Hubble, despite flaw, is revealing universe, NASA scientist says

April 23, 1991|By Luther Young

A year after it was launched into Earth orbit with a seriously flawed main mirror, the Hubble Space Telescope is the "best optical telescope" in existence, according to NASA's program scientist for the $2 billion observatory.

But Dr. Edward Weiler said yesterday he was concerned "how few people even know Hubble's working. It's going to be a long time" before the public understands the telescope is producing good science despite the flaw that hinders focusing on faint

celestial objects.

During a telephone conference held from Goddard Space Flight Center to mark the launch last April 24, Dr. Weiler attributed the mirror problem to "a dumb human error, probably by two or three people out of 10,000" involved in Hubble's complex design and manufacture.

An inquiry following discovery of the flaw concluded that a device used to measure the 8-foot mirror's prescription during polishing was improperly assembled by workers at the Perkin-Elmer Corp. of Danbury, Conn., now known as Hughes Danbury Optical Systems Inc.

"The lesson learned was that we need more checking and cross-checking of checkers" by knowledgeable overseers on future projects, he said. NASA was criticized in the investigation for accepting the manufacturer's decision to disregard results from another test, which revealed the flaw.

To correct for Hubble's fuzzy vision, a space shuttle will carry aloft in late 1993 a prescription replacement for the main camera, and NASA will decide next month whether to proceed with a $30 million to$40 million repair, known as COSTAR, for three other instruments aboard.

In addition, the repair mission will replace the two power-generating solar panels built by the European Space Agency, found to have a design flaw that produces a "jitter" whenever the spacecraft passes between day and night on its orbit.

The telescope is about 50 percent through the "science verification" phase of instrument check-out, a process originally expected to end seven months after launch and now targeted for completion in November.

"We're able to focus on objects 10 million times fainter than the human eye can see, and we hope to get to 250 million times fainter," Dr. Weiler said. "The universe is even more complex than we dreamed. Almost everywhere we point the telescope, we find something bizarre."

High points among Hubble observations include close-ups of a rapidly moving storm on Saturn and a spectacular ring left behind by the explosion of a supernova in 1987. Upcoming images of Jupiter will rival in detail the fleeting photos taken by the Voyager spacecraft, he said.

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