NASA managed to switch to the Hubble Telescope’s backup computer

NASA has taken an important step with Hubble, its space telescope down since June 13, 2021. The switch to the emergency on-board computer was carried out on July 15.

This is a very encouraging step: on July 16, 2021, NASA announced that she had managed to turn on the backup computer of the Hubble Space Telescope. The iconic observatory has been out of service since June 13, due to a problem affecting its on-board computer, the “payload computer”, the one that controls scientific instruments. In 31 years in space, the Hubble telescope had never encountered this kind of problem. Attempts to restart and reconfigure this on-board computer were unsuccessful.

In its press release, regularly updated since the start of the blackout, NASA writes that “ successfully back-up hardware on the Hubble Space Telescope, including powering up the backup on-board computer, July 15 “. In spacecraft, such as Hubble or satellites, there is generally redundancy, i.e. duplicate (or even triplicate) on-board components, in order to have a fallback solution, in the event of technical concern. The Hubble space telescope is carrying a back-up on-board computer: it is on this “plan B” that NASA was counting to resolve the current failure.

The space agency had just identified a lead on the origin of the concern encountered by Hubble on July 15. The on-board computer is located in a unit called “Science Instrument Command and Data Handling” (or SI C&DH). In this unit, there is also the power control unit (“Power Control Unit” in English, or PCU): it is this which would probably be in question.

Source : Flickr/CC/Nasa (p

Switch on two emergency elements

The recent maneuver carried out by NASA therefore involved lighting two elements, which are on the other side of the SI C&DH unit:

  • the emergency power control unit,
  • as well as the control unit (of its full name “Command Unit / Science Data Formatter”, or CU / SDF), back-up.

The power control unit ensures that every part of the on-board computer is supplied with constant power. The control unit is used to process and transmit data (scientific and technical) and instructions.

« Once these steps are completed, the emergency on-board computer on the same unit [ndlr : du côté « backup » de l’unité SI C&DH] has been turned on and loaded with flight software and returned to normal operating mode », Says NASA. Now the team responsible for the Hubble Telescope must monitor the hardware to make sure everything is working as expected. After this verification phase, the scientific instruments should become operational again. However, you must first perform procedures and ensure that the temperatures of the instruments are stable. They will then need to be calibrated before they can collect reliable scientific data again.

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