Hubble's flaws: looking for the source.

Hubble's flaws: Looking for the source

Only "three or four" NASA inspectors oversaw the Hubble Space Telescope's optical system during construction, former NASA administrator James Beggs told Congress last week. "We would normally have had many more people in the plant," but management problems, budget cuts and a Department of defense directive all conspired to limit NASA's inspection force, he said.

Testifying before the Senate appropriations subcommittee that oversees NASA spending, Beggs acknowledged that the limited number of inspectors could "have had some impact" on NASA's failure to prevent or detect a serious flaw in one of Hubble's two mirrors (SN: 7/7/90, p.4).

Efforts to reduce cost overruns, as well as the necessity of dividing NASA's inspection work force between two main contractors may have hampered the agency's efforts to properly inspect Hubble's mirrors, Beggs said. But seriously compounding these problems, Beggs said, was the military's request that NASA limit its personnel at the optics contractor in Danbury, Conn. -- Perkin-Elmer Corp., now Hughes-Danbury Optical Systems, Inc.--because of classified U.S. defense projects the company handled.

A 1983 investigation by the House Appropriations Committee bolsters Begg's assertions. It found that because the military "wished to limit the number of NASA personnel 'penetrating' contractors who were working on classified projects," NASA established an initial "cap" of 90 people for the Space Telescope program -- less than half the number the agency usually allocates for large projects. After that cap was lifted in 1979, NASA's Hubble staff grew to exceed 200. However, the congressional investigators concluded, "NASA was slow in reaching this level, and inadequate contractor monitoring resulted."

Roger Angel, a telescope-mirror designer at the University of Arizona in Tucson, and member of a panel appointed by NASA to investigate Hubble's troubles, is concerned the flawed mirror may have escaped detection "not so much because of a lack of people, but because of a lack of information flow." On his panel's visit to Hubble's mirror maker, Angel plans to compare data from several tests made with either of two "null" lenses, used to help detect mirror imperfections (SN: 7/21/90, p.39). Because the two null lenses have different optical properties, Angel told SCIENCE NEWS it was "unlikely" that each could have been mistakenly constructed so they both missed the mirror defect. But he adds that the company may not have compared final measurements taken with one of the null lenses to those obtained using the other.

Efforts to pinpoint technical and procedural errors "is not a witch hunt," according to William G. Fastie, an astronomer with Johns Hopkins University in Baltimore. Says Fastie, involved with a NASA working group formed in 1977 to oversee Hubble's construction, "If we can detect the problem, we can design the most accurate method to correct the flaw."