Don’t you wish sometimes that your life had a “re-do button”? Something that automatically gives you a second chance? A second wind that picks you up and keeps you going?
Imagine: your car’s transmission gives out. Hey, no problem! You flip the “Backup Transmission” switch and you’re back on the road. Awesome, right?
Lucky for them, most spacecraft out there are built with backup systems such as that. If one component fails or gives you problems, you switch over to the backup component, and away you go. The space shuttle orbiter had five backup computers, and almost none of them were ever used. But, like your grandma used to say, “Better to have it and not need it than to need it and not have it.” Space exploration lives by that principle.
And since there is usually no way to fix a spacecraft once it’s been launched, backup systems are a must.
Case in point: the venerable Mars Odyssey spacecraft. It has been in orbit around the Red Planet for around 11 years. It made headlines earlier this year when one of its reaction wheels failed (and boy, do we know about reaction wheels here at OUR SPACE!). But Mars Odyssey gets better: it is actually twin spacecraft in a single shell!
There are duplicates for most of its instrumentation on its “B side.” And when engineers saw trouble in “A side” units, they decided to switch the whole spacecraft to the “B side” before any components actually failed.
So now we basically have a brand-new spacecraft out there, and apparently the 11-something years worth of shelving have had no negative effect at all — the switchover occurred smoothly, and Mars Odyssey is humming along again, doing its thing of surveying Mars and relaying data to and from the rovers on the surface all the way to Earth.
Needless to say the Mars Odyssey mission team is ecstatic, for not only do they have all brand-new instruments to work with — they also have all the old ones that still work and estimates are for at least a few more months of useful life. So, if they have trouble with any “B side” instrumentation, mission managers can switch back to the aging but still functional “A side” temporarily while they analyze the other problem.
It’s a win-win situation all around.
Of course, this fabulous life-extender didn’t come for free: any redundant or backup system on a spacecraft increases its weight and mass, making it more expensive to launch and less efficient to maneuver for course corrections. But it’s a cost increase that pays for itself the moment the backup system is actually used, because without it, failure is no longer an option, it’s a certainty.
Read up on Mars Odyssey 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