Hubble repair mission delayed

By Frank D. Roylance

September 30, 2008

NASA has delayed plans to launch a repair mission to the Hubble Space Telescope next month because a science data computer stopped working over the weekend, officials said yesterday.

The mission, planned for launch Oct. 14, will not launch before mid-February, a delay that will cost the Hubble program at least $10 million a month, according to NASA officials.

In the meantime, the telescope is unable to transmit any scientific data to the ground.

Engineers at the NASA Goddard Space Flight Center in Greenbelt are working this week to transfer the work of Hubble's malfunctioning science data downlink computer to a backup system so they can resume science operations within a few weeks.

But the backup has not been tested since Hubble was launched in 1990, and it won't be known for several days whether the transfer has succeeded, said Susan Hendrix, a spokeswoman for the Hubble program at the Goddard center.

Even if it does work, NASA still wants to delay launch of the servicing mission so that engineers can plan for an attempt to replace the failed computer during the rescheduled shuttle mission.

The delay comes as a disappointment for hundreds of scientists and engineers in Maryland who work with Hubble at Goddard or at the Space Telescope Science Institute in Baltimore, and for thousands of scientists around the world who use the observatory.

But if astronauts can replace the failed computer and its backup when the servicing mission does finally fly next year, they will restore redundancy to the telescope and increased its reliability and life expectancy in orbit, said Matt Mountain, director of the space telescope institute.

"The worst-case scenario would have been if this had failed just after [the servicing mission]. There is a silver lining," Mountain said.

Hendrix said the problem arose just after 8 p.m. Saturday when "Side A" of the telescope's scientific data downlink computer - called the Control Unit/Science Data Formatter - experienced what she called a "hardware failure."

The telescope went into a "safe" mode, which also shut down the scientific instruments.

Side A of the computer had been operating reliably since the observatory was launched in 1990. By transferring to Side B, engineers hope to restore science observations and downlinks while they work on plans to replace the whole unit.

But the backup system hasn't been switched on in more than 18 years in space, and engineers aren't certain it will work.

The replacement unit on the ground is just as old, but it has been in careful storage since 1990. It was tested once, in 2001, and worked well, said Preston Burch, the Hubble program manager at Goddard. But it will have to undergo thermal vacuum and vibration tests before it can be qualified for flight. That could take until January.

The long-awaited $900 million servicing mission is to be the final visit by astronauts to the orbiting telescope. Their goal is to extend its working life for at least five more years and to expand its scientific capabilities.

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