By Blaine P. Friedlander Jr.
After a six-month journey through space, Spirit, the first of the twin Mars rovers, is scheduled to bounce down on the red planet's Gusev Crater Jan. 3, 2004, at about 11:35 p.m. EST. But for the Cornell team that designed the rovers' Athena instrument package and who will be monitoring the tools during the mission, Spirit's run will be just beginning.
The second rover, Opportunity, is scheduled to land on Mars Jan. 25 at 12:05 a.m. EST.
"Mars is getting pretty big in the windshield now," said Steven Squyres, Cornell professor of astronomy and the lead scientific investigator on the rover missions, at a media briefing at NASA headquarters in Washington, D.C., Dec. 2. He reminded reporters that while a good landing will be important, for the scientists, research is the thing. "This is a marathon," he said.
Although the rovers' primary mission is to search for evidence of water on Mars, Squyres cautioned the media that important findings are unlikely to occur immediately after landing. "The best stuff could come in February, March, April," he said.
Rover Spirit, he said, will plod the Martian landscape carefully. "It doesn't zip. It is more like a Galapagos turtle."
During the press briefing, Squyres revealed that during in-flight testing of the Athena instruments aboard Spirit in August, the Mössbauer spectrometer's drive system appeared to be jammed. Scientists and technicians from Germany and from the mission manager, the Jet Propulsion Laboratory (JPL) in Pasadena, Calif., worked slowly and methodically to solve the problem. Squyres reported that there was a minor obstruction in the drive system, probably a bent wire.
The Mössbauer spectrometer will analyze the composition and abundance of iron-bearing minerals to gather information about early Martian environmental conditions. The instrument was provided by Germany.
"You try to design an instrument with lots of margin," said Squyres in a recent online diary entry on his mission team's Athena Web site, http://www.athena.cornell.edu. "In other words, you try to make it better than it really needs to be. That way, if something goes wrong, it might still work okay after you make an adjustment. We did [this] on our Mössbauer, and it paid off big time," he said.
The scientists adjusted the instrument's vibration velocity and the frequency, giving it less total motion. "While we never expected to operate the instrument with a total motion that small, we built it with enough margin that the spectrometer still will work properly on Mars," Squyres said.
In late November, Squyres and his science team completed the last operations-readiness test at JPL. The team simulated five Martian days of driving a practice rover, using the vehicle's version of a geologist's rock hammer, the rock abrasion tool, or RAT. "We use it to remove the outer layers of a rock so that we can see what lies underneath," said Squyres in his online diary.
The team spotted a rock to study, nicknaming it Fromage, which means "cheese" in French. "Bait for the RAT, get it?" joked Squyres. "We drove the rover to Fromage, stuck out the arm, and used the RAT to grind a beautiful circular hole in it. Then we stuck [the Athena] instruments into the hole and got fantastic data. It was by far our coolest [test] yet. It was nice to finish up on such a high note."
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