NASA continues to diagnose the problem of the Hubble payload computer. The computer went out of order on June 13 and the apparatus stopped collecting scientific data. The telescope itself and its scientific instruments remain in good condition and are in a safe mode.
The spacecraft has two payload computers, one of which serves as a backup, they are located on the block of scientific instruments and the command and information data processing system (SI C&DH).
Additional tests conducted on June 23 and 24 included rebooting a backup computer for the first time in space. Tests showed that numerous combinations of these hardware parts of both the primary and secondary payload computers showed the same error – the commands to write to memory or read from memory were not successful.
Since the problem is unlikely to occur in all the individual hardware elements, the team is now looking at other hardware as a possible culprit, including the Command Block / Scientific Data Format (CU / SDF), another module on SI C&DH. The CU formats and sends commands and data to specific addresses, including scientific instruments. SDF formats data from scientific instruments for transmission to the ground. The team is also examining the power regulator to find out the voltage level. If the voltage is out of tolerance, it can cause the observed problems.
Over the next week, the team will continue to evaluate the hardware on the SI C&DH block to determine if something else might be causing the problem. If the team determines that the probable cause is a CU / SDF module or a power regulator, it will recommend switching to a standby CU / SDF and a standby power regulator.