When a human being injures him/herself or gets sick, it’s not uncommon for that person to be restricted to bed rest for recovery. Turns out, it’s much the same for powerful space telescopes that have found themselves faced with a technical malfunction; NASA has announced that its Kepler spacecraft is to be placed in a “wheel rest” mode for ten days to allow itself to deal with a potential problem regarding increased friction on one of its reaction wheels.
NASA made the announcement last week in a project update for the Kepler Mission, explaining that during one of the Kepler project team’s semi-weekly contacts with the spacecraft – now more than 45 million miles away from Earth – it was discovered that one of the three reaction wheels on the craft was apparently requiring an increased amount of torque to spin. The issue had occurred both before and after the scheduled quarterly spacecraft roll on January 11.
That was a problem, but mostly because it signified an even larger complication down the line; the necessity for extra torque meant that there was a possibility of increased wear on the craft’s reaction wheel, which could result in wheel failure down the line – something that isn’t easily repairable when the craft is that far out in space. In order to try and deal with this problem before it happens, the Kepler team decided to essentially pause the mission for a ten-day period in the hope that resting the wheels will allow for a natural redistribution of internal lubricant, which may fix any friction problem naturally.
The reason for such concern ahead of time is that, if the problematic wheel ends up failing, it would be the second wheel to do so on the mission to date, and would impact the mission substantially (A fourth wheel failed last July, stopping turning altogether).
Charlie Sobeck, the deputy project manager at NASA’s Ames Research Center, seems to be taking the rest period in his stride and downplaying the potential for disaster. In an email to New Scientist, he described the problem as a simple personality clash. “Each wheel has its own personality,” he explained, “and this particular wheel has been something of a free spirit. It’s had elevated torques throughout the mission. This one is typical to what we’ve seen in the past, and if we had four good wheels we probably wouldn’t have taken any action.”
When the Kepler returns to work after its ten day vacation – spent with its solar panels realigned to face the sun, to allow for maximum charge – it will take three days to get the craft ready for a continuation of its mission. If only the rest of us had such relaxed re-entries into work after some time off.