Hubble's vision saved

Hubble's bleary eyes can see once more as engineers have managed to get one of its main cameras back online.

Late last week, NASA engineers switched over to the space telescope's back up power supply, and reactivated the Advanced Camera for Surveys, which had been out of service for almost a fortnight. Scientific observations resumed on Sunday.

Hubble's camera went offline on 19 June. Engineers thought it most likely that the problem lay in the power supply voltages, but speculated that a cosmic event could have damaged the camera's memory. The fault turned out to be nothing so glamourous, however, with the original power supply theory proving correct.

Engineers also took the opportunity to re-calibrate the camera, while they were working on fixing the batteries. The camera will now operate at a lower temperature, reducing the amount of noise in the data.

"This is the best possible news," said Ed Ruitberg, deputy associate director for the Astrophysics Division at NASA's Goddard Space Flight Centre. "We were confident we could work through the camera issue, and now we can get back to doing more incredible science with the camera."

The Advanced Camera for Surveys was installed during a 2002 servicing mission. Its three cameras see into space in the visible, ultraviolet and infrared spectra, and its installation effectively doubled Hubble's field of view. NASA says it is pleased that it is only having to use the redundant systems now, four years into a five year mission.

Hubble is tentatively scheduled for its next service mission in 2007. But that mission is very dependent on the success of Discovery's next flight. NASA is currently reluctant to fly missions that don't visit the International Space Station. If the problems with Shuttle are not resolved, Hubble is likely to fade into the background as its gyroscopes lose power and its orbit becomes destabilised. ®