Soon after NASA's Phoenix space probe landed safely Sunday on tundra above the Martian arctic circle, the first images of the red planet began streaming to Earth, dpa reported.
Scientists began examining a site within reach of the lander's 2.4-metre robotic arm that was chosen for its likelihood to have ice, which could hold clues to whether life has ever existed on Mars.
Images from the Phoenix lander provided a look at a flat valley floor, where scientists expected to find a water-rich permafrost within reach of the robotic arm, the beginning of a three-month research mission to sample soil and ice in the polar region.
"We see the lack of rocks that we expected, we see the polygons that we saw from space, we don't see ice on the surface, but we think we will see it beneath the surface," said Peter Smith of the University of Arizona, principal investigator for the Phoenix mission. "It looks great to me."
The scene at NASA's Jet Propulsion Laboratory (JPL) mission control in Pasadena, California, was punctuated by hoots and high fives as the probe achieved key milestones, leading up to the successful touchdown Sunday, confirmed by radio transmission.
Radio signals from the lander take more than 15 minutes to travel at the speed of light from Mars to Earth.
Landing on three legs, the arrival was the first first successful Mars landing without airbags since Viking 2 in 1976.
After landing, the robotic Mars probe ran on batteries until its pair of solar arrays spread open as planned about two hours after touchdown.
Continued success of the Mars mission, which began with a 680- million-kilometre flight from Earth after launching on August 4, 2007, depends on the solar energy supply.
The team said a stereo camera and a weather station are in position and functional, important signs of fully functional spacecraft.
The first pictures delivered from Mars confirmed that the solar arrays had unfolded properly.
"Seeing these images after a successful landing reaffirmed the thorough work over the past five years by a great team," said JPL's Barry Goldstein, the Phoenix project manager.