On July 16, after 35 days of diligent effort, NASA scientists successfully turned on the Hubble Space Telescope’s backup payload computer. Scientists also managed to switch to backup devices and started the process of restoring all gadgets from safe mode. The Hubble payload computer, which coordinates and controls the operations of the scientific instruments aboard the space telescope, stopped working on June 13.
Here’s how the NASA operations team did it:
June 13: Hubble’s payload computer shuts down. A persistence signal is not sent to the main computer. The main computer puts the device in safe mode to prevent damage.
June 14: An attempt to restart the computer failed. Preliminary data shows that memory modules could be responsible. Planned tests.
June 16: Preparations begin for the spare memory unit test. Scientists are running tests to determine if the offending memory module is the culprit.
June 17: The commands to run the backup memory module have not been completed. Attempts to bring both modules (current and backup) online failed. Scientists are unable to obtain more diagnostic data on the units. More tests are planned.
June 22: Test results indicated a defect in some hardware other than the memory modules. The investigation is ongoing.
23, 24 June: Computer backup runs, but memory error is not corrected. The team experiments with several combinations, including two payload computers – the primary computer and the backup computer. Scientists suspect that the problem was with the data science trainer/control unit (CU/SDF) or the power regulator.
Jun 30: Fixed issue – it was either the Scientific Data Control Unit/Trainer (CU/SDF) or the Power Regulator. The job of the CU/SDF is to send and coordinate commands and data. The power regulator in the power control unit provides a constant flow of five volts. Begin preparations to switch to backup devices.
July 14: Problem identified: either the voltage level was outside acceptable levels, or the secondary circuit, which checks voltage levels and requests a stop if it does not reach acceptable levels, is blocked in a damped state due to degradation. A switch to the emergency power control unit is required.
July 16: Successful transition to the Emergency Power Control Unit. Turn on the payload computer. Scientists are watching whether everything is working properly. The tool recovery process starts from safe mode.
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