Science / Medicine : Shuttle Versus Shuttle : The recent launch of a Soviet space shuttle shows two things: the Soviet Union remains strongly committed to a broad range of goals in space exploration, and the Soviets have benefited profoundly from U.S. research efforts.

The recent launch of the Soviet space shuttle--a vehicle that is both remarkably similar and yet significantly different from its U.S. counterpart--telegraphed to the world that the Soviet Union remains strongly committed to a broad range of goals in space exploration and has benefited profoundly from U.S. research.

Furthermore, many experts in the United States believe the successful launch of the shuttle Buran on a fully automated, unmanned test flight means that the Soviets have moved ahead of the United States in a number of key areas in space science, and they clearly intend to stay there. Several other orbiters are under construction in the Soviet Union, and the reusable vehicles are expected to be the major source of access to a huge, new space station that the Soviets are planning for the mid-1990s.

“It’s just one more example of their continuing commitment across the board to space,” said John M. Logsdon, director of the Space Policy Institute at George Washington University and an expert on the Soviet space program.

Many experts were clearly surprised by the level of technological achievement that the flight of the Buran demonstrated, especially in computer sciences, a discipline in which the Soviets had been woefully inadequate. Any space shuttle--whether ours or theirs--is flown almost entirely by computers because the level of control needed to maintain the vehicle is far beyond the ability of even the finest pilots. Thus the successful flight of the Buran proved that the Soviets have made great strides in the development of computers, and they have brought off a major technological achievement.

“This is the biggest thing they’ve bitten off since Sputnik,” said John Pike, space policy expert with the Federation of American Scientists.

But beyond that, the Soviets scored a coup in the design of their craft that many American scientists envy.

Unlike its American counterpart, the Soviet shuttle has small engines used only for maneuvering the vehicle in space and slowing it down for reentry. Its main engines are in the liquid-fueled Energia rocket strapped to its side, a powerhouse that rivals those built by the United States to send astronauts to the moon.

Conversely, the main engines in the U.S. shuttle are in the orbiter itself, and the United States no longer has rockets in the same league as the Energia.

What that means is that the Energia can be used for a wide range of projects independent of the Soviet shuttle, and that gives the Soviets a powerful, versatile vehicle capable of carrying enormous payloads into space in a wide range of configurations. It could be used, for example, to send an entire fleet of robotic vehicles to explore the other planets in a single launch.

Since the Soviet shuttle itself is not an indispensable part of the propulsion system, other payloads can simply be strapped to the Energia in place of the shuttle, as was done in the Energia’s initial test flight a year ago. That would permit the Soviets to launch more than 200,000 pounds into space. The U.S. shuttle, by contrast, can carry less than 60,000 pounds.

“What puts the Soviets definitely ahead is they have a multipurpose heavy lifter,” said Robert L. Staehle, president of the World Space Foundation. “That’s going to give them considerably more flexibility.” The nonprofit research foundation is based in South Pasadena. In the United States, Staehle noted, “We’re just starting to think about that.” A heavy launch vehicle is not expected to be available in this country until the latter part of the century, at the earliest.

Despite that great difference between the Soviet and the U.S. shuttles, the vehicles are more similar than different. Few doubt that the Soviets profited from U.S. research. The shuttle has been the keystone of the U.S. space program for a decade, and the National Aeronautics and Space Administration and individual scientists and engineers have made their research available to just about anyone who has asked. Indeed, detailed drawings of nearly every part of the U.S. shuttle can be purchased at the gift shop at the Johnson Space Center in Houston, offering keen insights into the shuttle’s design.

That may explain why both vehicles are covered with heat-resistant thermal tiles, both have Delta wings and both are about the same size. Even the paint is nearly identical. But there are subtle differences. The Soviet shuttle is about three feet shorter and a little wider, and the crew compartments are slightly different.

But the similarities are not an accident.

“Ten years ago the shuttle was barely within our grasp, and clearly beyond the Soviets’ grasp,” said Pike of the Federation of American Scientists.

“There’s no doubt the Soviets have a big ‘vacuum cleaner’ ” to gather U.S. research, Pike added. “But at the end of the day, they had to build it themselves.”

Some experts believe the Soviet decision to test-fly the craft without risking human lives says much about the level of caution in the Soviet program.

“It means they were not very sure it would work,” Logsdon said. “It was a very peculiar decision. They decided not to risk a crew.”

But in fact there was no need to risk human lives, as the Soviets demonstrated.

U.S. shuttles are not designed to land automatically, partly in deference to pilot-astronauts who want to feel they are in control during the final stages of the flight. However, far more critical maneuvers occur long before touchdown, and those are all controlled entirely by computers that take over essential operations 30 seconds before liftoff.

It would not be possible, for example, for a pilot to guide a shuttle throughout the hourlong descent from orbit. The level of control is so exacting, according to space engineers, that if the attitude of the craft is off ever so slightly it would heat up almost instantly to the point that it would incinerate as it re-enters the Earth’s atmosphere.

So automation is a major part of every space flight.

“The bottom line is clearly it’s nice to have a pilot there to intervene if anything goes wrong, but these things are too complicated for a pilot,” Pike said. “All the pilot is doing is just looking at the screen.”

Even during landing, Pike said, “he’s just fooling with the control stick, doing what the computer is telling him to do.”

So the fact that the first Soviet flight was fully automated is of little significance, because no pilot could have done it anyway without the right computers. It does, however, prove that the Soviets had the right computers.

But one flight does not make a successful shuttle program, and experts believe it will be years before the Soviets feel comfortable.

“It’s going to take them a long time to get to the point that they have operational confidence in their shuttle,” Pike said.

There need be no rush, however, because the Soviet shuttle program is part of a much bigger package and is not expected to play a significant role in the Soviet space program for several years.

“This (the shuttle) is part of a 30-year systematic process,” Logsdon said.

The centerpiece of the Soviet program is and will continue to be a permanent presence in space. The Soviets broke their own record for space endurance when cosmonauts Vladimir Titov and Musa Manarov passed the 326-day record July 12 aboard the Mir. They are to remain in orbit until sometime after Dec. 21, when they will have completed more than a year in space. The only way for a U.S. astronaut to get to space is aboard the shuttle, and shuttle missions are limited to a week to 10 days.

By the mid-1990s, the Soviets hope to have a 20-man space station in orbit, and the purpose of the Soviet shuttle fleet will be to supply that station, Logsdon said.

That third-generation space station is expected to be the major staging arena for Soviet missions to Mars and the moon.

The United States also expects to have a space station in operation sometime in the late 1990s, and American experts believe it will be far more sophisticated than the Soviet facilities. But the cost of the U.S. station has climbed to more than $30 billion, and it is not certain that it will be funded.

The Soviets, too, have blinked somewhat in the face of the high cost of space exploration.

According to Aviation Week and Space Technology, a respected trade journal, the Soviets spent more than $10 billion on the development of their shuttle, and that is a hefty price. That has led, in turn to outspoken criticism in the Soviet Union over the wisdom of following the United States down the shuttle course.

Roald Z. Sagdeev, until recently the director of Moscow’s Space Research Institute and a longtime confidant of Soviet leader Mikhail S. Gorbachev, has bitterly and openly opposed the shuttle.

While hailing the flight of the Buran as a technological achievement, Sagdeev recently told the Associated Press that the flight “had absolutely no scientific value.”

“My personal view is that American experience with the shuttle indicates that from the point of view of cost efficiency, the shuttle is in deep trouble,” Sagdeev said.

Sagdeev has been outspoken in the past, reflecting what many Westerners believe to be a deep split within the Soviet scientific community over the direction their program is taking. He is in charge of an ambitious Soviet program to send an unmanned, automated rover to Mars in 1994, and possibly return samples to Earth, and he is a strong believer in using satellites--not people--to explore the solar system.

That gives the Soviets one more thing in common with their American colleagues: A lot of scientists in this country also think the U.S. shuttle is a waste of money.

SHUTTLE DIFFERENCES

Soviet and U.S. space shuttles are very similar in design, but there is one important difference. The swelling in the tail section of the U.S. shuttle (1) is called the “OMS pod” for Orbiter Maneuvering System. The shuttle’s three main engines, which draw their fuel from the huge external tank on which the shuttle is mounted, are inside that pod. The four main engines for the Soviet shuttle, however, are in the tail of the Energia rocket instead of in the shuttle itself, so it has a slimmer tail section. The U.S. shuttle uses two solid rocket boosters (2) attached to the external tank, and the Soviet shuttle uses four. The windows (3) in the cockpits are placed in exactly the same location, although the internal cockpit configuration differs slightly. Both shuttles use the double delta wing (4). The body (5) of the Soviet shuttle is about four feet shorter than the U.S. shuttle, and slightly fatter.