Hubble Trouble and Shuttle Fuel Leaks Raise NASA Questions

SPACE scientists expect to have soon a more detailed assessment of how much scientific use they can get out of the flawed mirror in the Hubble space telescope. Those closely involved with the project are much more optimistic now than last week that most of the telescope's work - virtually all of it under the best scenario - can be recovered.

But the stunning news last week that one of the mirrors in a $1.5 billion telescope was cut at the wrong curvature has revived questions about quality control and overreaching in the American space program raised by the Challenger accident in 1986.

As if for emphasis, a liquid hydrogen fuel leak was discovered in a second space shuttle June 29, grounding the fleet of three indefinitely until the cause is found.

The scathing charges of the Challenger aftermath - that the space program is built upon an unrealistic hope that shuttles will provide relatively easy, routine access to space - are cropping up again.

``I am very concerned that we learned those lessons,'' says Louis Friedman, executive director of the Planetary Society: ``the remoteness of space and the difficulty of working there.''

To Mr. Friedman, the problem has its roots in the overpromising of easy access to space. ``The hype said we were going to flip a switch [on the Hubble], there's the edge of the universe, there's the beginning of time, here's what it looks like,'' Friedman says.

Plenty of complications

The Hubble telescope, like the Earth Observation System known as Mission to Planet Earth and the space station, are built around access by space shuttles.

At the very least, the members of Congress who set National Aeronautics and Space Administration budgets every year are going to be asking more questions about how much NASA can take on. The Bush administration wants to push forward to manned moon and Mars expeditions.

``It has sobered everybody up that these are complicated things,'' says a congressional aide.

In a hearing last week, Sen. Albert Gore Jr. (D) of Tennessee, chairman of science, technology, and space subcommittee of the Senate Commerce Committee, accused NASA of biting off more than it could chew with these ambitious projects. The result, he said, was that quality control had suffered.

The flawed mirror in the Hubble was ground a decade ago by the Hughes Danbury Optical Company to incorrect specifications.

The mirrors in the telescope were tested individually, but not all in sequence. The ``end-to-end'' test was considered too expensive to be worthwhile, said Lennard Fisk, head of NASA's science office.

NASA is setting up a board of inquiry headed by Lew Allen, director of the Jet Propulsion Laboratory in Pasadena, Calif., to find the cause of the error.

Scientists at the Space Telescope Science Institute, a consortium of astronomers with project proposals for the telescope, are growing more optimistic about the Hubble since last week.

Contrary to some early reports, the Hubble's workhorse, wide-field, planetary camera is not useless, says senior scientist Eric Chaiffon. Most uses can be recovered as long as scientists are willing to expose their pictures up to eight times longer than planned.

Hubble limited, but useful

The camera will be less usable in crowded viewing fields or in viewing faint objects, Dr. Chaiffon adds, and the faint-object camera will not deliver as sharp a picture at the narrowest aperture settings. Some other devices, such as a spectrometer, have not been affected at all.

Scientists hope to repair the telescope with a visit by space shuttle in 1993. Chaiffon calls it a ``very easy fix'' that involves a correcting plate the size of a nickel.

In the meantime, he says, the Hubble will still remain busy with ``absolutely unique science.'' NASA planned to do the top-priority observations first, while the system was most likely to be at peak performance. Those observations will now have to await the repair.

But Chaiffon and his colleagues are convinced that the Hubble can still eventually perform 95 percent of its work, and all of the most important projects.

He notes, however, ``we may not ever be able to make up for this in terms of public perception.''