After more than a month in safe mode, the Hubble Space Telescope is finally on the mend. The observatory had ceased operation on June 13 due to a problem with its payload computer.
Hubble had ceased operations on Sunday, June 13, 2021 due to an issue with its payload computer, which resides in the Science Instrument Command and Data Handling (SI C&DH) . However, it is he who controls the scientific instruments of Hubble. When this computer shut down, the instruments were automatically placed in safe mode.
Subsequent attempts to restart and reconfigure the computer and its backup computer were unfortunately unsuccessful. However, information gathered from these maintenance activities has allowed engineers to determine that the possible cause of the problem lies with the Power Control Unit (PCU) which supplies voltage to the computer hardware.
Concretely, the PCU offers a power regulator that supplies constant five-volt electricity to the payload computer and its memory. A secondary protection circuit is then responsible for detecting abnormal voltage levels. If the voltage drops below or exceeds allowable levels, this secondary circuit tells the payload computer to cease operations.
Based on the Hubble team's analysis, either the regulator voltage level here was outside of acceptable levels (thus triggering the secondary protection circuit), or the secondary protection circuit had deteriorated over time and finally remained stuck in this configuration.
Since the PCU reset could not be done from the ground, the team had to switch to the backup PCU. These operations began on July 15. The next day, NASA had managed to activate the backup computer system. All the scientific instruments of the telescope were finally reactivated on July 17 . The latter will resume scientific observations after completing the calibrations.
“I am proud of the Hubble team. Current and former members of this team stepped in to provide support and expertise “said NASA Administrator Bill Nelson, the new NASA Administrator. "Thanks to their dedication and thoughtful work, Hubble will continue to build on its 31-year legacy, expanding our horizons with its vision of the universe “.
Astronomers remain optimistic that Hubble, which has contributed to some of the most important discoveries in our cosmos, including accelerating the expansion of the universe, can continue to operate until 2030 .
