NASA’s Kepler space mission may be coming to an unexpected end. The space agency announced on Wednesday that the spacecraft, designed to seek out possible earth-like extraterrestrial bodies, has suffered a malfunction that may make it impossible to carry on with its search.
The problem appears to be a failure of a gyroscope, also called a reaction wheel. The spacecraft is now oriented with its solar panels facing the Sun as it slowly spins with communications being regularly interrupted as its antenna turns away from Earth. NASA has attempted to regain normal control, but with little success.
Kepler has been having attitude control problems recently and is in what is called “Thruster-Controlled Safe Mode” where control is shifted from the wheels to the spacecraft’s thrusters. NASA has been attempting to get all of the craft’s reaction wheels running properly, but number four wheel remains at full torque with the spin rate dropped to zero. This indicates that there has very probably been a structural failure of the wheel bearing.
Currently, mission control is making preparations to move Kepler into a Point Rest State during which the craft will be loaded with new software for loosely pointing in a way that allows its attitude to be controlled with minimum thruster use, yet maintaining constant communications on the X-band radio link. This will allow Kepler to conserve fuel for a period of years, but if the wheel cannot be brought back into operation, Kepler’s planet hunting mission will be at an end.
Launched in 2009, the Kepler spacecraft is tasked with finding planets orbiting other stars, with a particular focus on potentially habitable Earth-like planets. So far, it has detected 2,740 candidates and 122 planets have been confirmed. Without the ability to maintain exact attitude control in pointing its telescope, it will be unable to continue its photometric survey which, to put it mildly, would be a terrible shame.