NASA completed its part in the construction of the International Space Station on Friday, with the final spacewalkers in the 30-year shuttle program attaching an extension boom, according to AP. «Twelve years of building and 15 countries and now it's the Parthenon in the sky and hopefully the doorstep to our future,» spacewalker Gregory Chamitoff before heading back inside. «So congratulations everybody on assembly complete.» Chamitoff said it was fitting for space shuttle Endeavour to be present at the end of space station construction since it was there for the first assembly mission in December 1998. It was the fourth spacewalk in a week for the Endeavour astronauts, who are headed back to Earth in just a few days to end NASA's next-to-last shuttle flight. One last flight in July will bring up supplies. No other significant U.S. components are due to fly to the space station, which still has a decade of life ahead. That was the job of the space shuttles _ to haul up the big building blocks as well as loads of smaller items _ and now they're retiring. The last room _ a storage closet _ was attached earlier this year. While NASA's role in space station construction is over, the Russian Space Agency plans to add at least one more chamber in another year or two, a job that will require multiple spacewalks. The Russians also will continue to provide rides to and from the orbiting lab for U.S. astronauts until private companies in America are able to take over the job. Chamitoff and his spacewalking partner, Mike Fincke, teamed up with robot arm operator Gregory Johnson to add one last finishing touch. «Assembly complete. Amazing,» Chamitoff said once the 50-foot (15-meter) boom was latched securely in place. «Boy, this is a big space station,» he marveled several minutes later. Later, flight director Derek Hassmann noted there's still a lot of work ahead to operate the outpost and keep it staffed. The station can accommodate six full-time residents; their main task is to conduct scientific experiments and help researchers understand what is needed for longer expeditions, such as going to Mars. This was the 164th spacewalk by shuttle astronauts; the first was performed back in 1983. The bulk _ 110 _ were for the International Space Station, and 23 involved the Hubble Space Telescope. Endeavour, docked at the space station through this weekend, is making its last flight before being retired to a museum in California. Atlantis will close out the shuttle program in July.
