Just about any organization or program has its superstars — the ones who get all the publicity and general hype. When you say “NASA” to anyone, people immediately think of astronauts and not about the folks who brood over what liner material to use for a food container for them.
So when you hear “Mars Exploration,” you might think of the Mars rovers, specifically Spirit and Opportunity, the latter of which is still truckin’ along after all these years. Spirit has gone the way of the Dodo, but who doesn’t remember its valiant struggle to get out of the sand trap where it got stuck? NASA just released an eye-popping panoramic view of Opportunity’s surroundings — an image stitched together electronically from 817 individual pictures. Check it out at http://photojournal.jpl.nasa.gov/catalog/PIA15689
We wouldn’t have any of these pictures, or know much about what those rovers were doing on Mars without the Mars Odyssey spacecraft. Talk about longevity! Mars Odyssey has been hard at work for more than 10 years now, orbiting the Red Planet and taking high-resolution pictures and sending them back to Earth. Mars Odyssey was instrumental in finding the perfect landing site for the Phoenix lander because its cameras are good enough to spot rough terrain, and based on its observations, scientists and engineers were able to pick a great spot. But Mars Odyssey also serves as a communications relay station for the rovers.
Granted, the rovers can send signals directly to Earth, but that requires a lot of power — electricity that mission managers would much rather use to let the rovers do their jobs and do the science and research they’re supposed to do! So to save power they send data packages to an orbiting Mars spacecraft, like Mars Odyssey. Twice a day the orbiter passes the rovers right overhead, and there’s a 10-minute window where the rovers can actually communicate with the orbiter. You can send a whole lot of data in just ten minutes!
Mars Odyssey collects these data bundles and passes them on to Earth every two days or so where they’re received by the giant dish antennas of the Deep Space Network (DSN) in Goldstone, Calif., or Madrid, Spain, or Canberra, Australia. That is one heck of a long distance call! Timing is everything, of course, because the DSN is used by many other missions for data uploads and downloads, so it makes a whole lot more sense to let the orbiting spacecraft do the job, rather than trying to aim for Earth while you’re already busy drilling a hole somewhere.
And, in fact, that good old work horse Mars Odyssey made the news recently — because it stopped working. And isn’t that always the tragedy of the unsung hero? Nobody talks about you when you’re doing a great job; it’s when you stop that people take notice. When was the last time you cheered because you could flush your toilet?!
Mars Odyssey, like most surface-observing satellites, uses so-called reaction wheels to orient itself in space, so its cameras point at the area someone wants a picture of. Reaction Wheels are rather heavy rotating structures that, when set in motion, actually move the whole spacecraft. With the lack of friction in outer space, the old principle of “every action having an equal and opposite reaction” works just like a charm. Reaction wheels can be spun up electrically and thus don’t use up any fuel, the way the reaction control system of the Space Shuttle did. Anyway, one of those reaction wheels got stuck for a while and put the orbiter into “safe mode” where all but the most critical functions cease until engineers can figure out what the problem is, fix it and then start it up again. It’s a little bit like anesthesia and subsequent surgery: you wake up and your broken bone is fixed.
Luckily, in space exploration everybody believes in backups; any component that can fail gets a replacement, especially moving parts and elements that are critical to a mission’s success. And even though the stuck wheel did spin up again, the engineers deemed it unreliable and switched to the backup wheel.
And, bada-bing!, Mars Odyssey was back in action! Needless to say, it was also out of the headlines once again.
You just can’t win.
So the next time you hear about the brave adventures of a Mars rover — be it the intrepid Opportunity or the soon-to-arrive Curiosity rover, take a moment to appreciate those helpers in the sky that make it possible for us to share the excitement of landing on Mars.
Want to know more about Mars Odyssey now? Check out its webpage at http://mars.jpl.nasa.gov/odyssey/
Beate Czogalla is the professor of theater design in the Department of Theatre and Dance at Georgia College & State University. She has had a lifelong interest in space exploration and has been a solar system ambassador for the Jet Propulsion Laboratory/NASA for many years. She can be reached at firstname.lastname@example.org.