The International Space Station

The first piece of the International Space Station definitely won't be launched as scheduled this June. By now, Space Shuttle flights have become so routine that they rarely make headlines. But when the shuttle Endeavor blasts into orbit in July, people all over the world will be watching, because Endeavor will be carrying two American construction workers into space. Equipped with the spacegoing equivalent of hard hats, cordless drills, and lunch boxes, astronauts Jim Newman and Jerry Ross will bolt together the first two pieces of the International Space Station. By the time the station is completed, around the end of 2003, it will be the size of a city block and one of the brightest objects in the night sky. Like the building of the pyramids, construction of the station will require years of heavy-lifting and thousands of laborers. The work, shared by 16 nations, will be dangerous and expensive. But it will also be a grand adventure, one that is just as likely to produce unanticipated discoveries as it is to encounter unexpected challenges. To give you an advance look at what will be the largest peacetime engineering project in history, we devote this section to the International Space Station.
What are we doing about the Service Module being schedule?

The Russian Service Module is arguably the most critical element of the entire International Space Station. The third piece to be launched, the Service Module will provide life support and critical controls for the first crews living aboard the station. But construction of the module is already more than two months behind schedule, leaving some people wondering whether the Russians will be able to deliver the promised hardware in time for its late 1998 or early 1999 launch. Fortunately, NASA has a backup plan. The space agency has contracted with the Navy to develop an Interim Control Module that could take the place of the Service Module in orbit. While the ICM wouldn't provide living quarters for astronauts, it would enable construction of the space station to go forward as planned. To build the ICM, the Navy is modifying a "secret" spacecraft that was headed for the junk heap. It's a pre-Challenger relic that was actually never much of a secret. "It was a spinning upper stage to boost shuttle-launched Navy satellites into higher orbits," says the Naval Research Laboratory's Ed Senasack, who helped engineer the modifications that will turn the propulsion vehicle into an element of the space station. The ICM can provide attitude guidance and control, and reboost the station if the Russians fail to deliver the Service Module originally designed for those duties. Though smaller than the Service Module, the Navy module has more than enough rocket power to do the job. The squat module will ride into space inside a cylindrical container; it will then be extracted and deployed by shuttle astronauts. Arms tipped with 5-pound thrusters swing out and away from the main ICM body. Along with a primary rocket rated at 110 pounds, the thrusters can be used to move the space station to a higher orbit. It's a delicate process during which the engine is fired in short bursts. "You want to be real gentle because of the station's size and various arrays [of solar panels and radiators]," says Naval Research Laboratory engineer Alan Jacoby. Spherical propellant tanks carry about 12,000 pounds of fuel, enough for at least a year of space station operations. Valves, connectors, and other components that are being added to the ICM will allow its tanks to be refilled in orbit. Even if the Russians deliver the Service Module on time, NASA isn't willing to put the ICM back into mothballs. It almost certainly will be brought into orbit and used as an auxiliary propulsion unit or as a backup to the Service Module. Or it could be used for something else. "It's a pretty capable bus," Senasack says. "It could even be used to reboost the Hubble Space Telescope."
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