What's Next for Hubble
10 Jul 2009
Since the conclusion of Servicing Mission 4, engineers and scientists have been conducting the painstaking process of testing and reactivating Hubble components in order to bring the telescope back to full science operations. The ambitiousness of the servicing mission, with the installation of two new instruments, repair of two others, and the replacement of the Science Instrument Command and Data Handling Unit (SIC&DH) and a Fine Guidance Sensor (FGS), means testing, alignment and calibration activities are extensive, but much progress has been made.
On June 15, an electronic malfunction occurred in the replacement SIC&DH, which helps command the science instruments and directs the flow of data within the telescope before it is transmitted to Earth. Protective shutdowns of instruments and computer data indicated that the problem had occurred. Investigations narrowed the malfunction down to a single component, which is now functioning without issues.
The malfunction may not occur again, and the probability of damage if it did is very small, but engineers are devising protective measures to ensure the safety of Hubble's instruments in case of a repeat performance. The creation of these measures has delayed some of the regular testing and reactivation activities, including the alignment of the instruments. Hubble instruments go out of alignment when they are exposed to weightlessness for the first time and are built with mechanisms that allow engineers to adjust them from the ground, often by moving small mirrors within the instrument itself.
Each instrument contains a number of "channels." Each channel detects and processes different wavelengths. After putting all instruments into a protective safe mode while examining the SIC&DH malfunction, engineers and scientists were able to resume work on several individual channels. Others were kept inactive until safety measures could be defined and implemented.
- The Wide Field Camera 3 (WFC3) is well on its way to achieving its planned alignment and focusing milestones. Both channels of WFC3 continue to undergo focusing and alignment. The instrument has already been successfully exposed to its first light from space.
- The Advanced Camera for Surveys (ACS) was placed in protective mode two weeks ago, due to an electronics glitch. It has since been returned to operations. Testing is progressing normally and is almost complete.
- The Space Telescope Imaging Spectrograph had two channels suspended due to the SIC&DH problem, but protective measures are now in place. This instrument is expected to be back in operation by the week of July 13. One of its channels had already been approved for science operations and the other two are close to being approved.
- The Cosmic Origins Spectrograph is partway through the alignment process and internal measurements look good. One channel is being calibrated. The other channel has resumed testing after installation of protective measures related to the SIC&DH event.
- Fine Guidance Sensors were unaffected by the SIC&DH problem and continued operations and testing. The refurbished FGS installed during SM4 has been approved for use as one of the guiders for the pointing control system, and can now do its part to help position the telescope.