Nasa probe blasts off for Mars

CAPE CANAVERAL, Florida - An Atlas 5 rocket has blasted off from Florida and dispatched a sophisticated Nasa probe on a journey to Mars to look for water on Earth's mysterious neighbour planet.

After two days of delays due to minor technical concerns, the 188-foot Atlas 5 booster, built by Lockheed Martin, blasted off its seaside launch pad at Cape Canaveral Air Force Station smoothly and on time.

Nestled in a protective cargo hold perched on the rocket's nose was the 2,180 kg Mars Reconnaissance Orbiter, also built by Lockheed Martin.

The rocket successfully placed the orbiter on a path to Mars.

Jubilant ground control teams shrieked with delight when the spacecraft successfully separated from the rocket's second-stage motor, unfurled its solar arrays and pivoted a communications antenna into position. The orbiter found targets for its star-tracker navigation system and responded to its first commands.

"We are at full control of a completely healthy spacecraft," said flight systems manager Howard Eisen.

The spacecraft's primary goal is to continue the search for evidence showing how long Mars had water, which scientists believe is key to learning if life ever existed on Mars.

When the satellite arrives at Mars it will join two other US orbiters, Mars Global Surveyor and Mars Odyssey, Europe's Mars Express spacecraft and the twin robot rovers, Spirit and Opportunity.

Those craft have found what may be signs of ancient coastlines and formations potentially carved by water.

The Mars Reconnaissance Orbiter is equipped with three high-resolution cameras and a radar sounder that can detect water and ice below Mars' surface.

It is to spend four years in orbit around Mars looking for spots to land future rovers and eventual human expeditions. Other instruments will be able to map surface minerals and monitor Mars' atmosphere.

POTENTIAL PITFALLS

Nasa's deputy associate administrator for science. Orlando Figueroa, congratulated the team on a successful launch but warned there were plenty of potential pitfalls ahead.

"We still have a long journey to Mars," Figueroa said.

The most trying moment will come in March when the orbiter must slow down and allow itself to be captured by Mars' gravity.

The engine burn to drop into Mars' orbit will take 30 minutes, half of which must be done with the planet in front of the probe, blocking communications with Earth. Nasa lost two Mars spacecraft in 1999 during failed entry attempts.

Flight engineers then must navigate the probe through six or seven months of adjustments to perfect the orbit for its scientific surveys.

The complement of cameras aboard the orbiter includes one with the largest-diameter telescopic lens ever sent to another planet.

Scientists have high hopes the camera will be able to snap pictures showing details as small as the width of an office desk.

"Every time we look with increased resolution, Mars has said, 'Here's something you didn't expect. You don't understand me yet,"' said project scientist Richard Zurek of Nasa's Jet Propulsion Laboratory in Pasadena, California.

The craft is capable of transmitting data back to Earth 10 times faster than previous Mars probes. It also is intended to serve as the communications relay station for a rover scheduled to launch in 2007 and a science laboratory targeted for launch in 2009.

"Wait until you see the science that is going to come back from this mission. It's going to know your socks off," Eisen said.

- REUTERS