Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: FRIDAY, June 15, 1990 TAG: 9006150271
SECTION: NATIONAL/INTERNATIONAL PAGE: A-1 EDITION: STATE
SOURCE: Los Angeles Times
DATELINE: ALBUQUERQUE, N.M. LENGTH: Medium
In a frank discussion with scientists attending the American Astronomical Society here, the telescope's chief engineer, Gene Oliver, said one of the most vexing problems is an unacceptable level of vibration caused by the changes in heat and cold as the telescope orbits Earth. "Without resolution" of that, he said, "we do not have a space telescope."
In addition, the telescope at times appears "confused" over which stars to focus on.
He quickly added, however, he believes that even the most serious problems will be solved, although they are proving more difficult than had been expected.
Taking care of complex problems with the fickle observatory is particularly difficult because it is in orbit, where it is expected to give scientists the clearest pictures they have ever had of some of the darkest objects in the universe.
"You can't just reach over and twist a knob" when something goes wrong, noted James Westphal of the California Institute of Technology, one of the telescope's principal scientists.
Engineers also have to be careful not to damage the telescope while trying to make improvements. "It's kind of like changing a sparkplug while you are driving down the road," Oliver said. "You've got to be careful."
All of the principal scientists on the telescope were asked specifically during a news conference if they were concerned that the problems might degrade the quality of the data they expect. All insisted they believe that the engineers will solve the problems and the telescope will eventually work as advertised.
However, Oliver, who is now the deputy project manager for the Hubble Space Telescope, made it clear that engineers will have their hands full as they try to work out at least four major bugs.
The vibration problem occurs every 90 minutes when the telescope passes from "night" to "day" as it orbits the Earth. The sudden change in temperature causes the long solar panels on each side of the spacecraft to vibrate, and that makes the entire vehicle "jitter" for up to 20 minutes.
Engineers believe the solar panels vibrate a little more than had been expected, and the control system designed to dampen the vibration is overreacting. It should be possible to resolve the problem by changing the computer commands in the craft's software, Oliver said.
Oliver said it has also proved very difficult to lock the instrument on the right targets, and sometimes it just drifts in confusion.
"We're really fighting this one," he added. "We're just beginning to understand it."
by CNB