"Ideally, that will give us a chance to catch our breath from the tremendous year that we've just executed in station assembly and more importantly it will give us an opportunity to focus on our early research program"

That year-long construction frenzy saw the installation of a massive truss, a U.S.-built lab module, a power tower and its soaring solar arrays, a robotic "Canadarm2" and the Quest airlock for spacewalks.

Commander Frank Culbertson, pilot Vladimir Dezhurov and flight engineer Mikhail Turin are set to ride with a four-man shuttle crew to the station aboard shuttle Discovery this week. Launch is set for 5:38 p.m. EDT (2138 GMT) Thursday from NASA's Kennedy Space Center.

Culbertson and crew will be the third to occupy the station since station partners established a permanent presence there in October 2000. The so-called Expedition Three crew will replace Expedition Two Commander Yuri Usachev and U.S. astronauts James Voss and Susan Helms, who have lived aboard the station since March.

The changing of the guard will happen on the fourth day of flight when the new and old crews swap customized seat liners within the Soyuz escape capsule docked to the station.

The Expedition Three mission itself officially begins when the hatches between the shuttle and station are closed the day that Discovery pulls away from the station. It is set to end in early December after shuttle Endeavour arrives to swap in the next long-term crew.

Comings and goings

Although no U.S. shuttles will arrive at the station during the upcoming four-month expedition, the demands on station hardware and support vehicles, crewmembers and ground support will be significant.

Expedition highlights include:

• Arrival of two Progress cargo ships with supplies. The first bug-shaped craft will arrive in late August carrying crew provisions, temperature sensors and a high-definition television camera. After the ship is unloaded, the crew will use it as a trash truck of sorts, filling it up with refuse and discarded equipment before sending it on a destructive plunge into the atmosphere. A second ship will arrive in mid-November carrying more provisions.

• Arrival of a Russian Docking Compartment in September. The crew will conduct three spacewalks to outfit the module, as well as to set up a Russian cargo boom and a commercial experiment. The final spacewalkers also will string cables for automated docking of spacecraft to the station.

• Arrival of a Soyuz taxi crew for an 8-day stay in mid-October. After more than two months in space, the Expedition Three crew will likely welcome a break from their routine with the arrival of two Russian cosmonauts and French cosmonaut Claudie André-Deshays, the only female space traveler certified to pilot the Soyuz capsule back to Earth.

• Installation of a new temporary sleep station. Culbertson and Turin will sleep in so-called kayudas, closet-sized rooms in the station's Russian crew quarters while Dezhurov will sleep in a make-shift sleep station in the Destiny lab module until the new sleep station is unpacked and put together.
• A short flight on a Soyuz capsule to move it from one docking site to another. Dezhurov will pilot the craft carrying Turin and Culbertson. The American likely will enjoy a rare opportunity to ride on the legendary vehicle.

The Docking Compartment will serve as an airlock doorway to space from the station's Russian-built modules -- Zarya, the initial building block, and the Zvezda Service Module that now serves as living quarters. The new module also will become an extra "parking space" where incoming Soyuz and Progress vehicles can dock.

The crew's first two weeks in space will be most intense as members huddle with the previous crew to hand-off duties and get up to speed on the station's most recent condition, help unload cargo from the shuttle during its nearly eight days docked at the station and start up new research experiments.

A long wait

Expedition Three was a long time coming for all three crewmembers -- the cosmonauts trained more than four years and Culbertson waited nearly eight years for this assignment following administrative stints, including oversight of a series of shuttle missions to the Mir space station. Seven U.S. astronauts carried out tours of duty on Mir as part of that ISS precursor project in the mid- to late-1990s.

"I'm very happy to be assigned to this particular crew and of course I'm very happy to be flying, which is the reason I came to NASA," Culbertson said. "Flying is what I really love and being in space is what I really love."

Dezhurov and Culbertson are space veterans, although Culbertson has never flown on a long-duration mission. His oversight of the shuttle-Mir missions will serve him well, he says. Turin, the rookie, is a long-time engineer with RSC Energia, the Russian engineering firm that oversaw the Mir space station and many other missions and spacecraft.

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