The International Space Station (ISS)

The history of what is now called the ISS started during the Reagan administration. Reagan proposed that the US take the lead in a project to construct an Earth-orbiting laboratory. The first incarnation was called "Space Station Freedom"

This was to be an international project, with allies of the US participating at a high level. NASA proposed to build SSF for $9 billion. Soon, however, the project was suffering from cost overruns. At nearly the same time, the scientific community weighed-in with its ambivalent attitude-SSF was in trouble (additional administration documents from Bush's presidency: #1, #2).

By 1990 escalating costs had started to seriously erode support for the SSF in Congress. A new factor, however, arrived in time to revive support for the project: due to the economic recession, support from several politically powerful states that needed its jobs helped bolster the project.

As the economy revived, support again waned. The newly elected Clinton administration proposed to dramatically scale back the project (it was on its 7^th redesign!). But now, an international crisis arose: the collapse of the Russian economy.

With the US afraid that the Russians would sell-off sensitive military technology and know-how, the Clinton administration sought a way to keep their scientists employed. One way was to pay Russia to launch US satellites. Their technology was reliable, and cheaper than the US alternatives.

After discussion of this initiative, the Russians made a counter proposal: that they join the US in the space station program. The last element was in place to save the space station: keeping the Russian scientists and engineers employed on a civilian project.

After some back and forth, the final agreement for Russia to participate as a full partner was signed in August of 1993. This agreement appealed to both sides for a number of reasons. For the US it meant 1) a way to use Russian experience in space-station design, 2) a way to dramatically reduce the costs of the endeavor, and 3) a way to keep the Russian aerospace industry working on a civilian enterprise. Hopefully, this would also help stabilize the Russian economy.

For Russia, it was a way to get a badly needed infusion of hard currency, and to keep their aerospace industry alive (so that they could keep their defense industry healthy).

The International Space Station now had a political motivation beyond the initial technological/scientific mission it had been founded on. Its future is now brighter.

The design of the ISS owes much to the Russian experience with Mir. It will be composed of a number of interlocking modules.

The first component for the ISS, Zarya ("Peace"), was successfully put into orbit using a Russian Proton booster on November 20, 1998. Zarya is the control module, and is designed in similar fashion to the main Mir module. The Zarya is also known as the Functional Cargo Block ("FGB").

Zarya is 41 ft long, and 13.5 ft in diameter, and has a mass of 20,000 kg. It has a large pair of solar power arrays that generate 3 kw of electricity. The Zarya is equipped with its own propulsion system and had 16 tanks to store six tons of propellant. It is equipped with 24 large steering jets, and 12 smaller jets for in-orbit maneuverability. Two large engines allow it to make larger orbital maneuvers (e.g., reboosts).

Much of the function of Zarya will become redundant once the larger, and more sophisticated Russian-built "Service Module" is finally completed and mated to Zarya. But at present it supplies the power, orientation control, and communications system for the US-build "Unity" module.

A few weeks later, Dec. 4, 1998, the Endeavour rendezvoused with the Zarya and mated the Unity module. The Unity is the first "Node" to be installed. Its main use is to provide a passageway to the US laboratory module, habitation module (living quarters), and provide an airlock. The Unity has six hatches to allow it to use "Pressurized Mating Adapters" to connect it to other modules as well as for Space Shuttle docking hardware.

Until the Service Module (or "Zvezda") is attached, however, there are no living quarters presently in orbit. The Service Module is 43 ft long and weighs 42,000 lbs. Its guidance and propulsion systems will take over all control from Zarya. It will house a crew of three.

The "Zvezda" will have four docking ports, one for the Proton resupply vessel, one for a Soyuz docking port, one for the Russian science power platform, and one "Universal Docking Module". The Zvezda will have three compartments, two small ones, adjoining the larger "Work Compartment", will serve for crew transfer facilities.

The Work Compartment will house a lab, three sleeping quarters, a bathroom, and exercise facilities. All of the usual facilities are also integrated into this module: communication equipment, life support, data processing systems, flight control, and propulsion systems (including propellant tanks).

The launch date for Zvezda has slipped from October to the window of 12/26/99 to 1/16/00. Once it is successfully in orbit, and fully functioning, it will be manned by a three-person crew sometime in the Spring of 2000.

About one month later, the US "Spacehab cargo module" will be put in place during a Shuttle flight (supplies for future installations). A month later the first "Integrated truss structure" ("Z1") will be installed. The truss will supply mechanical support for the eventual attachment of the large solar arrays that will supply most of the electrical power.

Several months later the US "Laboratory Module" will be added. This is the main US facility housing both the experiments (biomedicine, biotechnology, materials and fluid sciences, combustion research, space and earth science, and engineering) as well as the experimentors. The lab is 28 ft long, and about 12 ft in diameter.

Eventually, there will be six laboratories, two American, one European ("Columbus" #1, #2), one Japanese (JEM & "Kibo"), and two Russian modules. The Canadians will contribute a robot mechanical manipulating arm. The Japanese module will have a space exposure capability. The last installment will be the US "TransHab" facility that will provide a very large, but low-weight living quarters. It will be constructed of Kevlar and inflated like a balloon.