Hardware failure and disaster recovery are two terms that are closely associated with running a small business, and nothing more. However, this represents a giant misconception; one in which NASA can readily vouch for. Recently, NASA’s Kepler space telescope, which was responsible for identifying and classifying unknown planets, underwent major hardware failure.
Upon further review, the engineers realized that a single reaction wheel was not moving, and was subsequently to blame. The purpose of the reaction wheels is simple- they keep the telescope properly aligned with the target stars that they are viewing. Without these devices, the photons from the star would constantly bombard the telescope, and although they are individually of negligible mass, their combined effects would redirect the telescope slightly off course.
One would think that such an expensive project would make use of numerous fail-safes. One such preventative measure was the use of four reaction wheels, even when only three were necessary to maintain telescope stabilization. Unfortunately, one of the wheels became damaged in July of 2012 due to an insurmountable friction build-up. As a result of the July incident, the Kepler space telescope was heavily monitored over the past year by concerned scientists. William Borucki, Kepler’s principal investigator, explained to Wired in October, “The thought of it keeps me up at night.”
Due to the vast distance between the Earth and the damaged telescope, approximately 400 miles, it is apparent that any disaster recovery plan must be conducted remotely. So what are the recovery options?
At this point in time, there does not seem to be a quick fix. That being said, NASA has spent tremendous effort towards stabilizing the spacecraft to ensure that it is out of immediate danger. By successfully transitioning the telescope to Point Rest State (PRS) mode, any remaining fuel will be conserved, extending the amount of time to devise and execute a rescue plan. When in PRS mode, the spacecraft’s thrusters gently push the telescope towards the sun, and it is subsequently pushed back by the force of incoming photons. The entire motion resembles that of a pendulum and it is highly energy efficient.
In its current state, the telescope provides ongoing telemetry communication to the engineers. According to NASA, this allows them to both monitor and command the device. Using the information sent by telemetry, a detailed analysis by the anomaly response team (ART) is in effect. This team is comprised of major players from NASA Ames, the Jet Propulsion Laboratory, Ball Aerospace and the wheel manufacturer, UTC. Despite the progress being made, it will probably take several months before any formidable plan is constructed.
The big question is what the future holds for the telescope, especially if one of the reaction wheels cannot be fixed. For the past three and a half years, the Kepler spacecraft was in search of a possible replacement for the Earth. Paul Hertz, the astrophysics director at NASA, said, “Before we flew Kepler, we didn’t know that Earth-sized planets in habitable zones were common throughout our galaxy. We didn’t know that virtually every star in the sky had planets around them. Now we know that.”
Without three working reaction wheels, the accuracy required for planetary searches would be absent. The telescope would have to be put to other uses, possibly for the detection of nearby asteroids. Luckily, the Kepler telescope has already collected enough research for a couple more years of analysis. Borucki added, “We have excellent data for an additional two years. So I think the most interesting, exciting discoveries are coming in the next two years.”