Soviet plans for a large orbital station have been clouded by guidance trouble with Moscow's present transport capsule. So have the prospects for an eventual space shuttle, which a recent official booklet had hinted at.
The premature but safe landing April 22 of a Soyuz-T capsule has delayed what would have been the first manned trip to a prototype for the envisaged orbital complex.
The mission was aborted before the three-man crew could dock. ''Because of failures in one of the systems, the craft was unable to get onto the calculated approach regime,'' a Soviet newspaper said. It gave no further details.
Beyond presumed embarrassment at the failure - the linkup had been timed to coincide with the anniversary of Lenin's birth - Western experts can only guess at the long-term effect of the hitch.
They assume Moscow remains determined to press ahead with plans for an orbital complex, and that another manned flight to the Salyut-7 prototype is only a matter of time. But if and when Moscow moves toward launching a reusable shuttle, the guidance problem would take on far greater relevance, the analysts say.
A permanently manned space complex would, like the United States' space shuttle, have clear military potential. But Moscow holds that, unlike the ''militaristic US shuttle,'' the Soviet program is ''peaceful.''
Soviet guidance problems are not new.
One reason cited by Moscow for the introduction, in late 1979, of the Soyuz-T manned capsule is its improvement on the previous Soyuz's guidance system. Among other changes, Moscow added an on-board computer, hiking maneuverability.
There have been roughly 50 Soyuz flights in all. Four of those since the late 1960s have returned before docking, though it is unclear exactly how many of these instances involved guidance snags.
Last year a Soyuz-T flight, which was a joint Soviet-French mission, briefly ran into guidance trouble: The craft tumbled wildly as docking with Salyut-7 neared.
In Paris after the otherwise smooth mission, French astronaut Jean-Loup Chretien said that as the Soyuz-T sped toward rendezvous, ''The computer on board stopped doing automatic piloting.'' He said this was because it ''left the field'' - a pilot's term, he said, stopping short of suggesting total ''breakdown.''
''The vessel was no longer oriented toward the station. . . . We could no longer see the station.
''There was rotation on three axes . . . due to instructions of the onboard computer to go back to the original position. Since it was at that moment the computer broke down, the vessel was in rotation around its three axes and was thus like a stone rolling over.''
He said ''appropriate maneuvers were (then) made by the three crew members, meaning that manual approach was accomplished in the ensuing minutes.''
The latest Soyuz-T hitch follows expansion of Salyut-7 as a move toward creating an eventual orbiting complex. The Soviet plan is to assemble such a complex by ''module'' - around the cylindrical Salyut-7 launched a year ago.
The first major move in this direction came in 1981, when Moscow docked a ''prototype module'' with Salyut-7's similar, but nearly spent, predecessor, Salyut-6, and experimented with maneuvering the structure. Salyut-7 included an improved docking mechanism to accommodate such modules.
On March 2 of this year Moscow launched a second experimental module, docked it to Salyut-7, and then dispatched the Soyuz-T trio for rendezvous.
All went well until then, Soviet reports suggest. The module had ferried nearly four tons of cargo, including ''life-support'' material. The plan was for the Soyuz crew to unload this. The module would then ''be used for work and rest by the cosmonauts'' on their expanded station. Press reports did not specify whether the complex would be expanded further by adding another module.
The US, too, has entertained long-term ideas of assembling a large orbital complex. The US shuttle could theoretically ease stocking, or even assembly, of such a structure.
Moscow has so far sought an orbital complex via launch of modules and manned capsules atop less versatile, and ultimately more costly, one-shot rockets. Moscow has also built a commanding lead in keeping men aloft for long periods of time.
Soviet officials have repeatedly said, meanwhile, that so far they have no interest in developing a reusable shuttle.
But a booklet recently distributed here by the Soviet Novosti news agency takes a different tack on the shuttle. Terming current Soviet ''experiments in orbital stations'' a step toward ''giant space complexes of the future,'' the booklet adds: ''Special importance will be attached to developing new facilities for taking cosmonauts and cargo into space orbits and bringing them back to earth. These will possibly be reusable space vehicles that will deliver crews and cargo to orbital stations and bring them back to earth.''