While the US space shuttle -- and with it the US space program -- has been chugging and stalling through its pre-launch tests, the Soviet Union has gained steadily on the large lead the United States built from astronautical successes of the 1960s and early 1970s.
Aerospace observers say the new Soviet spacecraft, Soyuz T, underwent extensive design changes in 1979. It now has propulsion and navigability which enable it to perform complex rendezvous and docking maneuvers with the Salyut 6 space station. The Soyuz T uses onboard computers, microelectronics, and solar panels -- all new to the Soviets.
The Soviet space program also has demonstrated the ability to refuel and resupply a space station using unmanned tanker rockets -- something the United States has not done.
"It is very clear that they [the Soviets] are gung-ho on space," says Jesco Von Puttkamer, a National Aeronautics and Space Administration (NASA) planner. "They certainly will not surpass us overnight with their limited hardware, but they do have a very strong, continuing program."
But the gap Moscow is attempting to close is large. Prior to its updating this year, for example, the Soyuz was considered by many aerospace engineers to be little more than an oversized satellite, in many ways below the technical level of the US Mercury spacecraft flown 18 years ago.
Soviet proficiency in rocketry still is not believed to match that of the US. During 1978 and 1979 tests of a giant Soviet booster -- comparable to the Saturn 5, which carried American astronauts to the moon -- failed three times, according to Congressional Research Service (CSR) records. Because of these failures, the size of the payload the Soviet Union can put into orbit still is limited.
But one way around the weight limitation is to use Soyuz as a kind of shuttle craft, with sleeping and storage aboard Salyut. Using this procedure, cosmonauts were able to log 175 days in orbit last year.
The cosmonauts conducted zero-gravity industrial experiments using a small furnace and other tools. An analysis by the CRS indicates the Soviets emphasize technological and medical research in near-earth orbit. Manned exploration of the moon and planets is unlikely in the near future.
But, the CRS report says, "going to the moon with men has been talked about so long and prepared for at such expense by the Russians that one must assume they will proceed as soon as they solve their present problems of unreliability of hardware. Our first clues may come from appropriate precursor flights" -- particularly, those of a giant booster rocket.
NASA's Von Puttkamer says he believes that the next step for the Soviet Union may be to dock another Salyut space station with the orbiting one, thereby doubling the work area. In this building-block fashion, a modest space station capable of accomodating six to eight cosmonauts may be constructed in orbit. But Mr. Von Puttkamer says this technique offers the Soviets only limited growth potential because the cosmonauts would not be particularly safe.
"Space stations make sense only with abort capability -- escape capsules or fire-proof shelters," Mr. Von Puttkamer says. "This is why we are developing the shuttle before developing a permanent space station."
The Soviet Union, the CRS says, has shown an equal awareness of the need for reusable space vehicles: "Considering the Soviet effort to maintain a position of leadership in space, and the continued high level of Soviet flight activity (triple that of the United States), they have even more compelling reasons to develop a reusable shuttle as a cost-saving device."
Several sources indicate the Soviets have been flight-testing a small, reusable space vehicle similar to the US M-2 which was scrubbed when the shuttle program began. A manned flight test of that vehicle in orbit has not yet been attempted.
In number of missions, the Soviet space effort is the most active in the world. Last year, the USSR sent 124 payloads into orbit; most of these were military satellites.The US orbited 18 objects and Japan sent up 2.