After a week of flying together, shuttle Atlantis undocked from a larger and virtually completed International Space Station on Sunday and headed for home on its final voyage. 
 
 In this May 21, 2010 photo provided by NASA, astronauts Michael Good, foreground, and Garrett Reisman, STS-132 mission specialists, works during the flight's final space walk at the International Space... (Associated Press) 
 
 In this May 21, 2010 photo provided by NASA, astronauts Michael Good, foreground, and Garrett Reisman, STS-132 mission specialists, works during the flight's final space walk at the International Space... (Associated Press) 
 
 In this May 21, 2010 photo provided by NASA, astronaut Michael Good, STS-132 mission specialist, as seen from the space shuttle Atlantis' forward cargo bay, works during the flight's final space walk... (Associated Press) 
 
 The two orbiting craft parted company 220 miles (354 kilometers) above the Indian Ocean. Once more, the space station astronauts thanked their shuttle friends for all their help and urged them to "stay safe." 
 
 Atlantis isn't set to land until Wednesday. On Monday, the six crewmen will conduct one last safety inspection of their ship. 
 
 "Take care," the space station's Russian skipper, Oleg Kotov, told his shuttle visitors right before the hatches were sealed for undocking. 
 
 "We'll see you all on the surface of planet Earth again soon," said Atlantis' commander, Kenneth Ham. 
 
 The two commanding officers shook hands twice and laughed, then embraced. Their crewmates _ representing the United States, Russia and Japan _ followed suit. 
 
 Earlier in the morning, Ham told reporters the two crews had fun. He said all 12 space fliers bonded through hard work and performed as a single team. 
 
 The space station is bigger and packs more power, thanks to Atlantis and its crewmen. They left behind a new Russian compartment packed with supplies, as well as six fresh batteries and other equipment that was hooked up during a series of spacewalks. 
 
 Its total mass exceeds 816,000 pounds (370,000 kilograms), and it's 98 percent complete in terms of living space. 
 
 "This place is now a palace. It's huge, and I've had great fun exploring it," said shuttle astronaut Piers Sellers. "We're seeing station in pretty much its final form, and it's really magnificent." 
 
 Two shuttle missions remain to wrap up NASA's share of construction. Discovery is scheduled to fly in September, followed by Endeavour in November. 
 
 As it currently stands, once Atlantis lands, it will never fly in space again. 
 
 NASA and some politicians are pushing hard for another mission, however, so Atlantis can haul up a final load of supplies in June 2011. The White House _ which wants NASA concentrated on getting astronauts to asteroids and Mars in the coming decades _ would need to approve any extra flights. 
 
 Already, NASA is going through the list of museums interested in Atlantis and Endeavour. Discovery is promised to the Smithsonian Institution. 
 
 During a news conference Sunday morning, the Atlantis astronauts were asked where they would like to see their ship wind up. Pilot, Dominic "Tony" Antonelli pointed out that none of them gets to decide. But if he got to pick, Atlantis would retire to his backyard in Houston. 
 
 "I get plenty of letters from my home owners' association about leaving my garbage can out and not keeping my grass trimmed, but if I got Atlantis parked in my back yard, that would make all those letters just kind of disappear," Antonelli said with a smile. 
 
 As for Atlantis' more immediate future, the astronauts still need to survey its wings and nose in search of any damage. They'll perform the job Monday using the newly repaired inspection boom. A spacewalking crewman untangled a cable on the boom last week, allowing the TV camera on the end to tilt properly. 
 
 Over at the space station, meanwhile, three of the six residents soon will be checking out. Russia's Kotov, NASA's Timothy (TJ) Creamer and Japan's Soichi Noguchi will depart June 2 in a Soyuz capsule and aim for Kazakhstan. 
 
 After more than five months in orbit, Creamer said Sunday he can't wait to drink something without sipping through a straw and to eat food that stays on the plate. Noguchi yearns for a hot springs bath. 
 
 ___ 
 
 Online: 
 
 NASA: http://www.nasa.gov/mission_pages/shuttle/main/index.html ||||| Story highlights NASA says the space station and crew were never in any danger 
 
 A cooling pump shut down after hitting a temperature limit 
 
 An emergency spacewalk could be necessary, but it's too soon to tell 
 
 NASA scaled back operations on the International Space Station on Wednesday after discovering a problem with a cooling system. 
 
 A pump on one of the station's two external cooling loops shut down after hitting a temperature limit, NASA said. 
 
 Teams worked to get the cooling loop back up and running, NASA said. Experts suspect a malfunctioning valve may have caused the problem, but they're still trying to figure out how to fix it. 
 
 The station and crew aboard were never in any danger, NASA said. 
 
 Officials could determine that an emergency spacewalk is the best way to fix the failed pump -- something they've done in the past. 
 
 NASA said Thursday that there has been no decision on the spacewalk, and it may be a couple of days before the decision is made, according to Kenny Todd, the ISS mission management team chairman. 
 
 Photos: Notable moments of the International Space Station Photos: Notable moments of the International Space Station The crew of the space shuttle Atlantis took this picture of the International Space Station after leaving it in July 2011. Atlantis was the last shuttle to visit the station, which was first launched in 1998 and built by a partnership of 16 nations. Hide Caption 1 of 13 Photos: Notable moments of the International Space Station The crew of the space shuttle Endeavour initiates the station's first assembly sequence in 1998. The International Space Station includes several large modules, each launched separately and connected in space by astronauts. Hide Caption 2 of 13 Photos: Notable moments of the International Space Station The Zarya control module, on the left with the solar panels, floats above Earth with its newly attached Unity module after the first assembly sequence in December 1998. Hide Caption 3 of 13 Photos: Notable moments of the International Space Station The first crew of the International Space Station, seen on board in December 2000. From the left are cosmonaut Yuri P. Gidzenko, astronaut William M. Shepherd and cosmonaut Sergei K. Krikalev. Hide Caption 4 of 13 Photos: Notable moments of the International Space Station The Endeavour crew installs the first set of U.S. solar arrays on the station in 2000. Hide Caption 5 of 13 Photos: Notable moments of the International Space Station In March 2001, a space shuttle delivered the station's second crew and brought the first one home. It also brought Leonardo, the station's first Multi-Purpose Logistics Module, to the station. Leonardo carried supplies and equipment. Hide Caption 6 of 13 Photos: Notable moments of the International Space Station In September 2006, the space shuttle Atlantis docked with the space station, delivering solar wings and a new truss. Hide Caption 7 of 13 Photos: Notable moments of the International Space Station The space shuttle Discovery leaves the space station in March 2008 after its crew successfully delivered and installed the Japanese-built Kibo lab. Hide Caption 8 of 13 Photos: Notable moments of the International Space Station The unmanned SpaceX Dragon spacecraft connects to the space station in May 2012. It was the first private spacecraft to successfully reach an orbiting space station. Hide Caption 9 of 13 Photos: Notable moments of the International Space Station An unmanned Russian cargo craft disconnects from the space station in April 2013. The station relies heavily on ships to bring up supplies. Hide Caption 10 of 13 Photos: Notable moments of the International Space Station Commander Koichi Wakata of the Japan Aerospace Exploration Agency peers out of the space station's Cupola observatory on April 27. The Cupola is a dome-shaped module that allows station crew members to observe and guide activities outside the station. Hide Caption 11 of 13 Photos: Notable moments of the International Space Station A Russian Soyuz spacecraft is docked with the space station on May 5. Since the U.S. shuttle program ended in 2011, all crew members are ferried to and from the space station on Russian rockets. Hide Caption 12 of 13 Photos: Notable moments of the International Space Station A Soyuz spacecraft is seen on May 13 as it lands in Kazakhstan with Wakata and other members of the his Expedition 39 crew. Hide Caption 13 of 13 
 
 The external cooling loops are systems that circulate ammonia outside the station to keep equipment cool. 
 
 Officials discovered the malfunctioning loop was producing too much ammonia Wednesday morning, NASA spokesman Josh Byerly said. 
 
 Teams have shut down some noncritical systems on the station as a result of the problem, NASA said. 
 
 The space station's life support system is still up and running. 
 
 The current mission of the space station, officially called Expedition 38, is scheduled to go until March 2014. 
 
 The six-person crew consists of NASA astronauts Mike Hopkins and Rick Mastracchio of the United States; Russians Mikhail Tyurin, Sergey Ryazanskiy and Oleg Kotov; and Koichi Wakata of Japan.
– Space shuttle Atlantis undocked from the International Space Station for the last time this morning and began its return trip to Earth. With Tony Antonelli at the helm, the shuttle did an inspection lap around the nearly complete ISS before its 3-day trip home, reports Florida Today. "This place is now a palace," one astronaut told the AP about the space station. "It's huge, and I've had great fun exploring it."