The $820 million mission's scientific director, Steve Squyres, was left gasping for words as Opportunity sent back to Earth pictures of what he described as an "alien landscape".

"I am flabbergasted, I'm astonished, I'm blown away," the 47-year-old scientist said at the National Aeronautic and Space Administration's Jet Propulsion Laboratory in California.

The pictures enlivened scientists who continued working to repair the mission's first robotic probe, Spirit, which started communicating with NASA again on Friday, two days after a worrisome communications breakdown.

Rock outcrop

"I am flabbergasted, I'm astonished, I'm blown away. Opportunity has touched down in a bizarre, alien landscape"

Steve Squyres,
Scientist

Opportunity's black-and-white and colour pictures showed that it landed near a rock outcropping that seemed very promising to geologists in the Mars Exploration Rover mission.

"This is the first rock outcrop ever found on Mars," Squyres, a professor at Cornell University in New York state, said in a news conference during which he was visibly excited.

"Opportunity has touched down in a bizarre, alien landscape."

The rock outcropping is scientifically invaluable because, unlike stones that can come from elsewhere, they are historically linked to their location, he said.

To Squyres, who conceived the idea for the mission in 1987, the rover's success is the culmination of 16 years of work.

In 2000, NASA picked him to lead the mission's scientists and to choose the instruments the rovers would need.

"It was exactly what it was in my wildest dream," said Squyres, who heads a group of more than 180 researchers.

Safe landing

An image taken by Opportunity's
panoramic camera

Opportunity landed safely on Mars at 0505 GMT on Saturday in a small crater in an area known as the Meridiani Planum, and approaching the nearby rock outcropping will be one of the rover's first objectives.

"We are lucky," said Larry Soderblom, of the US Geological Survey, calling the mission a "scientific jackpot".

"It is difficult to find a place safe enough to land and expecting to find something interesting when you get there," he said.

The Meridiani Planum is a zone of grey hematite, an iron oxide.

Scientists plan to use the robot's instruments to determine whether the grey hematite layer comes from sediments of a former ocean, from volcanic deposits altered by hot water or from other ancient environmental conditions.

Mine of information

"We could spend most of the mission just in this little crater," the mission's scientific director Steve Squyres said at NASA's Jet Propulsion Laboratory.

Unlike the area where Opportunity's twin probe Spirit landed, the rocks in Opportunity's neighbourhood were formed where they lie, giving scientists a chance to try to unravel the planet's geologic history.

Spirit, which landed on 3 January but broke down last week, remains "serious," said its mission chief Pete Theisinger.

"We are kind of on the way to a normal recovery. I think we have a very good chance that we will have a very good rover. Once again, it will take some time to make sure that we have completely characterised the problem."