Article here

A major failure of the “Side A” control system on the Hubble Space Telescope ... has shut down Hubble’s science operations, and is currently unable to send data back to Earth. Attempts will be made to switch to the “Side B” control system later this week.

Switching over to the Side B control system has never been attempted in the lifetime of the telescope, although it is hoped the process will work, and return Hubble back to functionality.

“Side A of the CUSDF (Control Unit/Science Data Formatter) in HST went into safe hold, this means science operations have stopped. The spacecraft is still operational but unable to operate the instruments,” noted information acquired by L2.

“Attempts to recover the A side have failed so the project is now working to transfer science operations to the B side, this requires transferring the whole spacecraft from Side A to Side B so its a significant operation.

“Side B side has not been operated on orbit, for HST’s entire on orbit service life it has operated on Side A. However, the B side was fully tested before launch.

“The plan as of now is to complete the transfer to the B side later this week. The details for this will be provided later by the project.

...

“If the B side does not come on line then ... there is no way to get science data down. ”

(references to inappropriate topics deleted)

Obvious question: Can this be fixed on the upcoming repair mission?

Also from the article:
"Evaluations are taking place on whether a replacement control system - to return redundancy to the telescope - will now be required to launch with STS-125....This would delay STS-125 until 2009."

Obvious indeed. What is also obvious is that it's in breach of forum rules.

Please read http://www.unmannedspaceflight.com/index.p...;showtopic=5444
Specifically

"The hubble servicing mission is off topic"

Thus, topic closed, several posts deleted.