An artist's concept illustration depicts NASA's Phoenix Mars Lander, released to the media May 25, 2008. Source: NASA/JPL-Calech/University of Arizona News
May 26 -- NASA's Mars Phoenix Lander touched down safely today on the Red Planet, where the probe will sift through the icy soil for any signs that it once harbored life.
`We've passed the hardest part and we're breathing again,'' Mars Phoenix Project Manager Barry Goldstein said, according to NASA. The Red Planet's rocky terrain and equipment problems have led to the failure of more than half of all Mars missions, including a Phoenix predecessor destroyed in 1999.
Phoenix sent a signal confirming it landed safely in the northern polar region of Mars, the National Aeronautics and Space Administration said on its Web site. The message took 15 minutes to travel to Earth from Mars at the speed of light.
The probe is part of NASA's current theme in Mars exploration: follow the water. Ice is plentiful beneath the red soil and the space agency wants to know whether liquids also exist underground. ``Where there tends to be water on Earth, there tends to be life,'' Lynn Craig of NASA's Jet Propulsion Laboratory said in an interview. ``So it's potentially a place where life could have existed.'
After its landing, Phoenix relayed pictures from the planet showing the plain and horizon, a foot of the craft on the soil and its solar panels extended so that it will be able to generate power, according to NASA.
Landing Risk
The riskiest segment of the Phoenix's 420-million-mile (676-million-kilometer), 9-month journey was the end. The Phoenix had only seven minutes to slow in the thin Martian atmosphere from almost twice the speed of sound to the pace of an escalator. Parachutes and braking rockets accomplished the task, each step initiated by onboard computers.
`Landing is easy; doing it softly is the hard part,'' said Mark Lemmon, an atmospheric scientist at Texas A&M University and co-investigator on the NASA project.
The previous ``soft landing'' on a planet was three decades ago, with NASA's Viking probes. Recent crafts sent to Mars, such as NASA's wheeled rovers, weighed less and relied on air bags to cushion the final impact.
Now on the surface, the Phoenix must work quickly. Martian winter begins in three months. The sun will drop below the horizon, and a thick ice of water and carbon dioxide will coat the lander's solar panels, ending its life.
Digging Process
The golf cart-size probe will use an 8-foot robotic arm, as well as a drill, to penetrate several feet of soil at the landing spot, near Mars's northern polar ice cap.
The flexible arm will scoop dirt and ice into ovens about the size of a matchbox. They will heat samples to 1,800 degrees Fahrenheit (980 degrees Celsius).
The probe will then test the burned soil for organic chemicals and minerals crucial to life. Much of the information can be analyzed on the spot and radioed back to Earth.
NASA's Viking probes also examined Martian soil in the 1970s, when the primary concern was locating safe landing spots. Dirt samples at those sites lacked much water.
The Phoenix, built by Lockheed Martin Corp., will be NASA's third probe active on the planet, along with the wheeled rovers Spirit and Opportunity.
Like Phoenix, they were given three months to live after touchdown. To NASA's surprise, the vehicles are still working four years later.
