Power Supply Trouble on Hubble

One of the two major failures that occurred last week on board the Hubble Space Telescope was associated with a “low voltage” 8v power supply for the ACS (Advanced Camera for Surveys) Solar Blind Channel. The ACS’ own processor noted that the power supply had not reached nominal voltage during power-up health checks, so the ACS processor shut down the instrument. Yesterday, NASA engineers reported that the 8v supply actually did achieve nominal voltage shortly after the health check came back negative. Every embedded hardware engineer I know is familiar with this problem. Power-on reset gremlins frequent many designs.

The cause of the other failure, a reset of both the Control Unit/Science Data Formatter-B (CU/SDF-B) and the NASA Standard Spacecraft Computer-1 (NSSC-1) Central Processing Module-B (CPM-B), is still unknown.

NASA’s independent review team (IRT) is meeting today (October 22) to further discuss the downloaded data and its implications with respect to resuming use of the Hubble’s imaging science instruments.