Russian engineers readying the Soyuz spacecraft slated to ferry the first long-term crew to the International Space Station (ISS) hit a small snag last week, but said that despite the glitch they are on schedule for the October 30 launch.

The Soyuz TM spacecraft will carry a U.S. astronaut and two Russian cosmonauts to the ISS for a four-month tour of duty. Until now, the fledgling space station has only been visited for short periods by assembly and outfitting crews.

The processing team at the Baikonur Cosmodrome planned to complete the electrical testing on the Soyuz last week, however, the engineers at the Russian launch site in Kazakhstan discovered a failure in one of the components in the flight-control system.

According to Yuri Grigoriev, the deputy designer general at RKK Energia, Soyuz's manufacturer, one of the communication channels in the transmitting device used during the spacecraft's reentry into Earth's atmosphere failed. The officials considered "cannibalizing" the same kind of device from a backup Soyuz vehicle. However, after an evaluation of the problem, they concluded that the failure is too minor to warrant a replacement.

Currently, two Soyuz spacecraft are in Baikonur to provide a backup capability for the high-profile ISS operations.

The engineers at Baikonur hope to move the Soyuz TM spacecraft to its fueling station between October 3 and October 6. The vehicle will be then cleared for mating with the three-stage rocket booster that will loft it into orbit.

The rollout of the entire Soyuz stack to the launch pad is expected two days before launch.

The commander of the first long-term crew to the ISS, astronaut Bill Shepherd and Russian cosmonauts, Yuri Gidzenko and Sergei Krikalev, will return to Earth aboard a space shuttle, while their Soyuz will remain docked to the ISS to serve as a lifeboat for the next expedition to the station delivered by the shuttle.

Approximately every six months, so-called "taxi" crews will travel to the station aboard a fresh Soyuz spacecraft. After a short stay on the ISS they will return home in the "old" vehicle. At least one Soyuz vehicle will be docked to the ISS while the people inhabit the station. Soyuz rotation is necessary to provide ISS crews with an escape vehicle should an emergency arise that requires station evacuation.

A "lifeboat" craft capable of transporting up to seven crew members to safety is currently being developed by NASA. Eventually, it will replace the three-person Soyuz and allow more crewmembers to stay in the ISS during future tours of duty.