A NASA probe was poised to make a "bull's-eye" landing in a Martian crater today, said project leaders hopeful the spacecraft will safely deliver an unmanned rover and buck a trend of failed missions to the Red Planet.

The Mars Exploration Rover, Spirit, developed by the NASA's Jet Propulsion Laboratory in Pasadena, California, descends to the Martian encased in a set of inflatable balloons protecting the spacecraft, after the initial parachute was jettisoned, in this undated artist's drawing released by NASA. [AP]

The spacecraft was expected to reach Mars on Sunday (Beijing Time) with the Spirit rover, the first of two identical six-wheeled 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 appeared 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.

NASA could hear from Spirit within 10 minutes of landing, but it's more likely that first word that it's arrived would come in the early morning hours Sunday, Theisinger said. Spotty communications could delay confirmation of a safe landing - and transmission of the rover's first pictures - for up to 24 hours.

"It could be a long wait," said Steve Squyres, the mission's main scientist.

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.

Close

Today's Top News		Top International News
+Patient may be infected with SARS variation ( 2004-01-03) +HK confirms 3 imported food poisoning outbreaks ( 2004-01-04) +Safety supervision teams sent out across country ( 2004-01-04) +China praised on suspected SARS response ( 2004-01-03) +Virus variation found in suspected SARS case ( 2004-01-02)		+NASA spacecraft heads toward Mars landing ( 2004-01-04) +Nigeria says it has put down Islamic sect ( 2004-01-04) +Egyptian charter jet crashes, killing 148 ( 2004-01-04) +UK warns of more flight disruption in terror war ( 2004-01-04) +Hopes raised for India-Pakistan relations ( 2004-01-04)