second NASA rover, Opportunity, is scheduled to land on Mars on 25 January, on the opposite side of the planet.
"We're on Mars. It's an absolutely incredible accomplishment," said NASA administrator Sean O'Keefe, who poured champagne for the leaders of the mission team.
Spirit spent seven months travelling 500 million km through space to the red planet.
"We're on Mars. It's an absolutely incredible accomplishment"
The rover, cocooned by a cushion of giant air bags, had bounced across Mars' surface before coming to a rest.
NASA's triumph comes just days after the planned 25 December arrival of the ill-fated European robot Beagle 2, which has not been heard from since that date.
At a record cost of $820 million, the Mars mission will involve 250 NASA specialists and researchers who over three months will micro-manage the six-wheeled rovers, weighing 180 kilograms each, roughly the size of a subcompact car.