Mission to Red Planet needs more green to stay on track

Jim Erickson, Rocky Mountain News

Wednesday, January 17, 2007

NASA's $386 million, Colorado- built Phoenix mission to Mars is over budget and needs an extra $10 million to $35 million to stay on track for a planned August launch, the lead scientist said Tuesday.

University of Arizona planetary scientist Peter Smith said he will plead his case to NASA officials in Washington, D.C., on Jan. 26.

"We have budget problems," Smith said. If NASA doesn't provide the funds, the Lockheed Martin- built mission could miss its August launch window and face cancellation, he said.

"We think our mission is an important one, and a few percent overrun shouldn't be something that prevents us from doing it," he said. "But of course it's up to NASA to make that ruling."

Doug McCuistion, director of NASA's Mars exploration program, could not be reached for comment Tuesday. But he told Space News on Jan. 10 that the Phoenix overruns are large enough to harm other projects in NASA's Mars program.

"The Phoenix overrun is going to have some effect on us," he said.

Named for the mythical bird reborn from its own ashes, the three- legged Phoenix lander will carry new versions of science instruments destroyed when another Lockheed Martin-built craft, Mars Polar Lander, crashed while landing Dec. 3, 1999.

The new devices will ride on a Lockheed Martin spacecraft that was mothballed when NASA canceled its 2001 Mars Lander mission after Polar Lander's demise.

Several problems surfaced as the 2001 spacecraft and its instruments were completed, upgraded and tested for the Phoenix mission. Overcoming those problems led to cost overruns, Smith said.

When it lands on Mars, Phoenix will use a radar altimeter that tells the onboard flight computer how high the probe is and how fast it is moving. The computer then decides when to release the parachute and fire the braking thrusters that allow Phoenix to settle onto the surface.

Engineers tested the radar last year by dropping it from a helicopter on a long cable to simulate the descent to Mars, said Edward Sedivy, the Phoenix flight system program manager at Lockheed Martin.

During the tests, readings from the radar altimeter were compared to positions derived from the Global Positioning System satellite network. The altimeter and GPS reading didn't jibe, forcing Lockheed Martin engineers to "fine tune" the radar unit, Sedivy said.

"There were some performance issues," he said Tuesday. "There were some things that we found that needed to be fixed."

And the fixes boosted costs.

So did the protracted search for a safe landing site.

Phoenix will land on, and dig into, the northern polar plains, where vast stores of ice have been detected just below the surface.

Mission planners thought they'd found an acceptable landing zone, about the size of Arizona, known as Region B. But when NASA's Mars Reconnaissance Orbiter sent back the first razor-sharp pictures from its Boulder-built HiRISE camera last fall, the images showed car-size boulders scattered across Region B.

The scientists and engineers were forced to reconsider other sites and will meet next week to pick a new landing spot.

"The spacecraft's performing as it should, we're finding landing sites now and it's all looking good," Smith said.

"I don't know of anything that'll cause us to slip the launch at this moment - unless they don't give us the money, of course."

NASA's Phoenix Mars Lander

Cost: $386 million

Built: Lockheed Martin Space Systems, Jefferson County

Scheduled launch: August 2007

Mission: Explore the ice-rich plains near north polar cap

Tools and science instruments include a 7-foot, jointed robotic arm to dig up to 20 inches beneath the surface, scooping frozen soil into a set of miniature ovens that will measure water content and look for minerals that may have formed during a wetter, warmer past climate.

ericksonj@RockyMountainNews.com or 303-954-5129