The Phoenix Mars Mission has survived the fiery atmosphere of the Red Planet and transmitted a signal back to Earth, the first indication the spacecraft may have made a successful landing.
Scientists who have been nervously awaiting the end of the 10-month journey erupted in cheers and applause as the signal of a safe landing came in around 5 p.m.
"We are on the surface of Mars," said Chris Shinohara, science operations center manager at the University of Arizona, where the mission is headquartered. Several hundred scientists, their family and friends gathered at the operations center to hear a live feed from NASA as the craft touched down.
The spacecraft's critical solar panels also deployed. Without solar power, Phoenix cannot recharge its batteries and would have had only about 32 hours of operating power.
The $420 million mission is the first to land in the northern polar region of Mars, where orbiting cameras have detected evidence of subsurface ice. The craft is expected to deploy a digging arm that will scoop up soil and water ice, which will be analyzed to determine whether the planet may have been hospitable to microbial life.
"It's amazing when you think that we just landed on another planet," said Charles Elachi, director of NASA's Jet Propulsion Laboratory in California.
Loaded with 130 pounds of scientific equipment, the spacecraft has a nearly 8-foot robotic arm capable of scraping through soil into ice. The arm is designed to scoop up samples and transfer them to an on-board chemistry lab for analysis.
Phoenix covered 422 million miles on its journey to Mars. On Sunday afternoon around 4:45 p.m., the spacecraft dived into the planet's atmosphere at 12,600 mph and relied on a parachute and thrusters to slow itself to 5 mph. Three shock-absorber legs on the craft's bottom helped cushion the landing.
NASA officials were nervous about the landing, and for good reason. More than half of the 13 international attempts to land on Mars have been unsuccessful. NASA's last try at a powered landing in 1999 ended with the Mars Polar Lander entering the atmosphere and never being heard from again. After that failure, NASA identified and fixed more than two dozen potential problems that could have plagued the Phoenix landing.
Diana Blaney, a scientist with NASA's Jet Propulsion Laboratory, clasped her hands together before landing and tried to keep from biting her nails. She spent the day before landing going to a spa and getting a massage in an attempt to keep her nerves at bay.
"It's kind of out of my control," she said as she waited in Tucson, Ariz., for word that Phoenix had landed.
Blaney has seen great success and disappointment. She is a deputy project manager for the Mars rovers, which still operate on the surface more than four years after landing. She also was part of the Mars Polar Lander in 1999, which failed shortly after entering the Martian atmosphere.
She clapped and smiled when the touchdown signal came back from NASA.
"It's a huge relief," she said.
Then she prepared to work. She planned to spend Sunday evening analyzing the first pictures that come in from Phoenix. The images will give scientists clues about where to dig into the soil and ice.
Lead scientist Peter Smith expects Phoenix to take thousands of photos. One camera on the robotic arm is designed for close-up pictures while another is geared for panoramic views.
Scientists also can track the weather thanks to a $37 million meteorological station from the Canadian Space Agency. They can monitor temperatures, gauge wind speed and measure cloud cover.
The mission is expected to last three months, although it's possible Phoenix could function into mid-November or even December or January. Eventually, the sinking winter sun will deprive Phoenix of enough light to recharge its batteries.
Scientists said there's a slight possibility that Phoenix could come back to life after winter ends, but that's unlikely. The thick ice expected to envelope the spacecraft may damage its solar panels.
Phoenix joins two other ground missions already on Mars. NASA operates two, golf cart-size rovers near the equator that crawl at turtle speed. Both show signs of wear, even though they continue to take pictures and make discoveries. Dust coats their solar panels, and one of the rovers drags a broken wheel.
In addition to the land missions, NASA has two orbiters equipped with cameras and is a partner in a third orbiter operated by the European Space Agency.
The next NASA Mars mission, a rover project called Mars Science Laboratory, is planned for 2009. If Phoenix failed, it may have been difficult for NASA to justify any more Mars missions, Smith said.
Eventually, NASA would like to send a spacecraft to Mars and that could return to Earth with a soil sample.
(Contributing: Florida Today)