This story was updated at 9:20 a.m. EDT.
CAPE CANAVERAL, Fla. ? The space shuttle Atlantis sailed back to Earth Wednesday to make a flawless landing in Florida, ending what is expected to be its final trip to space after 25 years of flight.
With two resounding sonic booms, Atlantis announced its arrival just minutes before landing at NASA's Kennedy Space Center with commander Kenneth Ham at the controls. Touchdown occurred at 8:48 a.m. EDT (1248 GMT) to cap the last scheduled mission for Atlantis.
"That was pretty sweet," Mission Control radioed Ham. "For you and your crew, that was a suiting end to an incredible mission."
Rain showers that threatened to postpone the landing did not materialize, and Atlantis was able to land during its first planned opportunity. Returning to Earth with Ham were pilot Dominic "Tony" Antonelli and mission specialists Garrett Reisman, Michael Good, Stephen Bowen and Piers Sellers.
The astronauts completed a 12-day flight to the International Space Station to deliver a new Russian research room and a host of spare supplies, including new batteries and a communications antenna. The shuttle launched May 14.
"From our point of view it's been a very successful mission," Good told reporters Tuesday. "We took up a new space-to-ground antenna, a new six-pack of batteries? we brought up a new Russian module, so we added to the space inside of the International Space Station."
Atlantis and her sister shuttles Endeavour and Discovery are due to be retired this year after two more missions, planned for September and November.
"This is the 32nd mission for Atlantis," mission specialist Stephen Bowen said Tuesday from space. "It's served our country really well. It's part of a legacy of exploration that we hope will continue."
Overall, Atlantis has travelled more than 120 million miles during its spaceflight career and visited quite a few destinations, including the former Russian Mir space station, the Hubble Space Telescope, and of course, the International Space Station.
"I hope that when she lands successfully? she'll go somewhere and get the respect she deserves as a ship of exploration," mission specialist Piers Sellers said in a video the Atlantis crew made from space to commemorate the shuttle's last mission.
On this trip the astronauts carried with them an American flag flown on Atlantis' first flight, the STS-51J mission in October 1985.
The orbiter is named after the RV Atlantis, a two-masted sailing ship that served as a research vessel for the Woods Hole Oceanographic Institute in Woods Hole, Mass.
"She has definitely lived up to her name over the past 20 years or so," Bowen said.
After retirement, all three space shuttles will be sent to museums around the country, while NASA focuses on the next step in human spaceflight.
U.S. President Barack Obama has proposed encouraging private companies to develop the next spaceships to carry astronauts to low-Earth orbit and the space station. Meanwhile, NASA would work on designing a heavy-lift vehicle that could propel humans farther out in the solar system to visit an asteroid or Mars.
Though this mission is the final planned flight for Atlantis, there is a chance the shuttle could fly again. The orbiter is slated to be the backup shuttle for the last planned mission, the STS-134 flight of Endeavour in late November. If there is an emergency with that shuttle, Atlantis could lift off to rescue the astronauts.
To be safe, NASA will process Atlantis one last time on the ground so it is ready for launch if necessary.
Some within NASA and Congress hope to secure funding to turn that rescue mission into one more final shuttle flight to deliver even more supplies to the space station. If approved by the White House, that mission would likely fly in June 2011.
Outfitting the station
Ham and his crew departed the space station on Sunday, capping off a hectic mission that included three spacewalks to install the new parts on the orbiting lab.
The new hardware will help outfit the station for the era after the space shuttles retire, taking with them their large cargo-carrying capacity. Russian Soyuz spacecraft and unmanned Russian and commercial cargo vehicles will continue to travel to the orbiting lab, but none can fit payloads as large as the shuttles can.
This flight of Atlantis was the third of five shuttle missions planned for 2010.
"She's been an amazing ship and it's an honor to have served upon her," Reisman said.
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SPACE.com is providing complete coverage of Atlantis' STS-132 mission to the International Space Station with Senior Writer Clara Moskowitz in Cape Canaveral, Fla., and Managing Editor Tariq Malik based in New York. Click here for shuttle mission updates and a link to NASA TV.