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The Hubble Space Telescope, seen here during its initial deployment in 1990 by the Space Shuttle Discovery, appears to have been repaired after another near-death experience.
By Daniel Cléry
The iconic but old Hubble Space Telescope appears to have been resurrected after being shut down for more than a month following a computer glitch. Science learned that following a switch from the operating payload control computer to a standby device in the past 24 hours, Hubble operators have re-established communications with all telescope instruments and plan to return them to normal operation today.
“Hubble is back! Tom Brown, head of the Hubble mission office, emailed staff at the Science Telescope Science Institute (STScI) at 5:56 am this morning. “I am delighted to see Hubble begin to explore the universe again.”
The problems began on June 13 when the payload computer that controls the scientific instruments and monitors their health detected an error communicating with the instruments and put them into safe mode. Hubble operators initially thought that a memory module was involved, but switching to one of the three backup modules produced the same error. Various other devices were investigated and excluded as an issue when the error persisted.
It was ultimately decided that the entire Scientific Instrument Data Processing and Control Unit (SI C&DH), of which the payload computer is a part, should be switched from the instrument currently in operation. operation with the back-up instrument. Staff performed the procedure with equipment on the ground over the past week and a full examination was done to ensure it could be done without damaging the telescope in any other way. Shortly before the change began yesterday, NASA announced that it had identified the Power Control Unit (PCU), which is part of SI C&DH, as the source of the problem. The PCU is supplying constant voltage to the payload computer and either it was providing voltage outside the normal range or the sensor that detects the voltage was giving an erroneous reading. As there is a spare PCU as part of the SI C&DH, the change has been made.
Brown told his colleagues this morning that “Hubble has been successfully recovered in normal mode on the A side of the Science Instrument Command and Data Handler (SIC & DH). It was the first time that we were able to progress beyond the problem we were seeing on the B side. ”He said if everything continues normally, Hubble will restart science observations this weekend.
Astronomer Richard Ellis of University College London, who spoke with Science when the news came he said, “You have to tell everyone how nervous we all were! The telescope, he says, has always been “a truly global facility. Everyone is a Hubble friend. It is unique.
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