During the Apollo-Soyuz Test Project in 1975, two mission-control centers were operating at Johnson Space Center and in Moscow. Unlike the docking of Zvezda with the International Space Station, these two craft were docked manually. The three astronauts and two cosmonauts spent two days conducting joint experiments in orbit.

"Weve learned to work with our Russian colleagues, and they have a lot of experience," said Mark Ferring, lead ISS flight director. "Building that relationship has been a good thing."

Both control centers share responsibilities and operate the equipment that they launched into space.

Houston directs the general operation and Moscow controls the stations systems including guidance and life support once the service module docks in late July.

"In general we work as one big control center, but still have some autonomy in controlling our own equipment," Ferring said.

If the two space programs have one thing in common, it is detailed documentation of procedures -- from the mundane and routine to the life threatening. Both agencies wrote and agreed to use volumes of directions called "flight rules" that dictate how controllers operate and react to different situations aboard the station.

Ferring said controllers in both locations review the daily procedures, along with long-term plans stretching out several weeks or more. Controllers in each center can chat directly with each other in real time. Both agencies have also placed liaisons at the each others center for face-to-face contact.

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If a situation cant be resolved, it gets passed to mission managers in Moscow and Houston for a decision.

When the U.S. laboratory module docks with the ISS in January 2001, Houston assumes responsibility for station guidance and crew operation.

The gyroscopes aboard the lab module will provide attitude control supplied by the Russian service module to that point.

The Russian center will continue to work with Houston and monitor equipment. Much of the station events and construction will continue to occur over Russia to use ground-tracking stations positioned there.

When the first ISS crew occupies the station in November, both control centers will begin 24-hour operations in earnest.

"Theyre will always be someone to talk to," said Ferring of ISS crews who may need to make contact in the middle of the night.

Initially, the ISS control center will be staffed much like a shuttle mission, with a flight director, controllers, planners, public-affairs commentator and a capsule communicator to talk to the astronauts.

As the controllers and station crew become more comfortable with its operation, the ground-control staff may begin to scale back, particularly during sleep periods and free time, Ferring said.

Though the crew will be busy, it wont be the hectic pace shuttle crews endure on their roughly two week missions.

"On the shuttle, you have X number of days and youre coming back," Ferring said. "The station is more like working on your job. If you cant get something accomplished, you can reschedule tomorrow, or down the road."