The space shuttle Atlantis just took off on what is expected to be its last mission in space.
It launched from the Kennedy Space Center in Florida.
As NPR's Nell Greenfieldboyce explained on Morning Edition:
"Atlantis is supposed to be the first shuttle in the aging fleet to stop flying. During its planned final mission, the shuttle will carry up a Russian-built research lab that's part of NASA's collaboration with other countries to construct the international space station.
"But after the astronauts return, NASA workers at Kennedy Space Center in Florida will make Atlantis ready to fly again.
"That's because Atlantis will be on stand-by as a just-in-case rescue vehicle in the event that there's trouble during the very last shuttle flight ever. Right now, the honor of that final mission has fallen to Endeavour, which is scheduled to launch in November."
And there is also a chance, Nell reported, that NASA might decide to give Atlantis one more trip to take additional spare parts and other essentials to the space station.
NASA TV is webcasting the mission here.
Florida TODAY has a webpage devoted to Atlantis' history. Its first launch was on Oct. 3, 1985.