NASA believes it knows where the failure of the Hubble space telescope came from

After more than a month of blackout, NASA has a lead on the origin of the concern encountered by Hubble. The problem would lie with the unit which controls the power supply to the parts of the on-board computer.

The Hubble Space Telescope has now been out of service for over a month. The scientific operations of the observatory were suspended on June 13, 2021. NASA announced on July 14, in his press release regularly updated about the telescope failure, that a potential cause of the problem had been identified.

This is an unprecedented problem that Hubble has encountered in 31 years in space. The scientific instruments are not damaged, but the concern is with the Hubble on-board computer, which is responsible for controlling and coordinating the instruments. It is located in a unit called “Science Instrument Command and Data Handling” (or SI C&DH). For several days, NASA conducted tests, including attempts to restart and reconfigure the on-board computer, which failed to resolve the issue. However, ” the information gathered from these activities led the Hubble team to determine that the possible cause of the problem lies in the power control unit “Writes NASA (” Power Control Unit “in English, or PCU).

Hubble’s Power Control Unit (PCU). It was replaced in 2002. // Source: Wikimedia / Public Domain / Nasa (cropped photo)

What is the power control unit used for?

This power control unit is also housed in the SI C&DH. It ensures that every part of the on-board computer is supplied with constant power. ” The PCU contains a power modulator that supplies constant five-volt electricity to the on-board computer and its memory, details the space agency. A secondary protection circuit detects the voltage levels coming out of the power modulator. If the voltage drops below or exceeds the tolerated levels, this secondary circuit indicates to the on-board computer that it must cease operations.. »

Thus, two possibilities are considered by the space agency:

  • Either the voltage level of the power modulator is outside the levels considered tolerable, which has triggered this secondary protection circuit,
  • Either this secondary protection circuit has worn out over time and is currently blocked.

No command sent from the ground succeeded in resetting the power control unit. NASA is currently planning to switch to the back-up computer located in the SI C&DH unit, which contains a back-up power control unit. This changeover must take place this Thursday, July 15. If this works as expected, it will take several more days for the scientific activities of the Hubble Space Telescope to resume.

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Source: Numerama by

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