Touchdown! Phoenix lands on Mars

Planetary scientists Sunday night unveiled the first close-up color images of the northern arctic circle on Mars. The images were taken by the Mars Phoenix Lander only a few hours after its flawless descent onto the Red Planet’s northern plains at 7:38 p.m. EDT, May 25.

The images show a flat valley, devoid of rocks. “I know it looks a little like a parking lot, but that’s a safe place to land, by gosh,” said Phoenix project scientist Peter Smith of the University of Arizona in Tucson. “That makes it exactly the place we want to be. Underneath this surface, I guarantee you there’s ice.”

The region, he added, is “surprisingly close to what we expected — that’s what surprised me the most.”

In about a week, the craft’s robotic arm is expected to begin scooping up samples of the dirt and find the ice, Smith told reporters at a briefing at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. The sample will be delivered into miniature ovens that will look for organic compounds and determine whether the region can now or ever did sustain some form of life.

One image shows a polygonal structure that may indicate that ice lies just beneath the surface. Similar polygons are found in Earth’s polar regions, where they typically form from a cycle of freezing and thawing. “That’s probably the cutest polygon I’ve ever seen,” Smith said at the briefing.

The lander landed almost perfectly upright and its final vertical descent velocity was about the same as that of someone taking a stroll in a park, scientists reported. The region around the craft showed little disturbance, a sign that the soil there could be especially hard. But Smith said that would not pose any problem.

“We have practiced in very hard soils,” such as those in Death Valley, which are nearly as hard as concrete, he noted. “We can dig through those kinds of soils; it’s the solid ice that we can’t dig through.”

The lander delivered the images within hours of its safe landing on Mars’ northern plains. Radio signals received at 7:53 p.m. EDT May 25 confirmed that the lander had survived a difficult seven-minute descent and touchdown 15 minutes earlier. The signals were relayed by the Mars Odyssey spacecraft, which was orbiting overhead.

After slowing down at the top of Mars’ atmosphere, Phoenix reached a temperature of 2,600 degrees Fahrenheit during its hypersonic flight. In a series of carefully choreographed maneuvers, the craft then deployed its parachute, jettisoned its heat shield, deployed its three landing legs and activated its radar. It jettisoned its parachute and fired its thrusters the last 18 seconds before landing.

“We’re almost dead on,” to where we want to be, says mission project manager Barry Goldstein of JPL. “I’m in shock. Not in my dreams” did the landing go so well, he added.

The craft reached its destination after journeying 675 million kilometers since its Aug. 4, 2007, launch from Earth.