Man 'decade away' from Mars

Mankind could be a decade away from walking on Mars, a Nasa scientist has said.

"If we had the motive, if it was important enough, I would say within 10 years we could be there," said Adam Steltzner, the lead mechanical engineer for the entry.

Steltzner was speaking ahead of yesterday's dramatic landing on the Red Planet by Nasa's science rover Curiosity.

"Putting men on Mars is achievable. It is just really hard and expensive," Steltzner said.

"So if the world were to find itself with enough resources and the motivation, we could do it."

Curiosity performed a daredevil descent late on Sunday to clinch an historic landing early yesterday inside an ancient crater, ready to search for signs that the Red Planet may once have harboured key ingredients for life.

Mission controllers burst into applause and cheers as they received signals confirming that the car-sized rover had survived a perilous seven-minute descent Nasa called the most elaborate and difficult feat in the annals of robotic spaceflight.

Engineers said the tricky landing sequence, combining a giant parachute with a rocket-pack that lowered the rover to the pink Martian surface on a tether, allowed for zero margin for error.

Moments later, Curiosity beamed back its first three images from the Martian surface, one of them showing a wheel of the vehicle and the rover's shadow cast on the rocky terrain.

Nasa put the official landing time of Curiosity, touted as the first full-fledged mobile science laboratory sent to a distant world, at 7.30am. The landing marked a welcome success and a major milestone for a US space agency beset by budget cuts and the recent cancellation of its space shuttle programme, Nasa's centrepiece for 30 years.

The $2.5-billion Curiosity project, formally called the Mars Science Laboratory, is the space agency's first astrobiology mission since the 1970s-era Viking probes.

"It is an enormous step forward in planetary exploration. Nobody has ever done anything like this," said John Holdren, the top science adviser to President Barack Obama.

Obama issued a statement hailing the Curiosity landing as "an unprecedented feat of technology that will stand as a point of national pride far into the future".

Nasa plans to put the one-ton, six-wheeled, nuclear-powered rover and its sophisticated instruments through several weeks of engineering checks before starting its two-year surface mission in earnest.

The rover's precise location had yet to be determined, but Nasa said it came to rest in its planned landing zone near the foot of a tall mountain rising from the floor of a vast impact basin called Gale Crater, in Mars' southern hemisphere.

Launched on November 26 from Cape Canaveral in Florida, the robotic lab sailed through space for more than eight months, covering 566million kilometres, before piercing Mars' thin atmosphere at 120921km/h - 17 times the speed of sound - and starting its descent.

Encased in a protective capsule-like shell, the craft utilised a first-of-its kind automated flight-entry system to sharply reduce its speed. Then the probe rode a huge, supersonic parachute into the lower atmosphere before a jet-powered backpack Nasa called a "sky crane" carried Curiosity to its destination, lowering it to the ground by nylon tethers.

When the rover's wheels were planted firmly on the ground, the cords were cut and the sky crane flew a safe distance away and crashed.

The sequence involved 79 pyrotechnic detonations to release exterior ballast weights, open the parachute, separate the heat shield, detach the craft's back shell, jettison the parachute and other functions.

Curiosity weighed too much to be bounced to the surface in airbags or fly itself all the way down with rocket thrusters - systemssuccessfully used by six previous Nasa landers, engineers said.

Curiosity is designed to spend the next two years exploring Gale Crater and a 5km high mountain consisting of what appears to be sediments rising from the crater's floor.

Its primary mission is to look for evidence that Mars - the planet most similar to Earth - may have once hosted the basic building blocks necessary for microbial life to evolve.