An Orbital Workshop Greater Than the Sum of Its Parts

Like a family with a build-it-yourself furniture kit, astronauts and cosmonauts who will be assembling the international space station hope the parts fit together smoothly.

There's no guarantee. But the manufacturers in 16 countries on four continents who will supply those parts have promised to make every effort to see that the whole thing fits together. That's included in the agreements those 16 nations signed last January in Washington.

The trouble is there's no way to do a trial assembly on the ground of an ungainly structure that will eventually be large enough to cover a US football field. Besides, only a few of the parts will be available at a given time. It's little wonder that NASA administrator Daniel Goldin has called this "an unprecedented undertaking in international experimentation."

When complete, the station plus solar arrays will be 108.6 meters (356.4 feet) wide by 79.9 meters (290 feet) long. This 456,620 kilogram (1,006,664 pound) mass will travel 407 kilometers (253 miles) above Earth along an orbit inclined 51.6 degrees to the equator.

NASA had originally planned for an orbit inclined only 28 degrees. Planners switched to the higher inclination when Russia joined the project in 1993 so that spacecraft launched from Russia could reach the station. This greatly expands station access. Crews can travel on either a US shuttle or a Russian Soyuz. Cargo and fuel can arrive either by shuttle or by Russian robot Progress transports. The trade-off is that US shuttles can carry less cargo than originally planned because they need more fuel to reach the higher orbit.

It will take five years or more to build this orbital workshop, which will accommodate seven crew members at a time. The first unit is standing by at Russia's Baikonur space port in Kazakhstan. It's a US financed 21-ton pressurized unit built in Russia. Called the Functional Cargo Block, it provides energy, storage, propulsion, and docking points.

Shortly after Russia orbits it later this year, a space shuttle mission will attach a pressurized node called Unity that will add several docking ports to the cargo block. Then Russia is to launch its service module to provide the first living and working quarters for a small crew and thrusters to orient the nascent station.

With this much of the station in place, the first three-person crew will go into orbit and be ready to help in the ongoing assembly. The entire complex will eventually include six laboratories - two from the US, two from Russia, and one each from the European Space Agency and Japan.

Extensive solar arrays will supply electric power. There will be racks and platforms outside the pressurized modules to hold experiments exposed to space.

At this writing, the exact timetable for this construction is uncertain. Russia is behind schedule with its virtually complete service module. But NASA officials still expect that the agency's space station program manager Randy Brinkley is right when he says "the year of the international space station is 1998."