Old and New Blend in NASA’s Next Mars Lander

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  Space News Business

Old and New Blend in NASA’s Next Mars Lander

By LEONARD DAVID
Space News Staff Writer
posted: 12 December 2006
02:53 pm ET




DENVER, Colo. — NASA’s next mission to the red planet — the Phoenix Mars Lander — is a true wedding of technology with planetary exploration: Something old, something new, something borrowed and something blue.

Named after the resilient mythological bird, Phoenix is based upon a lander that was meant to fly in 2001, but was administratively mothballed by NASA. It also is outfitted with instruments that are improved variations of gear carried on board the ill-fated Mars Polar Lander. That vehicle went astray during its descent to the Martian surface nearly seven years ago and was never heard from again, giving NASA managers blues for a red planet mission lost.

Here at Lockheed Martin Space Systems — the primary industrial partner for the mission — Phoenix is receiving an extensive, step-by-step shakeout in preparation for its launch in August 2007 aboard a United Launch Alliance Delta 2 rocket.

The spacecraft team is determined to get the unique lander safely down in May 2008 to carry out a suite of scientific chores at the icy soils near the north polar permanent ice cap of Mars.

Phoenix is scheduled to be the first lander ever to furrow into the martian polar surface. Using a lengthy and beefy robotic arm, it will hunt for subsurface water ice, and and a look for cozy nooks that might support life.

The $386 million Phoenix Mission is the first mission in NASA’s “Scout” program, said Edward Sedivy, Lockheed Martin program manager for the Phoenix Flight System. Mars Scouts are competitively proposed missions intended to supplement — at relatively low cost — the core missions of NASA’s Mars Exploration Program.

“When we started Phoenix, I don’t think anybody fully appreciated how much effort was required to really penetrate the designs that we inherited in 2001 and we’re bringing forward in Phoenix,” Sedivy said. “Adapting a set of designs that were put in place for the 2001 launch opportunity to the 2007 launch opportunity for Phoenix has been a real challenge.”

All is on track for Phoenix to be shipped in mid-May to Florida for launch processing.

At Mars, Phoenix will not land using airbags to cushion its landing as some previous missions have. Rather, it is designed to ease down onto the surface using sets of onboard thrusters.

“We have not done a controlled descent soft lander that succeeded since the Viking days in 1976,” Sedivy said. The last try at doing so was the botched Mars Polar Lander (MPL), also built by Lockheed Martin and lost on landing in early December 1999.

An investigation into that mishap at Mars reported in March 2000 that the most probable cause of the failure was the generation of spurious signals when the MPL legs were deployed during descent. Those spurious signals gave a false indication that the spacecraft had landed, resulting in a premature shutdown of the engines and the destruction of the lander when it tumbled onto Mars.

The same day that the MPL failure report was issued, NASA also announced the cancellation of the planned, but MPL-like, Mars 2001 lander.

When the termination was announced, the 2001 lander hardware was placed in full planetary protection protocol, said Matthew Cox, Lockheed Martin Space Systems manager for assembly, test and launch operations for Phoenix. “We treated it like it was going to Mars ever since the day that we had to stop work on it in 2000,” he said.

Resurrecting the stored lander for Phoenix meant a reversal of normal engineering practice, Cox said. “We actually had to start with a disassembly process,” noting that most programs build up a spacecraft piece by piece, not tear it down to the bare essentials.

The 12 descent rocket engines on Phoenix must perform over the last 35 seconds, right after parachute release, allowing the craft to slow itself down for a soft landing.

Cox said a lengthy test program has bolstered confidence that the motors for controlled descent of Phoenix can function as billed.

Still to be decided is the exact landing spot. “Finding a benign landing site that is relatively free of rock hazards would be a beautiful thing,” Sedivy said.

But early camera sweeps by NASA’s Mars Reconnaissance Orbiter of possible Phoenix landing zones have produced some nail-biting within the community of mission engineers and scientists.

“So far many of the images have small patches of boulder fields with boulders large enough and dense enough to be very worrisome,” said Peter Smith of the University of Arizona’s Lunar and Planetary Laboratory in Tucson and a principal investigator and project leader of the Phoenix mission. “We are currently searching for safe landing sites and have no reason to believe that we won’t find them.”

Sedivy said that portions of the baseline landing site for Phoenix are clearly rockier than anybody was anticipating. But he concluded: “The good news is that there is a lot of acreage that’s scientifically acceptable for the Phoenix objectives. So that’s a good thing.”