NASA, Perkin-Elmer share blame for Hubble flaw, panel says

November 26, 1990|By Robert S. Capersand Eric Lipton | Robert S. Capersand Eric Lipton,Hartford Courant

HARTFORD, Conn. -- NASA and a mirror manufacturer share the blame for a flaw that prevents the $1.5 billion Hubble Space Telescope from focusing clearly, a NASA panel has concluded after a five-month investigation.

To some extent, the failure to detect a flaw polished into the 94.5-inch Hubble mirror in 1980 and 1981 is a product of the same management climate that led to the fatal explosion of the space shuttle Challenger in 1986, said John D. Mangus, one of six members of the Hubble Optical Systems Board of Investigation.

Conditions discouraged engineers from bringing potential problems to their superiors at the National Aeronautics and Space Administration and at Perkin-Elmer Corp. in Danbury, Conn., where the mirrors were made, said Mr. Mangus, head of the optics branch of the space technology division at NASA.

"The culture has to be encouraged where you don't shoot the messenger," Mr. Mangus said. "People don't like bad news, but what they like worse is not to be told about the problems. I know it has occurred on many of NASA's projects."

An investigation into the Challenger explosion that killed seven crew members found that NASA ignored evidence of problems with O-rings for sealing the joints of the shuttle's solid-fuel rocket boosters. Investigators faulted NASA for weak quality control and found that, under intense schedule pressure, engineers sometimes failed to report problems to managers.

The immediate cause of the Hubble mirror flaw was a technician's mistake, but program managers approved the flawed quality-control program that allowed the mistake to escape detection, says the investigatory board's report, which is scheduled to be released tomorrow.

Board members would not release the report, but Mr. Mangus and other members said the report, more than a quarter-inch thick, also says:

* Mirror-testing relied too heavily on a single instrument, which had been assembled improperly. Relatively simple "sanity checks" should have done to make sure the mirror-polishing system was working properly.

* There was too little contact between those working on the mirror and NASA project supervisors who could have understood the test results.

* Quality-control inspectors lacked the expertise in optics to understand test results that showed a flaw in the mirror.

Mr. Mangus said NASA needed to develop in-house expertise in this area.

"The people in the quality-assurance area were concerned about obvious things, like if you go above the mirror with a pencil in your pocket it can drop out and chip the mirror," he said. "But they did not have the technical background in optics that is required to understand the subtleties of the things that you look for.

"It might never have occurred to them to look at the raw data, and if they had, they might never have known how to interpret what they were looking at."

NASA has acknowledged past problems and has said that management changes were made after the Challenger disaster to correct deficiencies in the agency.

However, confidence in NASA has been shaken anew in recent months because of the Hubble flaw, excessive hydrogen leaks in two space shuttles and problems on other programs. In addition, Congress said last month that it was unhappy with plans for the space station and ordered changes, and a Bush administration panel is considering the future of NASA and the nation's space program.

"NASA certainly had the overall management responsibility," Mr. Mangus said of the Hubble project. "They did not have the management system in place to penetrate far enough into the system -- otherwise this probably would not have happened."

The Hubble telescope was launched aboard a space shuttle April 24, and the focusing flaw was disclosed June 27. The investigatory committee convened July 2.

Much of the committee's report is devoted to an explanation of the basic mechanical mistakes that caused a spherical aberration to be polished into the mirror.

The mirror is flawed because a null corrector, the principal optical instrument used to test it and measure the progress of the polishing, had been assembled incorrectly by technicians working at Perkin-Elmer's optical division, which now is Hughes Danbury Optical Systems.

In addition, the report says, tests done with a second null corrector indicated that the mirror was flawed, but those test results were discounted because engineers working on the mirror were confident that their primary test instrument had been assembled so carefully that it could not be giving false readings.

"You would dearly have loved to have someone more thoughtful about what was being seen there when the warning flags went up," said Roger Angel, an astronomy professor at the University of Arizona and a member of the NASA investigatory panel. "But you could also fault something that set in motion a procedure that allowed this to happen."

Despite the flaw, NASA scientists have reported increasing success in using the telescope, which has produced better images than can be made from instruments on Earth because it is above the Earth's atmosphere.

But the telescope has fallen far short of its principal goal of seeing out to the farthest reaches of space to explore the origin of the universe.

Scientists have been planning for months to install a new Wide Field-Planetary Camera -- the Hubble's principal instrument -- on the telescope during a 1993 space shuttle mission.

Although the planned mission could restore some of Hubble's capacity, a newer plan might allow the telescope to accomplish about 90 percent of its original mission. This plan calls for installing not only a new main camera but also a device with five pairs of mirrors that could correctly focus light for analysis by three of the Hubble's other four instruments.

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