Members of the crew will be assigned to the station for lengthy tours. As the station is now designed, if something were to go seriously wrong, there would be no way for the crew to return to Earth unless a space shuttle just happened to be there. Normally, shuttles would visit the station only when delivering supplies or changing crews every month or so.
The prospect of American astronauts stranded in a disabled space station may not sit well with the nation as a result of the Challenger shuttle disaster, and astronauts are not too wild about the possibility of being stranded without an escape vehicle. Seven crew members died when the shuttle exploded shortly after launch last January.
"That's something we ought to have," Fullerton said bluntly. "There ought to be a way to get back to the ground."
A NASA spokesman said that although the escape vehicle is not included in the plan, it could be added later if deemed necessary.
"We didn't feel that was a decision that had to be made right now," spokesman Mark Hess said. One option being considered is to provide a self-supporting capsule near the station where astronauts could take refuge while waiting for a shuttle to get to them.
NASA sees the station as the obvious next step in manned exploration of space, giving the United States and its partners a permanent facility to carry out long-term experiments and begin manufacturing materials that can best be fabricated in a weightless environment.
Only the Soviet Union has anything like that, and only Soviet cosmonauts have been exposed to prolonged periods in space approaching those required for manned expeditions to other planets.
Although that would seem to place the Soviets far ahead in space exploration, the fact is that the Soviet Union and the United States chose different routes to reach similar milestones in space. In the late 1960s, both nations had come to the same fork in the road: Whether to next build a space station or a reusable launch vehicle.
The Soviets opted for a station, flew the first Salyut in 1971 and have had Salyut 7, a small station that is manned periodically, in orbit since April of 1982. Last February the Soviets launched Mir, the first element of a large modular station that is to be permanently manned. The United States chose to build a reusable space fleet first, and the Soviets are reported close to launching their first space shuttle.
The United States is now reaching toward a "permanent presence in space." The space station would be a massive facility, assembled in orbit by teams of astronauts who would be carried to their work stations by the shuttle. NASA estimates that it would take 32 shuttle flights to build and equip the station from 1993 through 1995. Seventeen flights would be needed just to assemble the main base, according to plans released last month by the space agency.
All shuttle flights have been postponed as a result of the Challenger accident, and will not resume before early 1988.
The station itself would consist of three laboratories--one Japanese, one European, and one American--plus crew quarters and support facilities. It would be manned at all times. The modules would be attached to a center boom, which would be part of an elaborate scaffolding that would support antennas, solar collectors and various experiments. In addition, there eventually would be several "free-flying" platforms to house "man-tended" operations so delicate that they would be harmed by activities causing minute vibrations and other disturbances aboard the manned facility.
The Europeans have also planned to supply a platform that would work with the station but would fly in a polar orbit as opposed to the station's equatorial orbit. The platform would cross the station's orbit twice daily and repeatedly pass over the entire surface of the Earth.
But the history of such European-U.S. space ventures has been checkered, at best. The United States and Europe had planned joint probes to Halley's comet, for example. But after the Europeans had already begun work on their spacecraft, NASA backed out, forcing the Europeans into a solo operation, which they carried out with great success when Giotto flew within a whisker of the nucleus of the comet last March.
Similar joint expeditions were planned to simultaneously study both poles of the sun, but again the United States backed out. The European probe, Ulysses, was to have been launched by the shuttle last May, but it is still on the ground in the aftermath of the Challenger disaster, and its launch is now several years away.
But nothing has rankled European space scientists more than the fate of the $1-billion Spacelab built by the Europeans for the space shuttle. The lab fits inside the shuttle's cargo bay, greatly expanding the scientific capabilities of the shuttle. It was to have been carried aloft many times as a major component of an international space program.
Flights Scaled Back