US mission lands safely on Mars

[Salem6]

A Nasa space probe has landed on Mars to seek signs that the planet was once capable of supporting life.

The six-wheeled rover Spirit parachuted on to the planet's surface at about 0435 GMT on Sunday.


The first images of Mars are relayed to the control room

The robotic spacecraft has already sent back historic images of the rocky landscape where it bounced to rest.

It will explore a crater that may once have held a lake in a three-month mission to examine rocks and search for water.

The six-minute descent to the surface was the final and most daunting leg of the seven-month voyage from Earth.

In the past, two out of three attempts to land spacecraft on the Red Planet have failed.

The European Space Agency is still searching for the missing British-built Beagle 2.

The probe was supposed to land on Mars on Christmas Day but has not yet sent back a signal to confirm it has arrived safely.

Tense wait

Such are the risks of landing on Mars that Nasa had installed a system on the rover to send back information about the descent.


Nasa chief Sean O'Keefe: 'We're on Mars'

The landing sequence took the spacecraft from 19,000 km/h (12,000 mph) to a complete stop in six minutes.

A series of tones picked up by telescopes on Earth signalled that the vehicle's parachute and landing airbags had deployed properly.

Mission controllers at Nasa's Jet Propulsion Laboratory (JPL) in Pasadena, California, smiled and cheered as the news came in.

After a nervous wait of about 20 minutes they received a radio signal from the rover confirming it was functioning after bouncing to a halt on the Martian surface.

Nasa chief Sean O'Keefe congratulated mission officials while scientists jumped up-and-down in jubilation.

"This is a big night for Nasa - we are back!" he said at a triumphant news conference. "I'm very, very proud of this team and we're on Mars. It's an absolutely incredible accomplishment."

Field geologists

Spirit is one of a pair of rovers that will seek evidence for water on Mars.

US MARS ROVERS

Spirit targeted at Gusev Crater, possible ancient lake feature
Opportunity to land at Meridiani Planum, which contains minerals often associated with water
Spirit and Opportunity weigh about 17 times as much as the 1997 Sojourner rover


Its twin, Opportunity, will touch down on the other side of Mars in late January.

The £545m rovers will roam the planet and examine rocks in a three-month mission to map out the history of water on Mars.

Mission scientist Dr Steve Squyers, from Cornell University in New York, said Spirit and Opportunity will act as robotic field geologists.

"They look around with a stereo, colour camera and with an infrared instrument that can classify rock types from a distance," he said.

"They go to the rocks that seem most interesting. When they get to one, they reach out with a robotic arm that has a handful of tools, a microscope, two instruments for identifying what the rock is made of, and a grinder for getting to a fresh, unweathered surface inside the rock."

Spirit will explore the Gusev Crater, just south of the Martian equator, which may once have held a lake.

First it will spend a week or more scanning its surroundings and carrying out engineering checks.

Then it will roll off its lander and start trundling over the surface of Mars.



Video:-


The BBC's Christine McGourty
"The quality and the number of images so soon after landing was more than the team had hoped for"
news.bbc.co.uk/media/video/39699000/rm/_39699387_mars09_mcgourty_vi.ram

[Salem6]

The first US rover - called Spirit - landed on at Mars at about 0435 GMT on Sunday. The "robotic geologist" will be followed down in late January by its twin, Opportunity.


Nasa's robotic explorers will roam Mars looking for signs of water




Their mission is to examine their landing sites for past environmental conditions that may have been conducive to life.

Dr Steve Squyres, of Cornell University, is principal investigator for the suite of science tools on each rover.

How do Spirit and Opportunity differ from the first Mars rover?

They are much larger and much more capable. The rover that flew to Mars in 1996-7 on the Mars Pathfinder mission was really just an engineering demonstration vehicle; it didn't have much of a science payload on it or the capability to go very far from its lander. It never got more than about 10 or 20 metres away from its lander.

This time we are flying a much, much larger vehicle. It's more than 180 kg in weight. It's able to travel tens of metres in a day across the Martian surface and it carries an entire suite of scientific instruments with it. It's a real robotic explorer.

What are Spirit and Opportunity going to be looking for?

The purpose of the mission is to try to find out whether or not Mars was once the kind of place that could have supported life. Mars is a really cold, dry, miserable place today. It is not an environment at its surface that is very well suited to life.


ROVING 'FIELD GEOLOGISTS'
Spirit targeted at Gusev Crater, possible ancient lake feature
Opportunity to land at Meridiani Planum, which contains minerals often associated with water
Spirit and Opportunity weigh about 17 times as much as the 1997 Sojourner rover
Both carry cameras and tools to grind and analyse rocks

And yet when we look down from orbit with cameras and spectrometers we see tantalising clues that it used to be different. We see dried up river beds, we see dried up lake beds, we see the kinds of minerals that one might find in a hot-spring environment.

We're trying to go to two places where we think it might have been warmer and wetter and more Earth-like in the past and to try to read the geologic clues there and see if these really were places that would have been suitable for life.

And to look if there is still life there?

No. We're not actually looking specifically for life. What we are doing is looking for evidence that life could have been supported. This is not a life search or life detection mission.


Spirit left Earth on its Delta rocket back in June


Why do probes to Mars have such a high failure rate?

It's an incredibly long distance away. Landing in particular is very, very hard because you are going into a very poorly known environment. We don't yet have the technology to do a controlled landing at a pinpoint location on the Martian surface.

So at the moment you just plummet towards the surface into what could be a rock field or some other type of terrain. You have got to design a vehicle that can withstand anything it might hit, any environment it might run in to. It's not surprising that there have been a significant number of failures.

Is there anything you can learn from the Beagle experience?

The two vehicles are very different and so I'm not sure there is much we can learn from their experience. It is hard to tell what has happened to Beagle and it will be until Colin Pillinger and his team hear from their spacecraft.

And there is no opportunity to look for Beagle 2?

No. We're going to two very different places. The landing sites we've picked are quite far from the Isidis Planitia site where Beagle landed.

Presumably you are still learning so whatever happens with Spirit you can still modify Opportunity to help it?

Yes. We hope so. If we saw some unexpected events during the final descent of Spirit towards the surface, we could do some last-minute reprogramming of some aspects of the way Opportunity would land.






Historic landing
The US space agency (Nasa) made history in 1976, when its two Viking landers touched down on the Martian soil. The probes carried biology experiments to look for signs of life but no conclusive evidence was found. The debate rumbles on, bolstered by geological data suggesting Mars was once a watery world of rivers, lakes and oceans.


Blazing a trail
It would be another 21 years before Mars Pathfinder explored an ancient flood plain just north of the Martian equator in July 1997. The lander was equipped with scientific instruments for examining rocks and soil. It also released the first mobile robotic rover to explore the surface of Mars. The tiny rover, named Sojourner, was able to roam around the landing site studying rocks.


Robot explorers
Pathfinder's micro-rover Sojourner paved the way for Nasa’s powerful new robot explorers, set for launch in June 2003. Like Sojourner, the Mars Exploration Rovers are mounted on wheels and can go on sortees of the local terrain. They are much bigger than Sojourner – about the size of a quad bike and weighing 180 kg – and will be able to explore up to 10 times further.


Field geologists
The robots will act as roving geologists, examining rocks with cameras, a microscope and spectrometers. They are looking for chemical signatures in rock that show water once existed on the surface of Mars. Unlike the mini Sojourner rover, the new generation rovers will carry all their instruments with them. They can be commanded to go to rock and soil sites of interest by scientists on Earth.


Launch
The twin rovers, named Spirit and Opportunity, are being blasted into space on Delta II rockets from Cape Canaveral in Florida. They are being launched separately, in June. The space craft are due to arrive at Mars in January. Each rover, stowed inside a lander, will descend to the surface of Mars on a parachute.


Landing sites
The rovers are heading for different sides of the Red Planet to search for water. Spirit will visit the ancient Gusev crater in the Martian tropics that may once have been a lake. Opportunity is going to another place that holds promise of water, a flat plain known as Meridiani Planum that may once have been flooded or peppered by hot springs.


Video:-

The BBC's Christine McGourty
"The aim is to look for any sign there was once water here and possibly life"
news.bbc.co.uk/media/video/39697000/rm/_39697039_mars06_mcgourty_vi.ram