NASA's Phoenix Mars probe on track

Washington - NASA's Phoenix space probe landed safely Sunday on tundra above the Martian arctic circle. Mission control members Eric DeJohn (L) and Ed Sedivy (R) view images downlinked from the Phoenix Mars Lander to the control room at NASA's Jet Propulsion Laboratory in Pasadena, California, USA, 25 May 2008. The Phoenix mission will study the history of water in the Martian arctic and to search for evidence of a habitable zone. EPA/MARK TERRELL/POOL

Mission control members Eric DeJohn (L) and Ed Sedivy (R) view images downlinked from the Phoenix Mars Lander to the control room at NASA's Jet Propulsion Laboratory in Pasadena, California, USA, 25 May 2008. The Phoenix mission will study the history of water in the Martian arctic and to search for evidence of a habitable zone. EPA/MARK TERRELL/POOLScientists will begin examining a site within reach of the lander's robotic arm that was chosen for its likelihood to have ice. 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 confirmed by radio transmission. Radio signals received at 2353 GMT confirmed the Mars lander had survived final descent and touchdown 15 minutes earlier. The signals took that long to travel from Mars to Earth at the speed of light. Critical to a successful landing, a parachute was deployed about 12.5 kilometres above the surface of Mars as the aircraft was traveling 1.7 times the speed of sound when it entered the Martian atmosphere. Landing on three legs, the arrival was the first first successful Mars landing without airbags since Viking 2 in 1976. 'For the first time in 32 years, and only the third time in history, a JPL team has carried out a soft landing on Mars,' NASA administrator Michael Griffin said. 'I couldn't be happier to be here to witness this incredible achievement.' The robotic probe landed on tundra above the Martian arctic circle, a terrain never before explored, NASA scientists said. The mission on Mars hopes to uncover mysteries about water on the frozen planet. Continued success of the Mars mission, which began with a 680- million-kilometre flight from Earth after launching on August 4, 2007, depends on solar power yet to be brought online. Phoenix relied on electricity from solar panels during the spacecraft's journey through space, NASA said. The infrastructure was jettisoned seven minutes before the lander, encased in a protective shell, entered the Martian atmosphere. The lander is running on batteries until it's pair of solar arrays spread open. 'We've passed the hardest part, and we're breathing again, but we still need to see that Phoenix has opened its solar arrays and begun generating power,' said JPL's Barry Goldstein, the Phoenix project manager. Engineers expected to learn the status of the solar arrays overnight Sunday from a Phoenix transmission relayed via NASA's Mars Odyssey orbiter. The team hopes to learn from the transmission whether a stereo camera and a weather station are in position and functional, which will be important signs of fully functional spacecraft. 'What a thrilling landing,' said Peter Smith of the University of Arizona, principal investigator for the Phoenix mission. 'I can hardly contain my enthusiasm. The first landed images of the Martian polar terrain will set the stage for our mission.' As the lander's systems list is checked off, the key signal of success will be deployment of the 2.3-foot-long robotic arm on Phoenix, which researchers will use in coming weeks to gather samples of soil and ice, which could reveal past or current life on Mars.