Soviet shuttle ready. US experts predict launch at any time, but are puzzled over spacecraft's purpose

Scoot over, NASA. The Soviets are about to attempt a space shuttle feat of their own. The official Soviet news agency, Tass, said on Sunday that the Buran, or Snowstorm, is undergoing final preparations for blastoff. Although Tass did not specify a launch date, the timing of such announcements in the past seems to indicate the unmanned flight will occur within one or two weeks, if not sooner.

The Soviet bird is a look-alike for the United States shuttle. It wears the same triangular wings and ceramic-tiled underbelly, and it carries roughly the same weight into orbit - 60,000 pounds.

The most obvious difference is that the main engines for the Soviet shuttle are on the Energia, a heavy-lift rocket that will be used to boost the orbiter into space. Main engines for the US shuttle are on the orbiter's tail.

Because the Energia can be used to launch payloads into space without the shuttle orbiter, the Soviets will have a more versatile system, says Marcia Smith, head of Soviet space analysis at the Congressional Research Service.

Politically, the two shuttle programs may be more alike than not. Like the US effort, the Soviet program has supporters and detractors.

``This program appears to have come out of their aviation industry and not out of their space industry,'' says James Oberg, space engineer and author. ``Their space industry has been hostile'' to it, he says.

Whether or not the purpose of the program has been spelled out within the Soviet government, it has US experts scratching their heads.

``It is hard to say how the shuttle will impact their space program at all,'' Ms. Smith says. ``The specific need that they have identified publicly is not to take things into orbit but to bring things back.''

The Soviets will need this return-to-earth capability when they begin to send specialty modules to their Mir space station.

Mr. Oberg estimates the Soviet program has cost close to $20 billion. The shuttle will be launched only once or twice a year, because that is how often it will probably be needed to take up or return the delicate payloads that it is suited for. At that rate, Oberg says, ``the cost-benefit ratio certainly is questionable.''

``The kind of thing [Mikhail] Gorbachev needs out of the space program in the next five years is not represented by a $20 billion-a-year NASA copy,'' he says.

``This program was initiated under [President Leonid] Brezhnev, who was not known for good judgment,'' Oberg says. ``It was brought to you by the same people who brought you Afghanistan.''

The Defense Intelligence Agency reportedly believes the Soviet shuttle may be used for launching ``space mines'' that damage missile-warning and communications spacecraft.

Oberg calls these ``desperation guesses.'' The Soviets have easier ways than the shuttle for launching such material, he says. And payloads for their planned new space station can go up in the heavy-lift Energia rocket.

There is one rationale for the Soviet shuttle that US experts agree on: keeping up with the Joneses. The Americans, after all, have a few in the garage.

But just like American and Soviet automobiles, the shuttle designs do have differences.

In addition to the main engines on the Energia, the Soviet shuttle system uses four liquid rocket boosters for liftoff. Oberg counts 20 Soviet engines for liftoff. The US shuttle uses three main engines and two solid rocket boosters.

``If they think that is simpler, they are welcome to try to fly it a few times,'' he says.

Speculation that the Soviet shuttle would have jet engines for landing seems to have been laid to rest. Engines were used for takeoff and landing on earlier test flights but are not feasible for spaceflight, Oberg says. The Soviet orbiter will glide to Earth, baring its heat-resistant underside to the atmosphere just as the US shuttle does.

The Soviet shuttle design ``shows copy and not convergent evolution,'' Oberg says.

But John Pike of the Federation of American Scientists says that ``the Soviets obviously didn't just steal our plans.''

Because the Soviet orbiter doesn't carry the main engines and leans into the wind during liftoff, US engineers say the vehicle must be built to handle more stresses than the US version. This means it is heavier, the center of gravity changes, and different technical challenges have to be overcome.

If this and future flights succeed, the Soviets will have shown an increased prowess in space exloration.

But if it fails, ``I don't think we are looking at a two-year delay,'' Oberg says. ``They might just put the whole thing in a museum next to the T-144 [Soviet supersonic transport].''