It is to be a scientific showcase - an orbital laboratory bristling with the latest know-how and the prospect of advancing manned exploration in space. But delays in the launching of the world's first reusable orbiting laboratory - the European-designed and built Spacelab - have punctured at least a few of the high-flying expectations surrounding its maiden voyage.
Spacelab was to lift off aboard the US space shuttle Columbia last Friday Oct. 28. But problems with one of the shuttle's two booster rockets have put the craft back in the hangar for at least one and perhaps four months.
A late November launch would mean different lighting and atmospheric conditions from those expected for an October mission - and thus would affect some of the experiments for the nine-day voyage.
Officials of the National Aeronautics and Space Administration (NASA) and the European Space Agency (ESA), joint sponsors of the mission, are trying to reduce the adverse impact of the delay. They are juggling the sequence of experiments to coincide with different orbital conditions. They expect that some tests originally planned may be reflown on later Spacelab missions.
''We have successfully rearranged things so the impact is significantly less, '' says Dr. C.Richard Chappell, the chief mission scientist.
Of the 70 experiments to be carried out, 10 are expected to be affected by a delay. None will be scrapped altogether, NASA scientists say, but data gleaned from a few astronomy and earth observation tests will be reduced anywhere from 10 to 50 percent.
For the Europeans, the delays are becoming all too familiar. ESA has put nearly $1 billion into developing Spacelab over the past 10 years. Its first voyage has been put off several times, largely because of technical hitches with the US shuttle, in which the lab is to ride piggyback like a camper in a pickup truck. When Spacelab does finally go up, the shuttle will carry six astronauts, including the first European (West German) members of a US space team and the first two researchers.
As this is being written, NASA officials are still hoping for a late November launch. But they've also given thought to pushing the flight back to February, the only other available ''window'' for a launch. Celestial conditions would be better suited to the experiments then. NASA faces a crowded launch calendar, however, and delays are costly. ESA officials estimate the postponement is costing $300,000 a month, the price of keeping ready the teams that supervise the experiments.
Still, scientists in both the European and US space communities contend none of this has frayed relations. ''We all realize this is a high-risk business, and these are the kinds of things that are going to happen,'' says Wilfrid Mellors, head of ESA's Washington office.
Experiments aboard Spacelab will be carried out in five categories. The areas reflect what scientists see as the two chief advantages of operating a laboratory in space over one on earth: nearly gravity-free conditions and an orbital-eye view of both inner and outer space.
A late liftoff will affect experiments in three areas:
* Astronomy and solar physics. Six telescopes will be used to scan space. One will study distant emissions that point to cosmic ''black holes.'' Another will try to deepen astronomers' understanding of the sun. Most have to be done in darkness. During the final 21/2 days of the mission, the shuttle will be in constant daylight, so the astronomy experiments are being bunched early in the flight.
* Atmospheric physics and earth observation. One experiment in this area, for instance, will involve snapping detailed photographs of the earth. Further mapping will be carried out on subsequent Spacelab flights, ultimately resulting in a complete charting of the earth's surface. About one-third of the globe has been mapped in detail so far. November's heavier cloud cover and the orientation of the sun nearer the horizon are expected to lessen the quality of the pictures taken. Mission specialists have decided to use high-speed black-and-white film instead of color, as originally planned.
* Space plasma physics. Tests here include studies of the earth's magnetic field and cosmic rays - some of which will be affected by the amount of light available.
Experiments in the two remaining areas won't be hindered by the delay.
* Materials processing. More than half the experiments will be in this field and will build on earlier shuttle flight work. The advantage of working with materials in space is that purity can be improved in a near-zero gravity. Drugs or metal alloys, for instance, can be mixed more effectively. Formation of crystals, via processes that one day might be used to make semiconductors, is enhanced.
* The life sciences. Spacelab researchers will be studying how people and plants react to being in space. NASA scientists need more information on this subject in order to put people in space for prolonged periods.
How well Spacelab's maiden mission goes will be important for more than scientific reasons, though. Its performance could have a bearing on NASA's hopes for a permanent manned station in space. A bravura debut for Spacelab might soften reluctance in Congress to provide the estimated $10 billion needed for such a station, which NASA argues is vital to future scientific and industrial exploitation of space.
In any event, Spacelab will offer both Europe and the United States a glimpse of how utilitarian a space laboratory can be.