Hubble Status Report #5
On Monday, October 20, engineers at NASA’s Goddard Space Flight Center met to discuss their next steps toward resolving two anomalies which caused the B-side of the Science Instrument Control and Data Handling System (SI C&DH-B) and the Advanced Camera for Surveys (ACS) Solar Blind Channel (SBC) to return to a ‘safe hold’ status on October 16. Following that meeting, an Independent Review Team (IRT) chaired by the Director of the Wallops Flight Facility also met. The near-term focus of the HST Program’s efforts and the IRT’s efforts will be to assess the risks of activities needed to resume making observations with HST’s three functioning science instruments prior to Servicing Mission 4. The next meeting of the full IRT will occur on October 22.
Over the weekend, the Hubble team continued detailed reviews of all the data available when last week’s anomalies occurred. A suspect 8-volt power source within the SBC’s low voltage power supply (LVPS) reached its nominal output value just after failure of an internal check monitoring its health. Hubble engineers are evaluating alternative procedures and determining whether another attempt to restart the LVPS presents a risk to the instrument or to the planned SM4 repair of ACS’s other cameras. (SI C&DH-B reactivation must precede SBC turn-on.)
Intensive study of the SI C&DH-B shutdown also continues. Analyses done thus far suggest that an electrical event of unknown origin and characteristics caused 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). Both of these modules were activated on-orbit for the first time on October 15. Additional analyses and a risk assessment of SI C&DH-B reactivation have begun.
All other subsystems on Hubble are performing nominally, and astrometry observations with HST’s Fine Guidance Sensors continue.