Science News Magazine

Washington, D.C.


Ron Cowen, 202/872-5119

For Immediate Release: Nov. 5, 1999

Y2K Problem Looms in Hubble Repair

[Science News (a weekly news magazine), Nov. 6, 1999 issue]

By Ron Cowen

Space agency officials have their fingers crossed that the shuttle will roar into space on schedule next month, carrying astronauts who will
replace three failed gyroscopes on the Hubble Space Telescope. Already postponed 2 months, the repair mission is critical: If one more of
Hubble’s six gyroscopes fails, the telescope won’t be steady enough to observe the heavens.

There’s another reason the space agency hopes the mission won’t miss its December launch window and get bumped into next year, SCIENCE NEWS
has learned. Because planning time for the Hubble mission was unusually short, NASA hasn’t certified that the software the shuttle will use to
navigate and rendezvous with Hubble meets year-2000 (Y2K) standards.

The now-infamous Y2K problem stems from the use of two digits instead of four to represent the year in computer programs (SN: 1/2/99, p.
4). Systems continuing to use that shortcut may not know whether 00 means the year 1900 or 2000, creating the potential for serious errors.

Scheduled for launch between Dec. 2 and 14, the 9-day Hubble-repair mission will include four space walks. Although anxious about the
schedule, “we have no reason to believe that NASA can’t get the mission off on time,” says Steven Beckwith, director of the Space Telescope
Science Institute in Baltimore, which operates Hubble. If inclement weather or other
circumstances force the mission to forgo a December launch, however, the Y2K factor could loom large in efforts to quickly reschedule.

If tests now under way reveal that the NASA software will need only minor modifications to be Y2K-compatible, a postponed mission could fly as
early as mid-January. But if the software, essentially the same used to coordinate Hubble repairs in 1997, has to be replaced with a newer
version, the fix could delay the launch by 4 months, says Denny Holt, manager for the Hubble mission at NASA’s Johnson Space Center in Houston.

Holt notes, however, that there’s only an “outside chance” that the old software would have to be scrapped, causing such a major delay. So far,
tests have not uncovered Y2K-related problems. The analysis, however, won’t be completed until next month.

Hubble has had only three working gyroscopes since January and a fourth could fail at any time. In announcing plans for the repair mission last
March (SN: 3/27/99, p. 203), the agency had pushed for the earliest launch possible, an October date. Wiring problems discovered in the
shuttle, however, forced the mission to be rescheduled to December.

In choosing the earliest launch date, the agency hoped to avoid what NASA chief scientist Edward J. Weiler called a “science emergency.” Each
month that the telescope lies dormant, about $20 million in operational costs would go to waste.

To save time, NASA decided last spring to use the same software that successfully navigated the shuttle during a Hubble repair mission 2 years
ago. They had estimated that testing the old software for Y2K problems would have added another 6 months to the planning time, Holt says. If
modifying the program now proves necessary, he says, the experience acquired in certifying Y2K compatibility for a newer version of shuttle
software should make that task easier.