Mars Craft Succeeds in Soft Landing
Phoenix to Begin Search for Signs of Life Beyond Earth
Monday, May 26, 2008; Page A01
The spacecraft Phoenix landed safely on Mars yesterday, making a hazardous soft landing on the planet's far north with all its scientific systems apparently intact and ready to begin an intensive new search for life beyond Earth.
After counting down the last stage of the descent by hundreds and then tens of nerve-racking meters, officials at Mission Control in Pasadena, Calif., announced that "Phoenix has landed," setting off a joyous celebration by the mission team.
The touchdown, at about 8 p.m. Eastern time, was the first successful soft landing on the Red Planet -- using a parachute and thrusters rather than protective air bags -- since the twin Viking missions in 1976. In all, six of 11 similar attempts by the United States, Russia and England ended in failure, so the Phoenix team awaited with enormous apprehension the outcome of the spacecraft's approach and landing.
Phoenix plunged into the thin Martian atmosphere traveling at more than 12,000 mph. Over the next seven minutes, friction -- which raised the temperature on the heat shield to 2,600 degrees Fahrenheit -- slowed it enough to deploy the parachute.
About half a mile from the surface, and with only seconds remaining before touching down, 12 small rocket thrusters fired to slow the lander's descent speed to 5 mph. Before it landed, however, Phoenix had to orient itself toward the sun to ensure that its solar panels could pick up enough light to generate the power it will need on the surface.
Like the Viking landers, Phoenix is designed to look for organic material and other signs that life has existed on Mars, or could exist on the planet. Unlike the two rovers that have been exploring the Martian surface for nearly five years, Phoenix is built to stay in one place and use its robotic arm to dig into the soil and ice. The vehicle is equipped with several miniature chemistry labs to analyze the material it digs up.
The lander touched down further north on Mars than any previous lander. NASA scientists think the frozen water on or near the surface may tell them whether the minerals and organic compounds needed for life as we know it exist, or have ever existed, on the planet.
Throughout the descent and landing, NASA engineers at the Jet Propulsion Laboratory were receiving data on the spacecraft's progress 15 minutes after events occurred -- helpless to intervene if anything went wrong. Transmissions were sent from Phoenix to the orbiting Mars Odyssey spacecraft, then relayed back to Earth at the speed of light over the 171 million miles between the planets.
Phoenix, named for the mythological bird reborn from its ashes, was assembled largely from parts manufactured for other spacecraft. After two Mars mission failures in 1999, the space agency scrapped a lander mission planned for 2000 and recycled some of the hardware.
One of those failures was the last time NASA tried a soft landing on Mars. The Mars Polar Lander was angling for the south pole when it prematurely shut off its engine and crashed to the surface below. The other failure involved a spacecraft that was supposed to go into orbit around Mars; NASA lost contact with it during the approach, and its fate is unknown.