The 13 people aboard the International Space Station will say their farewells and split up Tuesday when the crew of the shuttle Endeavour undocks from the orbiting laboratory.
Endeavour's seven-astronaut crew is due to cast off from the space station at 1:26 p.m. EDT (1726 GMT), marking an end to nearly a week and a half of construction work alongside the outpost's six residents.
"It has been a spectacular and successful docked phase, but all good things must come to an end," Mission Control told Endeavour's crew in a morning message.
The joint crew has been the highest population ever for the station and the largest single gathering in space by humans in history. All 13 astronauts, who represent each of the five major international partners building the station, plan to hold a brief farewell ceremony at about 10:23 a.m. EDT (1423 GMT).
"We've had our challenges," said Holly Ridings, lead space station flight director for the mission. "We've all worked together to overcome those challenges and complete what looks like a very, very nominal ...mission, almost exactly like we planned it."
Aside from a broken toilet and air-scrubbing device, both of which were repaired smoothly, Endeavour's mission to the station has gone smoothly, Ridings said.
The shuttle launched toward the space station July 15 on a marathon 16-day mission to the orbiting laboratory.
Its six-man, one-woman crew delivered a new member of the station's Expedition 20 crew, vital spare parts and the last piece, an external experiment porch, for the outpost's massive Kibo laboratory. Five challenging spacewalks - including two tricky excursions to replace old solar array batteries - were performed.
Built by the Japan Aerospace Exploration Agency (JAXA), the $1 billion Kibo is made up of three segments: the new porch, a giant laboratory the size of a tour bus, and a smaller storage attic, each of which had to be launched to the station separately on NASA shuttle flights over the last two years. Astronauts put the final touches on the Kibo lab during their fifth and final spacewalk on Monday.
"I can verify that, from up close, it is indeed a beautiful laboratory," Endeavour astronaut Tom Marshburn told JAXA astronaut Akihiko Hoshide in Mission Control Monday after completing work on the Kibo lab.
Endeavour will return Japanese astronaut Koichi Wakata back to Earth when it lands in Florida on Friday.
Wakata, JAXA's first long-term resident of the space station, arrived at the outpost in March and watched over his country's Kibo lab during his 4 1/2 months aboard. He was replaced by NASA astronaut Tim Kopra, who launched toward the station on Endeavour to begin his own two-month mission.
Before departing the space station for good, Endeavour will fly around the orbital laboratory in a sort of victory lap. Shuttle pilot Doug Hurley will be at Endeavour's helm during the maneuver while his crewmates snap photographs of the outpost's new look with its brand new porch.
"It's all been one big highlight," Hurley said of the mission this week. "But for every pilot, to get to fly the space shuttle and get to do the big fly-around...it's going to be a big thrill."