During the night of Oct. 15, Space Telescope Operations Control Center engineers at NASA's Goddard Space Flight Center turned on and checked out Side 'B' of Hubble's Science Instrument Control and Data Handling (SIC and DH) system.

Subsequently, the Advanced Camera for Surveys (ACS), Wide Field Planetary Camera 2 (WFPC2) and Near Infrared Camera and Multi-Object Spectrometer (NICMOS) instruments were retrieved from safe mode to establish that each has a working interface to the Side B SIC and DH.

The instruments were then commanded back into safe mode, and will remain in that state until the SIC and DH begins issuing commands to them later today.

Around noon today commands to recover Hubble's science instruments from their safe modes will begin and internal exposures and calibrations of the telescope's science instruments will occur before midnight Thursday.

Scientists at the Space Telescope Science Institute in Baltimore should complete their review of the internal exposures by noon on Friday, October 17. This procedure involves collecting and comparing baseline exposures previously supported by Side A of the SI C and DH to new exposures supported by Side B.

This review will be one last check of the "transparency" (non-impact) of switching to the redundant spacecraft electronics the Hubble team activated on Wednesday.

A full schedule of science observations with the WFPC2 camera, ACS' Solar Blind Channel camera, and the Fine Guidance Sensors will resume early Friday morning.