Saturday's shuttle mission to the International Space Station can come none too soon for station crew members. A broken toilet has had them using a backup system, and they need a new pump mechanism. The crew of the shuttle Discovery is bringing them one, as well as the largest component of Japan's contribution to the space station, a science laboratory called Kibo, meaning "hope." VOA's Paul Sisco has more on NASA's 26th mission to the International Space Station.

Discovery is counting down and the weather is cooperating for Saturday's planned shuttle launch from the NASA space center in Florida.

Shuttle commander Michael Kelly and his crew are ready to go. "My crew is ready. We have been training for a year and we are really looking forward to our launch," Kelly said.

A special Russian-built pump was delivered to Discovery's cargo hold at the last minute. It will replace the malfunctioning mechanism in the space station's toilet, which has been broken for more than a week.

However, Discovery's primary cargo is an 11-meter long Japanese module. It is the largest of three components of a space laboratory called Kibo.

"It's going to be used for fundamental chemistry, fluid physics, regular physics biology experiments," Kelly said. "Some of those will come up at a later time, but it is going to be a world class laboratory."

The first section of the Kibo lab was delivered to the space station last March. This mission will deliver the 14,515 kilogram main pressurized module and a robotic arm that will be attached to it.

Mission specialist Karen Nyberg operates three robotic arms, and with Japanese colleague Akihiko Hoshide, will maneuver the lab modules into place.

Nyberg explains the mission. "He and I are going to be the prime crew members to get the Japanese module installed and up and running," Nyberg said.

Astronaut Ron Garan says three space walks are planned, each expected to last over six hours. In addition to hooking up Kibo, the space walkers will work to free a jammed solar wing on the station and Garan will swing around on the end of a fully extended robotic arm to stow away a spent nitrogen tank.

"Looking straight down on the aft side of the station and ... [with] the earth 250 miles below, it will be a pretty spectacular ride," Garan said.

Discovery is scheduled to return to Earth Saturday June 14.

NASA has 10 more shuttle missions planned to complete construction of the space station by 2010. That is when the space shuttle fleet is slated for retirement.