Mars orbiter reaches Red Planet
Nasa`s Mars Reconnaissance Orbiter (MRO) has survived a critical phase in its mission by parking itself in an elliptical orbit around the Red Planet. News of its success followed a tense period of radio silence while the spacecraft passed behind Mars.
Over the next six months, the probe will steadily reduce the size of its orbit until it reaches an optimal position to start scientific studies.
MRO will examine the Martian surface and atmosphere in unprecedented detail.
At 2124 GMT (1334 PST), as the spacecraft approached the south-side of the planet, its engines fired, slowing its speed and allowing it to be captured by Mars` gravity.
About 20 minutes later, MRO switched from solar to battery power as it passed behind the planet and entered into a period of radio silence.
The re-establishment of contact half an hour later was met with great relief from the mission team at the US space agency`s (Nasa) Jet Propulsion Laboratory, in Pasadena, California.
"Mars has taught us never to get overconfident. Two of the last four orbiters Nasa sent to Mars did not survive final approach," Jim Graf, MRO project manager, said before the orbit-insertion manoeuvre. "Mars is unpredictable."
The probe has joined three other satellites around the Red Planet: Nasa`s Mars Global Surveyor and Mars Odyssey, and the European Space Agency`s Mars Express.
MRO is now in a 35-hour elliptical trajectory around Mars, where at its furthest point it will swing out to about 44,000km (27,000 miles) above the planet`s surface.
The next phase for the mission will be to slowly shrink the spacecraft`s path around the world until it achieves a tight, circular, two-hour orbit.
This process will take six months, and employs a technique known as aerobraking, whereby the spacecraft slows itself down by using the friction created each time it brushes past the Martian atmosphere.
"It uses the air resistance against the solar panels to slow it down. And as it slows down over the next six months, it will get closer and closer to Mars," observed Professor Colin Pillinger, who led the UK`s failed Beagle 2 mission to Mars in 2003.
The orbiter will have to perform this technique over 500 times; however, Professor Pillinger said, each manoeuvre was perilous.
"If it goes in [the planet`s atmosphere] to far it heats up and crashes and burns. If it hits the atmosphere at the wrong speed, it bounces off and goes off into deep space," he said.
In November 2006, once the orbiter is in the optimal position, the two-year science phase of the mission will commence.
The spacecraft carries a pay-load of six scientific instruments, and will send back a wealth of information about the planet.
It will study the planet`s climate, look at water-containing minerals, and probe beneath the Martian surface searching for ice.
The orbiter also has cameras on board that will be able to take close-up images of the planet`s surface.
"Previous orbiters could see something the size of a double-decker bus on the surface of Mars - this can see a dinner table," said Dr Matthew Genge, of Imperial College, London.
"So that means we can see things like a small spring of hot water coming out of the ground, if such a thing exists. It will also be able to see things like large rocks that may be a hazard to other landers that in the future will want to land on Mars."
The Nasa mission team says that MRO will return 10-times more data than all of the previous Mars missions put together.
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