NEWS ANALYSIS : Shuttle Delays: Is Versatile Craft Simply Too Complex?

For the scientists and engineers who had hoped to see the Hubble Space Telescope in orbit today, the scrubbing of Tuesday’s launch just four minutes before liftoff was another disappointment on a long, tortured trail of frustration.

But for hundreds of others at the Kennedy Space Center whose lives revolve around the space shuttle, it was just par for the course.

More often than not, launches are scrubbed or at least delayed during the final countdown at the huge spaceport because the shuttle is a unique transportation system with literally millions of things that can go wrong. Invariably, some of them do, as with a hydraulic system valve on Tuesday.

Critics have long argued that the shuttle is just too complex. They contend it is an engineering nightmare that was designed to be all things to all people--from a space truck that delivers cargo to low Earth orbit to a space laboratory that allows scientists to carry out experiments free of the Earth’s gravity.

The shuttle is simply the most sophisticated flying machine ever built, and experts have speculated that it is at least 10 times more complex than the Apollo spacecraft that carried astronauts to the moon.

Caltech planetary scientist Bruce Murray, former director of NASA’s Jet Propulsion Laboratory and a longtime critic of the shuttle program, has argued over the years that the shuttle is so complex that it is not suited for many of the functions it is called on to perform, and it is a drain on the space agency’s resources. The 175,000-pound vehicle, about the size of a DC-9 jetliner, is a hybrid designed to fly both in the near vacuum of space and through the Earth’s atmosphere, and it was the first manned vehicle built to do that.

With the space telescope, the shuttle is to fulfill the ultimate goal it was intended to reach: deliver a complicated piece of hardware to space, and then return over and over in the years ahead to service the telescope and even replace its instruments.

As Bruce McCandless, one of the Discovery’s astronauts, said in a recent interview: “We are the only ones in the world who can do that.” And no one else is likely to be able to for many years in the future. The Soviet Union is the only other country with a reusable “spaceplane,” but it has flown only once on an unmanned test flight and there are serious doubts that the Soviet program will become operational in the foreseeable future. European countries hope to build such a craft sometime, but that program is mired in controversy over its high cost, and it will be many years before the Europeans have a manned space vehicle of their own.

That leaves the U.S. space shuttle as the sole vehicle in the world capable of doing what it will be required to do throughout the history of the Hubble Space Telescope.

But that capability has not come easy, and every launch will continue to be a roll of the dice. In hopes of loading the dice in their favor, officials with the National Aeronautics and Space Administration have cranked in so many safety factors that it is somewhat surprising that the shuttle ever gets off the ground at all.

There are at least a dozen ground controllers who can squelch the countdown at any moment. They draw their data from scores of sensors spread all over the shuttle that tell everything from a slight change in temperature in scores of critical components to the flow of fuel through dozens of valves.

The sensors monitor a total of 49 different engines. That includes three main engines fueled by the orbiter’s enormous external fuel tank strapped to its belly, two orbital maneuvering engines and 44 “reaction control” engines that allow the crew to change the orientation of the craft while in orbit.

The shuttle also uses two solid rocket boosters, which NASA had thought were the safest parts of the propulsion system until the Challenger disaster in 1986 proved that wrong. It was a failure in the joints of those boosters that led to the Challenger’s explosion shortly after liftoff.

That level of complexity, critics of the shuttle maintain, grew out of the desire to create a single vehicle to perform an unrealistic number of tasks, and it means that the system will always be plagued with problems because there are simply so many things that can go wrong.

Yet despite the fact that every shuttle that lifts off the pad has a few malfunctions, the reason for most delays lies in the weather, not the hardware.

In many ways the Kennedy Space Center is in just the wrong place because Florida weather is subject to rapid changes. For a successful launch, winds cannot exceed certain levels from certain directions, and even a little rain will force the countdown to be halted because raindrops would damage the tiles that protect the shuttle from high temperatures during descent.

Not only must the weather be satisfactory in Florida, but also at various landing sites scattered around the world. During an emergency, the shuttle might have to land in Europe or Africa, and designated airstrips must have satisfactory weather for the shuttle to be cleared for launch.

In addition to the complexity of the shuttle, the launch schedule that NASA hopes to maintain in the coming months is so crowded that the delay in the Discovery’s launch could affect other flights for many months.

Officials at Kennedy were saying Wednesday that they expect the launch to be delayed at least 10 days, and possibly as much as two full weeks. In addition, the space telescope’s batteries will have to be recharged before launch, and there is a remote possibility that the 12-ton telescope will have to be removed from the cargo bay of the shuttle.

And Discovery is to be used for a critical mission in October to launch the Ulysses spacecraft to study the sun. That is a European spacecraft, and if it fails to meet a small launch window in October the launch would be delayed for more than a year. That is something NASA wants to avoid at almost any cost because the Europeans are partners on other missions, including the Space Station, and not everything has gone the way the Europeans had wanted.

The Ulysses, for example, is more than four years behind schedule because of the Challenger disaster.

So it now appears that a small valve in a single hydraulic system that helps power the shuttle’s steering system, among other things, has thrown a monkey wrench into the works that could mess up a lot of things for a lot of people.

And that, for many involved in the U.S. space program, is par for the course.