NASA has managed to restart the Hubble Space Telescope, after aging technology suspended science operations for a month. It seems the iconic instrument’s career may not be coming to an end, as had been feared.
On June 13, Hubble’s payload computer crashed, which automatically suspended science operations and placed the telescope’s instruments into a safe mode. Investigations suggested that the issue was the result of a degraded computer memory module, and restarts failed to get it back up and running.
Switching to a backup module was the next step but, frustratingly, the command to initiate the backup didn’t work. Over the following few weeks NASA worked to diagnose the problem, and develop and test procedures to switch to the backup module.
Eventually, NASA scientists determined that the fault lay in a regulatory circuit that monitors voltage levels within the Power Control Unit (PCU). Either the voltage levels were too high or too low, or the regulator itself had degraded and become stuck in the inhibit state, cutting the power for safety’s sake.
On July 15, the science team successfully switched on the backup PCU, as well as a backup Command Unit/Science Data Formatter (CU/SDF), which sends and formats commands and data. Other components were also switched to alternate interfaces to allow them to connect to the backup side of the computer.
With those steps successful, NASA scientists were able to switch on the backup payload computer and load it with flight software. A few more tests and calibrations, and science operations were finally able to resume.
Astronomers, scientists and the public in general will be breathing a sigh of relief. Hubble has shown incredible scientific value since its launch in 1990, and it will work well in tandem with the long-awaited James Webb Space Telescope, which is due to launch later this year after the pandemic derailed launch plans.