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Preparing for Mars rover landings

From As NASA’s two Mars rovers whisk through space, back here on Earth, there’s no rest for scientists and engineers as time till touchdown for each spacecraft clicks away.
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As Spirit and Opportunity, NASA’s two Mars rovers whisk through space, silently and speedily closing in on the red planet, back here on Earth, there’s no rest for scientists and engineers as time till touchdown for each spacecraft clicks away.

EXPERT TEAMS ARE in get-a-move-on-mode, sharpening their collective skills, final checking software, and confirming actions for safely landing and then driving the twin tele-robots across dusty Mars.

At the Jet Propulsion Laboratory (JPL) — rover builder and manager of the Mars Exploration Rover project for NASA — it’s already show time. And practice makes perfect as the curtain rises on opening day of the next era in Mars exploration.

SANDBOX TIME A series of ten Operational Readiness Tests (ORTs) are taking place at JPL prior to the rover landings. “We’ve got some incredibly complex test and training exercises planned,” said Steve Squyres of Cornell University, Ithaca, New York. Squyres is principal investigator for the package of science instruments carried on each rover.

“We have never yet done a full-up, Mars-time simulation of nominal surface operations with these rovers. The software, tools and processes can be tested in isolation. But the only way to convince yourself it works is to try it all together on Mars-time,” Squyres told .

Back-to-back shakeouts of software, hardware and procedures are on the to-do list. Rover teams are putting in hours of “sandbox time” — practicing their moves on Mars in a facility holding rover replicas that scoot about on martian-like dirt and rocks, and is bathed in sunlight that mimics the condition found on the red planet.

Next week, rover teams will spend five “sols” — a Martian day, or sol, lasts 24 hours, 39 minutes and 35 seconds — operating real machinery with real instruments in the Mars-like sandbox. “I expect a 100 scientists for that simulation. It’s going to be a circus,” Squyres said.

In October, a 10-day ORT will have teams not only running one rover, but also handling in parallel some seven days of landing and start-up operations of a second rover. “It’s the ORT that may kill us all,” Squyres added.

Each passing day, the intervening void between the rovers and Mars gets smaller.

ON-THE-JOB TRAINING Spirit arrives first at Mars. Wrapped in airbags, the rover is set to drop onto the planet on the evening of January 3, 2004, U.S. Eastern and Pacific times. Its target zone is the giant Gusev Crater and a spot to search for geological evidence about the history of water on Mars.

Three weeks later, and half way around the planet, Opportunity is to plop down at a site on Mars called Meridiani Planum. This second lander is slated to come to a full airbag stop on the evening of January 24, Eastern and Pacific times. Meridiani Planum appears loaded with hematite, a mineral that usually forms in wet environments.

The wheeled rovers are not built for speed. Rather, they carry tools of the trade, functioning as robotic geologists. Armed, quite literally, with a suite of instruments, the rovers can reach out and probe rock and soil for clues about whether past environments at their respective landing sites may have been hospitable to life.

“The operation of two individual rovers simultaneously moving about the surface of Mars is going to be something that is quite new,” said Dan McCleese, chief scientist for the Mars program at JPL. “The process will be two rovers, two teams, with several sets of people working on each team in order to cover it around the clock,” he said.

McCleese said getting the rovers off Earth and on their way to Mars is one thing. “The exciting thing now is finishing up the work we have to do before the missions on Mars start.”

No doubt, rover teams will encounter much in the way of on-the-job training.

“No matter how much training we do there will be surprises,” McCleese said. “We already known surprises are in store regarding what the Mars rovers will actually land on. We can practice all we like. But we don’t have the data in hand to tell us what kind of obstacles we’ll encounter. Will we land far away from something interesting…or right next to what’s interesting?”

FACE TO FACE INTERFACING The dealings between science and engineering teams that operate the rovers are far more intense than it is on any Mars orbiter mission.

“You’ve got to hone and tune your entire team. That involves a lot of engineering and science interfaces,” said Gentry Lee, chief engineer of JPL’s Planetary Flight Systems directorate. He is no stranger to Mars and running complex hardware on a world that’s harsh and unforgiving.

Lee is a Viking veteran — the notable Mars mission of the 1970s that involved two orbiters dispatching two landers down to the surface of the red planet. He recently led a review of remaining steps needed to be taken in getting the dual rovers safely down and running on Mars early next year.

“There is an unyielding date coming up. The job is now determining those things that are higher priority than others are. It’s a great team…and they will be ready,” Lee told .

Lee said the days ahead for training teams prior to the landings are critical. “We want the teams of people who are going to be working together during the actual events also working together during the tests … so we can build that team sense.”

In Viking two orbiters and two landers were flying, but integrated into one organization, Lee said.

It’s different with the Mars rover squad. “What they’ve done is taken the two rovers and basically bifurcated the whole team,” Lee said.

What remains to be shown in the testing between now and the landings is whether or not that strategy holds up, particularly if — more likely when — problems arise.

THE WHALE AWAITS JPL’s Matt Golombek is also no newcomer to Mars. He served as the Mars Pathfinder Project Scientist, and sharpened his rover skills thanks to the Sojourner robot that strolled across the red planet in 1997.

Among several hats he wears, Golombek is also the Mars Exploration Rover landing site scientist.

“Actually, most of us on the Mars Exploration Rovers feel like Jonah and the whale…and the whale is about to swallow us up,” Golombek said. “But that’s okay. Where else would you want to be? The most important job for me is to get those guys down to the right spots on the planet.”

All is on target for dropping into Gusev Crater and touching down at Meridiani Planum. Even with the rovers in-flight, the landing zone ellipses at each site are still being assessed and finessed, Golombek said.

For Meridiani, it’s finding the warmest areas where the rover can live longer despite the cold climes of Mars. Within Gusev, Golombek added, the key is staying away from rough terrain that could increase risk of mission failure.

“You don’t know exactly where you’re going to come down within an ellipse. You’re never going to be exactly where you target,” Golombek said.

During the final hours of approach to Mars, adjustments can be made to each rover’s on-target trajectory. Thanks to precise boosts off and away from Earth, both rovers carry loads of maneuvering fuel, Golombek said.

GREMLINS AND ELVES Squyres emphasized that the practice sessions throughout the remaining year are critical to mission success. “If you take our schedule and lay it out from now until landing ... it is wall to wall.”

Taking part in the tests, Squyres explained, are mean-spirited gremlins and helping hand elves.

“You cannot provide 100 percent fidelity during the ORTs. It is a rover, but not a flight rover. We are in a Mars-like facility, but it’s not on Mars. We’ve got people who are the elves that help you. They go in and fix things to make it seem more Mars-like to us Earthlings. The gremlins are the ones who go in and intentionally create problems for us to solve,” Squyres said.

Bottom line: Lessons learned ahead of time should equal fewer surprises on Mars.

Running a rover through one sol is price tagged at $4.5 million. So wasted time or making procedural errors that bring rover operations to a grinding halt not only mean loss of science data, but also money.

“We don’t want to make too many $4.5 million dollar mistakes. The point of our operational readiness tests is to make our mistakes now ... so when we get to Mars we’ll be very good at what we do,” Squyres noted.

Spirit and Opportunity are both looking good, although checkout of all instruments en route is still ahead. Overall, the health of the vehicles is excellent, Squyres said. “I’m anticipating it’s going to be pretty quiet. We haven’t had any significant anomalies onboard either vehicle yet. And I’m hoping it stays peaceful.”

Given the long haul to Mars, what are the odds for success?

“If the performance of the vehicles so far is any measure of the quality of these spacecraft ... then you’ve got to think our chances are pretty darn good,” Squyres concluded.

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