"We have done everything humanly possible to get ready for Mars Orbit Insertion," says David A. Spencer, Odyssey's mission manager.
Early next week the final commands will be uploaded to prepare the craft for the insertion maneuver. Then everyone waits for nine days. Finally, with exactly 6.5 hours to go, mission managers will have their final opportunity to make last-minute course corrections.
Then they wait some more.
The probe will fire its thrusters and begin a delicate dance with the Red Planet's gravity. Then Odyssey will disappear behind Mars, unable to communicate with Earth. If it emerges as planned 20 minutes later, it will send a signal that all is well. A cheer will go up at NASA's Jet Propulsion Laboratory, celebrating its first successful mission to Mars in three tries.
"If all goes well, we just sit back and watch it happen," Spencer said in a telephone interview recently. "The nail biting time is going to be during that 20 minutes once we see the burn and then go behind Mars."
The Odyssey mission is the first attempt to reach Mars since 1999, when two JPL-run missions ended in disaster. Mars Climate Orbiter failed to go into orbit in 1999 because of a human mixup between metric and English units. A few months later, the Mars Polar Lander did not reach the Red Planet's surface, possibly because it falsely thought it was on the ground and shut down its engines too soon.
Meanwhile, Odyssey has already experienced its share of glitches, though none threaten the overall mission.
Concern over science instrument
The problem of greatest concern is a science instrument that failed to respond in a routine data transfer session back in August. The Mars Radiation Environment Experiment, called MARIE, would measure potentially harmful radiation near Mars, a critical unknown that will determine how spacecraft, habitats and spacesuits are built for any future human Mars exploration.
A series of commands were sent over two days when the problem arose, but it was not solved. Mission managers then decided to focus on getting Odyssey to Mars and into a stable orbit before making any more long-distance fix-it attempts. So MARIE was put into hibernation.
In the meantime, engineers who manage the MARIE instrument at NASAs Johnson Space Center are working with the rest of the Odyssey team to figure out what went wrong.
"We're pretty optimistic" it will function, said Frank Cucinotta, a member of the MARIE team who is an expert on the effects of radiation on astronauts.
Cucinotta and his colleagues will wait until January to make their next attempt to revive MARIE. They will likely send new commands and possibly new software, Cucinotta told SPACE.com. They have no firm idea yet of what went wrong.
"It would be pure speculation to say," he said.
But there are some leads to work with. MARIE is similar to instruments aboard the International Space Station (ISS). "And we do know sometimes those instruments have gotten locked up for long periods of time," Cucinotta said.
The ISS instruments have been revived, giving Cucinotta and his colleagues some hope. Techniques that have worked with ISS instruments may be employed in trying to revive MARIE.
Star-tracking camera
Odyssey's other nagging problem seems to present no serious problems for the mission.
The probe's star-tracking camera has proved troublesome over the past several weeks, however. The camera is used to maintain the probe's orientation in space. When the spacecraft is in certain orientations, the camera has been flooded by sunlight, rendering it ineffective.
A shade inside the camera is supposed to prevent this. Engineers determined that the problem was, in part, caused by light reflected from the door of another instrument. That door has been closed to alleviate the problem for now.
The star tracker won't be used during the insertion maneuver, but it will be required afterward. Odyssey's mission calls for at least three years of circling Mars. It will not land on the planet.
Spencer said thorough tests show the star tracker will perform adequately when needed.
Insertion: Lots can go wrong
Odyssey's insertion into orbit is slated for 10:30 p.m. ET on Oct. 23. Hopes run high that this crucial part of the mission will go well.
"In our minds, it's not ok to fail," said Odyssey project manager Matt Landano. "We must succeed."
But like everyone involved in the mission, Landano knows there are no guarantees.
"In a complex system like a spacecraft, about a million little things have to happen right. The real complex stuff everyone is watching," Landano said. "It's the things that you've done many times that you think you know how to do. Somehow, that's the thing that bites you."
So what are engineers doing? They are questioning things. Lots of things.
"There's a certain level of healthy paranoia I think it's important to keep," explains Charles Whetsel, chief engineer of the Mars Exploration Program at JPL. "The people you really want on your team are the ones who are really bothered by things like 'Why does that telemetry point always read a little different from those other ones? Is that trying to tell me something?'"
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