I love this stuff: Mars Craft Succeeds in Soft LandingPhoenix to Begin Search for Signs of Life Beyond Earth
By Marc Kaufman
Washington Post Staff Writer
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.
"It could not have gone better, not in my dreams," said Barry Goldstein, NASA's project manager at the Jet Propulsion Laboratory in Pasadena.
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.
Peter Smith of the University of Arizona, lead investigator for the mission, said earlier that the entry would amount to "seven minutes of terror" for the scientists.
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.
The 900-pound, three-legged Phoenix lander, which cost $457 million, traveled a circuitous path of 423 million miles over almost 10 months to reach Mars. A rocket-and-parachute landing system -- like that of the Viking landers of 32 years ago -- was chosen because it allowed NASA to better pinpoint the landing location. The system is also a prototype of one that NASA hopes will one day land astronauts on Mars.
The later Mars Pathfinder and the two robot rovers, Opportunity and Spirit, which have been exploring the planet's equatorial region, landed using air bags to cushion the impact. Air bags are not practical for heavier craft such as the Phoenix because the weight of bigger bags reduces the amount of scientific equipment that can be carried.
The Phoenix was targeted at the north polar region because that is where some form of water (in the form of ice) is most likely to be present, and scientists believe that a form of water is necessary for life. They are convinced that surface water flowed on Mars billions of years ago, a conclusion reached by studying geologic features of the Martian landscape. Today, conditions on Mars do not allow for liquid water, in large part because the atmosphere is only 1 percent as dense as Earth's.
In 2002, however, the Mars Odyssey orbiter discovered that large amounts of water ice lay just beneath the surface in the permafrost that covers much of far northern Mars. Scientists say the region, which is notably flat and smooth, may have once been the bottom of a large ocean.
They are also intrigued that the surface shows polygonal patterns remarkably similar to some seen in Antarctica. Scientists speculate that they could be the result of cycles of freezing and thawing.
In addition to its sophisticated cameras, soil retrievers and mini-laboratories, Phoenix carried on its journey a mini-DVD created by the Planetary Society called "Visions of Mars." It holds a library of science fiction stories and art, as well as the names of more than 250,000 people.
The DVD, featuring the likes of Carl Sagan, Arthur C. Clarke and Ray Bradbury, is made of material designed to last for hundreds, if not thousands, of years. http://www.washingtonpost.com/wp-dyn/content/article/2008/05/25/AR2008052502289.html?hpid=topnews