WASHINGTON (AFP) - - NASA's Phoenix spacecraft successfully landed on Mars' frigid north pole region in a risk-fraught mission to search for signs the planet could have supported life, the US space agency said.

"Phoenix has landed," a NASA official said as the safe touchdown was confirmed.

The Mars Phoenix Lander successfully deployed a parachute and then thrusters to brake in a tense seven minutes from 20,400 kilometers per hour (12,700 miles per hour) to manage a soft landing on its three legs.

Mission officials at the Jet Propulsion Laboratory (JPL) in Pasadena, California, were seen on television cheering and giving each other hugs and high-fives after signals sent back from the craft confirmed the arrival of the first spacecraft ever to land on the Martian arctic.

The 420-million-dollar spacecraft is designed to help scientists assess whether the Martian arctic has ever had conditions favorable to microbial life.

Given that Mars ' polar region is subject to Earth-like seasonal changes, the scientists are looking to see whether there is a point where the region warms and changes into a water-rich soil with organic, life-supporting minerals.

"Our whole mission is about digging," said Peter Smith, Phoenix principal investigator at the University of Arizona.

"We find that the arctic region is really sensitive to climate change on a planet ... it also preserves the history of life," Smith said.

"We think that organics must have existed at least at one time" from meteorite and other impacts, he said. The presence of liquid water and organics would signify a "habitable zone," he said.

Phoenix managed an almost perfect landing in a relatively rock-free, flat target area in the flat circumpolar region known as Vastitas Borealis -- akin to northern Canada in Earth's latitude, according to Barry Goldstein, Phoenix project manager at JPL.

The team had been worried about the high risk of the project, with a roughly 50 percent failure rate on all Mars missions since the Russians launched the first one in 1960.

"Frankly, this was by far the hardest part," Goldstein said on NASA TV. "In my dreams it couldn't have gone as perfectly as it did tonight."

NASA will only know that the landing and deployment of Phoenix's equipment went well after pictures from the probe reach the Earth via NASA's Odyssey Mars orbiter, two hours after the landing.

The first pictures will be of the craft itself, to show NASA if all the equipment deployed in working order, and then, possibly shots of the surface.

Phoenix is equipped with a camera and a 2.35-meter (7.7-foot) robotic arm that can dig as deep as one meter to find ice, and can heat up samples to detect carbon and hydrogen molecules, essential elements of life.

It also has meteorological equipment to study the Mars atmosphere.