Washington, D.C. – NASA said it has encountered problems with the Hubble space telescope following the transition from a malfunctioning control unit to a redundant device earlier this week. The operation of Hubble has been suspended when another “anomaly” was detected.

Prior to the new problems, NASA reported an issue in Hubble's Control Unit/Science Data Formatter and that Side A of the control unit no longer supported the transfer of science data to the ground. The organization hoped to resolve the problem by transition to the redundant Side B to restore full functionality to the science instruments and operations.

The transition was a rather complex task that required five other modules to be switched as well. Also, The Side B has never been operated in space and was last activated during ground tests about 20 years ago.

Following the transition, NASA said that it has noticed new issues when the Advanced Camera for Surveys (ACS) suspended operations due to an indication that one power source in the Solar Blind Camera’s low voltage power supply failed to turn on. It was the first time NASA tried to turn on the camera since the original control unit problems surfaced and Hubble’s NSSC-1 spacecraft computer was “safed” on September 27.   

“The Solar Blind Channel is the only part of ACS in use since a power failure in January 2007 halted most ACS science observations,” NASA said.

Another failure followed while NASA was briefing its scientists on this ACS issue. The organizations said that an “undiagnosed problem” caused the NSSC-1 to stop issuing its keep-alive signal. This incident and the absence of the signal for 20 seconds was interpreted by the HST486 spacecraft computer as a failure of its Processor Interface Table (PIT) toggle test, prompting the HST486 to issue commands to safe HST’s science computer and science instruments.

Data retrieved from a memory dump suggests that there is a “potential problem in the Side B.” There were no further details, but NASA said that it is investigating the problems and will provide more details when they become available.