The investigators' final report on the malfunctioning Hubble Space Telescope, which was released yesterday, tells a story of missed opportunity and miscommunication, with NASA officials failing to provide even rudimentary supervision of technicians who three times ignored tests that uncovered the crucial flaw that now plagues the $1.6 billion telescope.
The investigating team concluded that both the National Aeronautics and Space Administration and its main contractor failed to monitor in any detail the manufacture of the telescope's most essential components, the two mirrors that gather and concentrate starlight from the heavens.
"Why was the problem not detected?" said Lew Allen, head of the investigation and director of NASA's Jet Propulsion Laboratory in California. "The answer to that question is not a particularly happy one."
The report and interviews with the investigating team reveal that the misshapen mirror aboard the orbiting observatory was built by a group of technicians who had never before made such a large and uniquely shaped mirror, at a time a decade ago when the entire Hubble program was in disarray.
Yet, these same technicians operated a "closed shop" and denied access to outside experts and overseers, according to the investigation. Even NASA's lone quality-control officer at the contractor's facility was not allowed to witness key tests done on the mirror. Moreover, Allen noted that even if NASA's man on the scene had been allowed to monitor the tests, he was not an optics expert and would therefore have been incapable of understanding the data that pointed toward a major flaw in the telescope's main mirror.
Soon after the long-delayed Hubble Space Telescope was launched in April, its handlers detected what optical experts call a spherical aberration in the orbiting observatory's main mirror. This aberration blurs the telescope's sight and has dramatically reduced its ability to see very distant stars, as well as celestial objects found in visually confusing clusters. These were to be two of Hubble's main objectives.
Allen and his fellow investigators earlier reported that the manufacture of the telescope's main mirror was botched because a simple measuring rod was misused. The rod, which was a fraction of an inch off the proper setting, was used to adjust a piece of testing equipment called a reflective null corrector, which uses light reflected off the mirror to guide the grinding of the mirror.
The investigating team reported yesterday that on three occasions, technicians at the Perkin-Elmer Corp. in Connecticut detected something wrong with the mirror.
"There were at least three cases where there was clear evidence that a problem existed," Allen said. "And they were dismissed."
In the first case, special washers had to be added to the reflective null corrector to make it focus, a clue that should have tipped off technicians that something was amiss.
In the second and third cases, test equipment believed to be less accurate than the reflective null corrector actually detected the spherical aberration. And on at least two other occasions, there were signs that something was very wrong with Hubble's main mirror.
These problems were discussed among employees at Perkin-Elmer who were manufacturing the mirrors, but according to the Allen investigation, they were never presented to anyone at NASA, nor were they raised with senior scientists and engineers at Perkin-Elmer.
Perkin-Elmer, which is widely reported to have built similar mirrors for spy satellites, won the contract to make Hubble's optics largely because of its expertise in designing and manufacturing mirrors. Yet, according to members of the investigating team, Perkin-Elmer's leading optical expert, a man who literally wrote the textbook on testing large mirrors, was never informed of the tests that revealed the flaws.
The troubling test results were ignored because technicians at Perkin-Elmer believed that they were less accurate than the test performed by the flawed reflective null corrector, the device in which both Perkin-Elmer and NASA placed absolute confidence.
NASA officials say that the management problems that led to both the Hubble fiasco and the Challenger disaster have been overcome. Refocusing the Hubble mirror, however, will require a space shuttle flight and a space walk.