Nasa space craft lands on Mars
Nasa's robotic space craft Curiosity has landed on Mars.
The six-wheeled nuclear-powered vehicle, carrying 10 scientific instruments, was lowered to the Martian surface on three nylon tethers suspended from a hovering sky crane kept airborne with retro rockets shortly after 6.30am.
Mission controllers burst into applause and cheered in relief as they received signals confirming that the rover had survived its perilous descent and arrived within its target zone at the bottom of a vast, ancient crater.
The robotic lab sailed through space for more than eight months, covering 566 million km, before piercing Mars' atmosphere at 20,921km per hour - 17 times the speed of sound - before starting its descent.
Moments after landing, 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.
One of the first pictures sent back from Mars by Curiosity.
"I can't believe this. This is unbelievable," enthused Allen Chen, the deputy lead of the rover's entry, descent and landing team at the Jet Propulsion Laboratory near Los Angeles.
The craft's descent through Mars' thin atmosphere, a feat called the most elaborate and risky achievement in the annals of robotic spaceflight, turned out to be short-lived cliff-hanger, much to Nasa's relief.
Curiosity, encased in a protective capsule-like shell, utilised a first-of-its kind automated flight entry system to sharply reduce its speed before landing.
Then it rode a giant supersonic parachute, a jet-powered backpack and a never-before-used sky crane to touch down inside a vast impact basin called Gale Crater, located near the planet's equator in its southern hemisphere.
Nasa put the official landing time of Curiosity, the first full-fledged mobile science laboratory sent to a distant world, at 6.30am.
Curiosity will spend two years exploring Gale Crater and an unusual 5 km-high mountain consisting of what appears to be sediments rising from the crater's floor.
The purpose of the $2.5 billion mission is to look for evidence that Mars - the planet most similar to Earth - may have once harboured the basic building blocks necessary for microbial life to evolve. It represents Nasa's first astrobiology mission since the 1970s-era Viking probes.
The landing marks a major milestone for a US space agency beset by budget cuts and the recent loss of its 30-year-old space shuttle program.
"It's an enormous step forward in planetary exploration. Nobody has ever done anything like this," said John Holdren, the top science advisor to president Barack Obama, who was visiting JPL for the event. "It was an incredible performance."
The exact condition of the rover upon arrival was not immediately clear. Nasa plans to put the rover and its laboratory gear through several weeks of engineering checks before starting its two-year surface mission in earnest.
The rover, launched on November 26th from Cape Canaveral, Florida, comes equipped with an array of sophisticated instruments capable of analyzing samples of soil, rocks and atmosphere on the spot and beaming results back to Earth.
One is a laser gun that can zap a rock from seven metres away to create a spark whose spectral image is analyzed by a special telescope to discern the mineral's chemical composition.