Two astronauts made history today as the final spacewalkers of NASA's 30-year shuttle program, completing construction of the International Space Station with the smooth addition of an extension boom. It was fitting for Endeavour to be present at the end of space station construction since it was present for the first assembly mission in December 1998. 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.
"Assembly complete. Amazing," spacewalker Gregory Chamitoff said once the 50-foot boom was latched securely in place. "Boy, this is a big space station," he marveled several minutes later. All future spacewalks—including one during the final shuttle voyage this summer—will be performed by full-time space station residents. The Endeavour astronauts wished the future spacewalkers well as the hatch to the outside was shut. About five hours into today’s spacewalk, another milestone was achieved: 1,000 hours of spacewalking at the Space Station. (Click to catch up on what Endeavour astronauts have been up to this mission.)