Phoenix probe lands safely on Mars

US SPACE scientists have successfully landed a $437 million spacecraft on Mars, after warning that the odds for success were less than 50 per cent.

The Phoenix probe touched down on the Martian surface shortly before 10am (AEST).

Scientists cheered at mission headquarters as they began picking up a signal from the probe, showing it had survived its fiery descent through the atmosphere on onto solid ground.
Phoenix entered the Martian atmosphere at about 21,000km/h and used a thermal shield, a parachute, then pulse thrusters to slow down to a mere 8km/h.

The entire process took about seven minutes - dubbed the "seven minutes of terror" by mission specialists.
Touchdown was on the circumpolar region known as Vastitas Borealis, akin to northern Canada in Earth's latitude.
Unlike previous Martian rover craft, Phoenix will spend the next 90 days digging into the planet's polar surface looking for signs of past life.
"I'm a little nervous on the inside. This is not an easy thing to do," scientist Peter Smith said before the Phoenix landed after its 679 million km journey from Earth.
Mission specialists reviewed data overnight to decide whether a course-correction would be needed to keep the Phoenix on track for landing in a relatively rock-free, flat region in the Mars arctic.
An earlier trajectory correction was scrubbed at the weekend because "Phoenix is so well on course", NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California, which controls the mission, said on its website.
The JPL ran a Phoenix blog with live updates from mission control. As the hours counted down, mission engineer Brent Shockley noted the "sleeping bags and cots scattered throughout offices and cubicles" as the team made final checks and crossed fingers.
Phoenix is the first spacecraft to land on the Martian arctic surface, digging into the polar ice lookinfg for evidence that flowing water might once have supported life.
"We are going to a place on the planet that is unexplored and very exciting," Mr Smith, Phoenix principal investigator at the University of Arizona, said over the weekend.
"Getting a scoop full of that icy soil is our goal" in searching for a habitable zone, he said.
But with the nearly five decades of Mars exploration fraught with failures - about half of the three dozen tries have crashed, disappeared or missed the planet altogether - there was little room for error.
"This is not a trip to grandma's house. Putting a spacecraft safely on Mars is hard and risky," Ed Weiler of NASA's Science Mission Directorate said.
NASA approved the mission after the Mars orbiter Odyssey found ice surrounding the polar caps in 2002. Five probes landed near Mars' equatorial zones, including the rovers Spirit and Opportunity, which discovered signs of past surface water.
Odyssey found no sign of buried ice around Mars' equator.
On Earth, the arctic regions hold the history of the planet's climate changes, which are locked layer by layer into the ice core.
"This is where the history of life is preserved in its purest form - organic molecules and cellular bacterial microbes and so forth," Mr Smith said.
"We'll leave future missions the task of figuring out who's living there."
Phoenix must now unfurl solar panels to allow it to catch energy from the Sun. If that process fails, a mission six years in the making will last just 31 hours - until Phoenix's batteries run out