Space Cloudy Vistas for Big Science

By Dick Thompson

For all its first-class expertise and glorious achievement in space technology, the U.S. has had more than a fair share of bad luck, not to say tragedy. Now the quality of that vaunted technology has become a serious question. Last week, in a period of just a few days, NASA discovered that its $1.5 billion Hubble Space Telescope had been fitted with a faulty mirror and that a second of its three shuttles had sprung hydrogen leaks.

Costly and frustrating as the shuttle problem is, NASA will be able to correct it with relative ease. The agency prudently grounded not only the two faulty spaceships but the third shuttle as well, until engineers are satisfied that the hydrogen fuel system is safe. This means a wholesale rescheduling of NASA's launch program and corresponding delays in realizing all of NASA's scientific and military objectives.

The Hubble difficulty is quite something else. Unlike the shuttle, the telescope is unique. Moreover, it has already been launched and cannot be hauled back into the hangar for repairs.

When Hubble was launched in April, NASA promised that it would see the ancient universe in startling clarity, but the discovery that one of the two mirrors that form the heart of its optics had been incorrectly manufactured served mainly to focus attention on the limits of high technology. The immediate result is that for all Hubble's tremendous cost, two of its most heralded advantages -- the ability to distinguish very close objects and the knack for detecting faint light from the early universe -- are lost. Said John Logsdon, director of the Space Policy Institute at George Washington University: "It's horrible."

The visible starlight that Hubble is now able to collect and magnify is no better than that seen by landlocked observatories. It is impossible for Hubble to find a planet circling a distant star or detect a black hole at the center of a galaxy. At least 40% of the experiments planned for the telescope will have to be postponed until engineers can make lenses for the craft's instruments that will compensate for the mirror's flaw. Astronauts will then have to ride the shuttle into orbit and space walk to the telescope, where they will fit the new lenses. And getting those spectacles to Hubble may take three to six years.

Hubble never had an easy time. After the launch, engineers had to fiddle with stubborn antennas that refused to extend. When the antennas were fixed, the messages that came back to Earth indicated that the spacecraft was wobbling: when it swung from darkness to sunlight, the sun's rays striking Hubble's cold solar panels produced a minor vibration that caused the spacecraft to oscillate slowly. This motion confused instruments that were built to such precision that they could read a license plate 48 km (30 miles) away. NASA software designers are now writing programs to counteract the oscillations so that the telescope tube can be held steady.

Locating objects for the telescope has also been bothersome. An exhaustive catalog of guide stars was built into Hubble's computer memory, enabling it to identify both its position in space and the object of its interest. A programmer, however, failed to update the information properly, and for weeks Hubble was looking left when it should have been looking right. That too has been fixed with a software Band-Aid.

Such shakedown glitches were perhaps to be expected, but the difficulties with Hubble's optics were not anticipated and have been devastating. The astonishing fact is that one of the two mirrors built by Perkin-Elmer Corp. % -- engineers do not know which one -- was made to the wrong specifications. The mirror is either too high or too low by 4 microns, about 4% of the diameter of a human hair. Although tests could have detected this error on the ground, they either were never performed or failed. A government panel will investigate how the mistake was made, and the Senate has cranked up its own hearings.

Fortunately, Hubble can still do work from space that no telescope can do from the ground. It can observe the universe's ultraviolet glow, a part of the spectrum of starlight that does not reach Earth, and it will be able to study the physics of stars. In addition, large objects, such as the giant red spot and polar caps of Jupiter, will be within Hubble's range. Administrators at the Space Telescope Institute in Baltimore are now scrambling to reassign observing time for those instruments that do not rely on the mirrors. Since requests from various scientific groups for Hubble's intelligence were ten times as great as the time available for observing, the telescope will still be used constantly.

Even so, the latest hobbling of Hubble can only intensify arguments over the wisdom of funneling large portions of the nation's research budget into a few steeply expensive projects. President Bush's proposal to launch a moon-Mars mission has been stalled on Capitol Hill. Congress is uncomfortable with the $30 billion price tag for a proposed space station as well as with the planned $8 billion Superconducting Supercollider that will be built in Texas. "We're spending a disproportionate amount on big science," says California Congressman George Brown. "Any failure casts some discredit on the desirability of funding these big science projects." In the end, the saga of the cloudy mirrors and the leaky shuttles may yet reflect a clear resolution to a confounding question: How should the nation apportion its finite wealth in pursuit of scientific achievement?

With reporting by Jerry Hannifin/Washington