Japan's New Space Laboratory Opens Aboard Station
Japanese astronaut Akihiko Hoshide holds up a sign for the camera as he enters the Kibo lab for the first time.
Credit: NASA TV

This story was updated at 8:23 p.m. EDT.

HOUSTON — Astronauts christened the International Space Station?s (ISS) giant Japanese room with warm words and smiles Wednesday, officially opening the tour bus-sized Kibo science module aboard the orbiting laboratory.

Japanese astronaut Akihiko Hoshide opened the massive $1 billion Kibo laboratory at 5:05 p.m. EDT (2105 GMT) with a short speech before he and nine crewmates floated into its roomy interior a few minutes later.

?This is a great moment for the Japanese folks,? Hoshide said. ?One engineer down on Earth said it looks very empty, but it?s full of dreams, and I really think that?s what it is.?

Hoshide and NASA astronaut Karen Nyberg were the first to float into gleaming Kibo module. They wore face masks and goggles to protect against any loose debris that may have been floating around.

But caution soon gave way to orbital play as all 10 astronauts aboard the docked station and shuttle Discovery bounced off Kibo?s curved walls, struck poses for photographs and performed weightless somersaults and flips.

?It was just the coolest moment for me,? space station flight director Annette Hasbrook said of the opening. ?You watched them just fly in, and they shot through the module. It was just outstanding.?

Weighing in at nearly 15 tons, Japan?s Kibo laboratory is the largest room ever launched to the space station. It is almost 37 feet (11.2 meters) long, about 14.4 feet (4.4 meters) wide and has its own airlock, two windows and a robotic arm. Japanese engineers are watching over the new module from the country?s Tsukuba Space Center to the north of Tokyo.

Built by the Japan Aerospace Exploration Agency (JAXA), the main Kibo lab launched toward the space station last Saturday aboard NASA?s shuttle Discovery. The shuttle?s STS-124 astronaut crew, commanded by veteran U.S. spaceflyer Mark Kelly, is charged with performing three spacewalks to install Kibo and swap out one member of the station?s three-man crew.

Astronauts will add a second piece to the Kibo facility, an attic-like storage module already aboard the station, on Friday. A third segment - a porch-like external platform for experiments and a smaller robotic arm - are slated to be launched to the station next year.

The new laboratory is so large it was launched nearly empty, with many of its equipment racks tucked away in its storage module atop the station?s hub-like Harmony connecting node. Kelly has called Kibo?s main room the ?Lexus of space station modules.?

?I know it?s been like 20 plus years to get this module up in space,? Hoshide said of Kibo, whose name means ?hope? in Japanese. ?It?s a beautiful module, and we have a new ?hope? on the space station.?

Kibo?s successful opening came just hours after station astronauts successfully repaired a broken Russian space toilet aboard the orbiting laboratory, and one day after the new Japanese module itself was installed during a Tuesday spacewalk.

Shuttle astronauts also successfully tested the delicate laser and camera sensors at the tip of Discovery?s heat shield inspection boom, which they retrieved Tuesday after months in storage outside the station.

The main Kibo laboratory is the third new room to be added to the station this year. In addition to its storage room and a Canadian maintenance robot, which a previous shuttle crew delivered in March, the station also received the European Space Agency?s $2 billion Columbus laboratory during a February shuttle flight.

?We?re missing the Europeans and the Canadian crewmembers up here, but this is an international program,? Hoshide said. ?The Kibo lab is open!?

With Japan?s new space lab open for business, astronauts aboard Discovery and the station will now turn their attention to their next spacewalk on Thursday, a 6.5-hour excursion aimed at priming Kibo for orbital spaceflight.

?We will continue another busy day tomorrow,? said Tetsuro Yokoyama, JAXA?s deputy Kibo operations project manager.

NASA is broadcasting Discovery's STS-124 mission live on NASA TV on Saturday. Click here for SPACE.com's shuttle mission updates and NASA TV feed.