There's good news and bad news this week regarding the Hubble Space Telescope.
The good news is that NASA's 18½-year-old flagship has begun observing again, one month after data-handling electronics failed on September 27th. The loss of the Control Unit/Science Data Formatter (CU/SDF) never really threatened the observatory's mission, but it's taken flight engineers a few weeks to complete the switchover to a redundant "B" unit on board.
"We're operating just fine on side B," reports Preston Burch, HST program manager at NASA's Goddard Space Flight Center. So far two instruments have been powered up, including the Wide Field and Planetary Camera (WFPC) 2. A third, the Near-Infrared Camera and Multi-Object Spectrometer (NICMOS), should resume operation soon after its cooling system is restarted on November 10th.
To celebrate Hubble's return to duty, NASA and the European Space Agency released a WFPC 2 image of Arp 147, a pair of interacting galaxies in the constellation Cetus some 400 million light-years away.
The bad news is that astronauts will have to wait a few more months before rocketing into orbit abaord STS 125, the fifth and final Hubble servicing mission. The flight had been slated to begin October 14th — with the Space Shuttle Atlantis on the pad awaiting launch — when the malfunction occurred.
Initially NASA managers announced a delay until February so that a replacement unit could be readied for flight. The CU/SDF is part of a larger assembly called the Science Instrument Command and Data Handling system (SIC&DHS). Now they say the spare won't be fully inspected and tested until April, likely pushing liftoff of STS 125 to next May at the earliest.
Part of the delay stems from the realization that the spare SIC&DHS, which has been in storage since 1991, had a few pieces missing. Over the years engineers have removed a few parts for use in ground tests of other systems, and it's going to take extra time to get it put back together — a detail missing from NASA's press release.
Another issue is that the replacement's A-side CU/SDF didn't work when technicians attempted to turn it on last Friday. "We're looking at workmanship and parts problems to troubleshoot this glitch," Burch told reporters today.
The silver lining in all this is that the malfunction occurred before the repair mission, not after it, and that it can be fixed with relative ease. Replacing the SIC&DHS should add only about 1½ hours of spacewalking time, which the astronauts plan to squeeze into their already lengthy "to-do" list.