Hubble weathers ups and downs
Posted: Friday, October 17, 2008 1:25 PM by Alan Boyle
NASA
Engineers man their stations at the Space Telescope Operations Control Center as commands are transmitted to Hubble's command and data-handling system.
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The revival of the Hubble Space Telescope started out going "exactly as we hoped," a NASA spokesman said, but engineers had to put a hold on the operation after they saw two anomalies in electronic systems onboard the telescope.
Hubble's science operations went on the blink last month when the main system for handling commands and data going back and forth between the telescope's instruments and the ground failed. Controllers could still send commands up to Hubble and receive diagnostic readings, but the flow of imagery that made the telescope famous was cut off.
The sudden, unexpected snag forced the postponement of the space shuttle Atlantis' final service call, which was due for launch this week.
To revive Hubble, engineers at NASA's Goddard Space Flight Center devised a plan to switch the flow of data from the main system that the 18-year-old telescope had always used, known as Side A, to a never-before-used backup system known as Side B. The space agency's top management gave the go-ahead for the remote-controlled switchover on Tuesday, and engineers went to work on Wednesday.
Engineers checked out Side B for the first time on Wednesday night, NASA spokesman Ed Campion told me Thursday. "All that went exactly as we hoped, so after that, the Advanced Camera for Surveys and the Wide Field Planetary Camera 2 were retrieved out of safe mode to establish that each of them has a good working interface to Side B," he said.
Hubble's reconfigured electronics passed that test as well. "Everything worked the way we hoped it would," Campion said. "Now we're going to send commands to begin internal exposures and calibrations of the science instruments."
The calibration data would have been used to check that Side B was functioning just as well as Side A was before the breakdown. But that part of the operation mustn't have went as well, according to a NASA update issued Friday:
"Activitation of the Hubble Space Telescope science instruments and resumption of science observations have been suspended following two anomalies seen in systems onboard the telescope on Thursday. All of the telescope's payloads are back in safe mode condition while engineers perform troubleshooting."
NASA is due to provide further details later today.
Every hiccup in Hubble's status is felt deeply by the team working to get the telescope back in business. Before the latest glitch, Susan Hendrix, a NASA spokeswoman who specializes in following Hubble operations, told me that she felt a personal stake in the telescope's ups and downs.
"Hubble's been very near and dear to me," she told me Thursday. "It's kind of like an adopted child."
Even if Hubble resumes science operations, the child will still have to undergo some follow-up surgery: A spare unit is currently being tested at Goddard, and if that checks out, it will likely be brought up on Atlantis for installation (along with lots of other Hubble goodies) next year. Even when the new unit is in place, Hubble data will continue to flow through the Side B electronics, and Side A would become the backup. That's in line with a common-sense rule for engineers: "If it's no longer broke, don't try fixing it again."
Keep up with the latest news about Hubble's revival by checking the status reports on NASA's Hubble mission page. There's even an RSS feed that you can add to your feed subscription list (along with the feed for Cosmic Log, of course). And if you need to be reminded why Hubble is worth saving, check out our space gallery and especially our audio slide show retelling "The Hubble Story."
This is an updated version of an item that was first published at 12:36 p.m. ET Oct. 16.
