May 25, 2008
Phoenix Lands Safely and Transmits First Images
NASA's Phoenix Lander settled onto the frozen plains surrounding the unexplored Martian north pole on Sunday, ending a 10-month journey from Earth with a harrowing descent, slowed by parachute and braking rockets.
Signals confirming the three-legged spacecraft's arrival reached NASA's Jet Propulsion Laboratory at 6:53 p.m. CDT, unleashing a chorus of cheers and hugs from an anxious squad of flight controllers.
"Touchdown confirmed. Phoenix has landed," said Richard Kornfeld, lead communications officer for the spacecraft's NASA landing team. "Welcome to the northern plains of Mars."
Signals heralding Phoenix's arrival were relayed to Earth through NASA's Mars Odyssey, a spacecraft circling the Red Planet.
Though parked on Mars in one piece, the lander faced a checklist of actions while the relay satellite was out of contact. Each was crucial to the spacecraft's survival and the science mission.
Odyssey was to pass over Phoenix again late Sunday, collecting a self-portrait that would reveal whether the lander was positioned upright and had fully unfurled a pair of circular, electricity-generating solar panels.
Others already there
Phoenix joined a growing armada of international spacecraft at the Red Planet, including NASA's rovers Spirit and Opportunity, which have been exploring an older rocky terrain closer to the Martian equator since their arrivals in January 2004. NASA's Mars Reconnaissance Orbiter and the European Mars Express circle the planet with Odyssey.
Phoenix carried seven scientific instruments, including an 8-foot-long robot arm equipped to dig like a backhoe, mini-chemistry labs, cameras and a weather station.
If the checkout goes well, Phoenix could flex its arm for the first time on Tuesday. The craft could take the first soil sample in about two weeks.
Peter Smith, the University of Arizona physicist who serves as the mission's chief scientist, will lead the digging and analysis of the planet's soil from a lab at the Tucson school.
Phoenix is equipped to analyze up to eight soil and ice samples in small single-use ovens on the spacecraft. Another lab will mix four samples of soil in tiny containers of water. The lab activities are intended to reveal the presence of "organics," or carbon-based molecules that are considered to be the chemical building blocks of life.
Scientists plan to dig progressively deeper into the soil, perhaps down as much as 20 inches.
The methodical soil studies could unfold over three months.
Phoenix reached Mars on a trajectory so accurate that mission managers decided late Saturday to skip an opportunity for a final corrective maneuver.
As the spacecraft neared its destination, the pull of Martian gravity increased. The lander's velocity more than doubled, reaching 12,600 miles per hour before it plunged into the thin Martian atmosphere.
Temperatures around the probe soared to 2,600 degrees as it slowed, shedding a protective shell. As the velocity slowed, the temperatures cooled.
During a the final four minutes, Phoenix deployed a parachute, cast off a heat shield and lowered lander legs.
A dozen braking rockets ignited during the final 30 seconds of flight, slowing the descending spacecraft to 5 mph before it touched down.
Phoenix became only the sixth spacecraft to touch down safely on Mars and the first to do so using parachutes and braking rockets since the 1976 landings by the Viking I and Viking II landers.
NASA's Mars Polar Lander, which was similar in design to Phoenix, crashed when it neared the Martian surface on Dec. 3, 1999. The loss prompted NASA to turn to a more robust landing system using parachutes and airbags.
The robotic rovers Spirit and Opportunity used the system.
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