After being rushed in from Russia, a toilet pump was loaded into space shuttle Discovery on Thursday just in time for this weekend's liftoff to the international space station, where the lone commode is acting up.

A NASA employee based in Moscow hand-carried the pump on a commercial flight that touched down Wednesday night. Within hours, the pump and related equipment were packed away aboard Discovery.

Discovery is scheduled to blast off Saturday on a 14-day mission. The main delivery item is a 37-foot-long Japanese lab; it will be the biggest room once installed at the space station.

Good weather was forecast for the late afternoon launch, and the countdown was going well.

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While the three space station residents are eager to see the Kibo lab, the bathroom situation has become a more pressing issue.

For the past week, the two Russian and one American men have had to periodically manually flush the urine side of the Russian-built toilet. The job takes 10 minutes and requires two people.

"Insert that into your daily life and you can see it would be quite inconvenient," Kirk Shireman, NASA's deputy space station program manager, said at a news conference.

The solid-waste part of the toilet is working properly.

The American on board, Garrett Reisman, will return to Earth aboard Discovery after a three-month stay. His replacement, Gregory Chamitoff, will have to deal with any lingering bathroom problems.

NASA plans to launch another Russian toilet aboard a space shuttle later this year, along with other equipment that will enable the space station crew size to double.