Japan is about to roll out the Lexus of space station labs, a whopper in size and sophistication.

The $1 billion Kibo lab — which means "hope" in Japanese — is poised for a Saturday launch aboard space shuttle Discovery.

It will be the biggest and, by far, the most elaborate room at the international space station — a 37-foot-long scientific workshop as large as a school bus, with its own hatch to the outside for experiments and a pair of robot arms.

Making it even bigger will be a closet and porch.

Kibo is so enormous that three shuttle flights were needed to get it all up.

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Seven astronauts, one of them Japanese, will deliver the actual lab on the upcoming mission, along with the larger of the two robot arms.

A separate storage room loaded with Kibo equipment went up in March. The porch for outdoor science experiments and the smaller robot arm will fly next year.

Kibo (pronounced KEE'-boh) dwarfs the two labs already in orbit — NASA's modest-size Destiny and the even smaller European Space Agency's Columbus.

"It's usually the other way around, isn't it? Japanese products should be smaller, but this time it's the other way around," Japanese astronaut Akihiko Hoshide said with a chuckle.

Two decades in the making, the 16-ton Kibo is 9 feet longer than the U.S. Destiny lab, which was launched in 2001, and more than 14 feet longer than Europe's Columbus, which flew to the space station in February.

Shuttle commander Mark Kelly calls it "the Lexus of the space station modules."

"It's big and it's capable. I mean, it's got its own dedicated robotic arm. It's got its own air lock. Eventually, it's going to have an external platform for experiments. It's got a lot of capable science racks that are going in. So yeah, I think it's pretty impressive."

Kelly and his crew will install Kibo during the 14-day shuttle flight, then attach the Japanese storage compartment that was left in a temporary parking position in March.

Three spacewalks are planned to hook up Kibo and handle other space station work, like replacing an empty nitrogen gas tank and seeing how best to clean a jammed solar-wing rotary joint.

Bill Gerstenmaier, NASA's space operations chief, said it seems like simple tasks.

"But when you get into the details of what's actually involved ... it's an extremely complicated mission," he said.

Besides all that work, one of the Discovery astronauts, Gregory Chamitoff, will swap places with the space station's current U.S. resident, Garrett Reisman, who will return to Earth on the shuttle following a three-month stay. Chamitoff will spend six months up there.

Just last week, NASA decided to proceed with its shuttle mission as planned, even as the Russians continue to investigate April's rocky landing by a Soyuz spacecraft carrying three astronauts home from the space station.

A Soyuz constantly is docked at the orbiting outpost for use as a lifeboat in an evacuation.

Discovery's flight will be a milestone for NASA in more than one way.

It will be the 10th shuttle mission since the 2003 Columbia tragedy and will leave just 10 more shuttle flights before the fleet is retired in 2010. That will mark the end of space station construction.

Discovery's fuel tank is the first to incorporate all the post-Columbia changes from the start of construction instead of later in the construction phase.

While shuttle managers expect this fuel tank to be the best one yet — i.e., with minimal insulating-foam loss — a full inspection of the spaceship's thermal skin still will be required.

That inspection will occur much later in the flight than usual. That's because Kelly and his crew won't get their inspection boom until they arrive at the space station.

The 50-foot laser-tipped pole was left there in March by the previous shuttle visitors; it couldn't fit in Discovery's payload bay given the size of Kibo.

Another milestone for Discovery's upcoming mission: Astronaut Karen Nyberg, the lone woman on the crew, will become the 50th woman to fly in space.

She will be rocketing into orbit just a few weeks before the 45th anniversary of the first woman in space, Soviet cosmonaut Valentina Tereshkova, and the 25th anniversary of the first American woman in space, Sally Ride.

"What I'm really looking forward to is the time when we're not counting anymore," Nyberg said.