NASA identifies computer problem on Hubble, says fix will take a few days

Washington DC (UPI) Jul 15, 2021 - Engineers at NASA have identified the potential cause of a payload computer problem that has sidelined the Hubble Space Telescope for more than a month.

The agency said Thursday it would start a process to switch to a backup system, and that the telescope could be back to normal operations within a few days.

The payload computer, part of Hubble's Science Instrument Command and Data Handling unit, or SI C&DH unit, controls the telescope's many scientific instruments. When it froze, Hubble's instruments automatically halted operations and went into "safe mode."

After weeks of investigation, engineers at NASA have traced the problem to Hubble's Power Control Unit, or PCU, which is also located in the SI C&DH unit.

The PCU features a power regulator that supplies the payload computer and its memory with a constant supply of power. The five-volt flow of electricity is monitored by a secondary protection circuit. If power supply levels drop, the protection circuit tells the payload computer to halt operations.

NASA engineers suspect the flow of electricity from the PCU has either dropped below acceptable levels or the protection circuit has malfunctioned.

Because ground control signals have failed to reset the PCU, engineers have been given the green light to activate the backup side of the SI C&DH unit, which contains a backup PCU.

"The switch will begin Thursday, July 15, and, if successful, it will take several days to completely return the observatory to normal science operations," according to news release from NASA.

Now over the age of 30, Hubble has experienced dozens of technological hiccups over the years, but time and again, engineers have managed to find a fix.

Engineers performed a similar SI C&DH unit switch after a component failure in 2008. The entire SI C&DH unit was replaced during a servicing mission in 2009, allowing Hubble to resume normal operations.