NASA rover signal sent to Earth after landing on Mars

PASADENA, Calif. -- A NASA rover plunged through the atmosphere of Mars and bounced down upon its rocky surface Saturday night, beginning a mission to roam the Red Planet in search of evidence that it was once suitable for life.

A cheer went up at NASA's Jet Propulsion Laboratory after signals showed the spacecraft had successfully reached Mars.

The rover signaled Earth after landing.

The spacecraft successfully separated from its cruise stage late Saturday, freeing the unmanned probe to plunge into the atmosphere of Mars for the fiery trip to the surface of the planet.

The separation took place at 11:14 p.m. EST, about 20 minutes before the Spirit rover's highly anticipated landing on Mars. NASA warned that communications with the spacecraft carrying the six-wheeled robot would be spotty during its descent.

Confirmation of a safe landing could take as little as 10 minutes, or as long as 24 hours, NASA said earlier.

About an hour before separating, the spacecraft made an 18-minute maneuver to turn toward Mars.

The Spirit rover is the first of two identical robots that will roam the planet's rocky surface if all goes as planned.

The gravity of Mars had already begun to tug on the spacecraft earlier Saturday from a distance of 59,000 miles, project manager Pete Theisinger said.

Spirit had been on track to make a "bull's-eye" landing within a cigar-shaped ellipse inside Gusev Crater, a Connecticut-sized indentation just south of the Martian equator, navigation team chief Louis D'Amario said.

"This is essentially perfect navigation. We couldn't have possibly hoped to do better than this," D'Amario said.

Previously, about two of every three attempts to land spacecraft on Mars have failed. The latest apparent failure was the British Beagle 2 lander, which has not been heard from since it was to have set down on Mars on Christmas.

"It's an incredibly difficult place to land. Some have called it the 'death planet' for good reason," said Ed Weiler, NASA's associate administrator for space science.

1999 attempt

NASA's last attempt at landing on Mars, in 1999, failed when a software glitch sent the Polar Lander crashing to the ground. Since then, the space agency has increased oversight of its missions.

"We have done everything we know to do to ensure these missions will be a success," said Charles Elachi, director of the National Aeronautics and Space Administration's Jet Propulsion Laboratory.

The $820 million NASA project also includes a twin rover, Opportunity, which is set to arrive on Mars on Jan. 24.

The camera- and instrument-laden rovers were designed to spend 90 days analyzing Martian rocks and soil for clues that could reveal whether the Red Planet was ever a warmer, wetter place capable of sustaining life.

Today, Mars is a dry and cold world. But ancient river channels and other water-carved features spied from orbit suggest that Mars may have had a more hospitable past.

"We see these intriguing hints Mars may have been a different place long ago," Squyres said.

The rovers were built to look for evidence that liquid water -- a necessary ingredient for life -- once persisted on the surface of the planet. A direct search for life on Mars is at least a decade away, NASA scientists said.

Together, the twin robots were launched in the most intensive scientific assault on another planetary body since the Apollo missions to the moon, said Orlando Figueroa, director of NASA's Mars exploration program.

NASA launched the 384-pound Spirit and its twin in hopes they would become the fourth and fifth U.S. spacecraft to survive landing on Mars. Twenty other spacecraft from various nations have failed.

Scientists are taking advantage of the closest approach Mars has made to Earth in 60,000 years. NASA intends to send spacecraft to Mars at regular 26-month intervals, or each time the Earth laps the Red Planet as they both circle the sun.

The highly anticipated Spirit landing follows another important American space mission. On Friday, a NASA spacecraft flew through the bright halo of a distant comet to scoop up less than a thimbleful of dust that could shed light on how the solar system was formed.