Second US Mars rover takes its opportunity

PASADENA - The Opportunity space craft has landed on the surface of Mars, Nasa engineers at the jet propulsion laboratory said last night.

At 5pm engineers received a signal that Opportunity had touched down on the Meridiani Planum, a smooth plain near Mars' equator on the other side of the Red Planet from its twin rover, Spirit.

"We are on Mars, everybody," said Wayne Lee, the entry, descent and landing specialist, after scientists received a signal from Opportunity when the airbag-encased spacecraft began bouncing on the surface.

The lander shot through the Martian atmosphere in what appeared to be a flawless six-minute sequence, exactly like Spirit's landing about three weeks ago.

Nine minutes after landing, there was evidence that the spacecraft was still rolling gently, which was not unexpected because the plain is very flat.

Meanwhile, scientists said the Mars Spirit rover was responding to commands and would be back to full operation within a couple of weeks.

"I am completely confident, without any hesitation, that I think we will get that rover back to full operation," said Charles Elachi, director of the Jet Propulsion Laboratory, which runs the Mars mission.

He estimated it would take several days to a few weeks for the recovery.

Scientists found a possible flaw in the spacecraft's computer memory and put it in "cripple mode".

That was good enough to upgrade the rover's status from critical to serious. The six-wheeled craft had a communications breakdown on Thursday, less than a week after successfully rolling off its landing platform to begin searching for signs of life-supporting water.

"We got control of the vehicle back; we got power, good comm [communications]; we can deal with it," said Mars Exploration Rover project manager Pete Theisinger.

Spirit had been put to sleep and was to wake up again shortly after its twin landed.

Opportunity slowed from about 5.4km a second to a standstill in six minutes as it burned through the atmosphere, deployed a parachute, fired retrorockets to come to a hover above the surface, and then dropped the final 13m or so to the surface, swathed in a cocoon of airbags that protected it while it rolled to a halt.

Opportunity's target area, Meridiani Planum, is believed to be full of iron-bearing hematite, a mineral that on Earth usually forms in the presence of water.

Spirit's flash memory chips, the same storage medium used by digital cameras on earth, or software that works with the flash, appeared to be malfunctioning, Theisinger said.

The flash memory on Spirit also holds pictures and scientific data.

Once they found the probable source of the spacecraft's confusion, scientists told Spirit to ignore the flash memory and go into "cripple mode".

That allowed Spirit to shut down, ending the cycle of computer resets - around 130 since it began to malfunction - which drained the batteries of the lander.

The sun's rays will power up Spirit's solar array and wake up the rover after sunrise on Gusev Crater, where the lander is stranded.

Scientists will then tell it to go back into cripple mode and try to establish a better communications link.

They are already looking at ways to use other types of computer memory on board and to pinpoint the problem.

Nasa associate administrator for space sciences Ed Weiler said he expected Spirit to extend its three-month mission, which began about three weeks ago, for a number of months and that the six-wheeler would hit the road again.

"I think we are probably three weeks away from driving," Theisinger said.


- REUTERS