Hubble Review Delayed One Week

A review of a faulty Hubble Space Telescope system that was planned today has been pushed back a week, to next Friday, NASA officials say.

Managers are taking a cautious approach to fixing a computer problem that forced postponement of Atlantis' Oct. 14 launch on the final mission to service Hubble, and which has severely curtailed the observatory's ability to make scientific observations since last weekend.

A failure occurred last weekend with the telescope's Control Unit/Science Data Formatter, which formats and sends commands to the observatory's main flight control computer as well as its science instruments.

Managers plan to switch operations from the unit's Side A, which had worked flawlessly since the telescope was deployed in 1990, to its Side B. But the switchover process is a challenging one.

"We want to make sure we're not going to be doing any harm to Hubble by actually doing this," said Susan Hendrix, a spokeswoman at NASA's Goddard Space Flight Center in Maryland, home of the Hubble program.

Hendrix said plans for when and how to make the switchover should be more clear by Oct. 13, following next Friday's test readiness review.

You can read a primer on Hubble systems is here: HSTSYSTEMS. See Section 5.5 for details on the Control Unit/Science Data Formatter, which is part of the Science Instrument Control and Data Handling system.

NASA now plans to replace the faulty hardware when the mission flies. But first it must go through rigorous testing, and astronauts must be trained on how to replace the equipment.

That operation is expected to take up to two hours of what was already a packed schedule during five spacewalks.

If testing goes according to schedule, officials expect to deliver the replacement unit to Kennedy Space Center in early January for addition to the rest of the Hubble payload.

Workers are beginning to remove that payload from Atlantis' cargo bay this weekend. It will be returned to storage by Oct. 14 at the space port's Payload Hazardous Servicing Facility, except for batteries that will be shipped back to Goddard.

Atlantis is tentatively scheduled to be rolled back to the 52-story Vehicle Assembly Building on Oct. 20. It is not expected to launch before mid-February at the earliest.

Despite the delay, Hubble officials say they feel fortunate that the problem surfaced before the fifth and final servicing mission launched, giving them an opportunity to fix a problem that could have rendered the mission useless.

"That would have been a real blow to the team and all the scientists expecting to use Hubble," said Hendrix. "Now, there's something we can more than likely do about it."

IMAGE NOTE: Click to enlarge the image of the Hubble Space Telescope, recorded by the crew of STS-103 during a servicing mission in December 1999. You can also click the enlarged images to get even bigger views.