The orbiter – one of three NASA space shuttles – will be making its 32nd and final scheduled trip to space. Atlantis is slated to blast off from Pad 39A here at Kennedy Space Center at 2:20 p.m. EDT (1820 GMT), bound for a 12-day trip to the International Space Station.
Weather forecasts predict a 70 percent chance of good conditions for launch at NASA's seaside pad. If the shuttle cannot lift off today, NASA can try again until May 18, when it must stand down to let an unmanned Delta 4 rocket loft a GPS satellite to space.
Ground crews began loading Atlantis' giant orange external fuel tank with its super-chilled liquid hydrogen and liquid oxygen propellants this morning at 4:55 a.m. EDT (0855 GMT).
NASA is planning to retire Atlantis and its sister ships Endeavour and Discovery by the end of the year to make way for the next era in space. Just how that era will shape up is still being discussed by NASA and lawmakers.
U.S. President Barack Obama has proposed encouraging private companies to develop a spacecraft capable of launching humans to the space station, and freeing up NASA to focus on planning a way to get astronauts to a nearby asteroid and then to Mars. This plan would cancel NASA's existing Constellation program, which would build Orion spacecraft and Ares rockets as replacements for the shuttles.
Commander Kenneth Ham will lead Altantis' STS-132 crew of six veteran astronauts. Their main goal is to deliver a new Russian research lab called the Mini Research Module-1 (MRM-1). The module is called "Rassvet" in Russian, meaning "Dawn."
Atlantis will also tote up some new hardware for the station, including a space-to-ground antenna and a set of replacement batteries. The astronauts plan to complete three spacewalks to install the new module and spare parts. [How big is the International Space Station?]
Riding with Ham on this mission will be pilot Dominic "Tony" Antonelli and mission specialists Michael Good, Garrett Reisman, Piers Sellers and Stephen Bowen.
"The six of us, we seem to get along really well," Good said in a preflight NASA interview. "It's a pretty casual, laid back, enjoyable atmosphere to work in. It's just great working with everybody and I'm looking forward to having a lot of fun with them up there on orbit."
Ham, who first flew beyond Earth on the STS-124 mission of the shuttle Discovery in June 2008, said he's looking forward to returning to space.
"It kind of brings out the kid in everyone to get thrown into that extreme environment, if you will, and be able to play and smile and laugh and still get your job done, because we're professionals," Ham said. "We're up there to do a job but I think it's pretty neat to watch what happens to people in space."
Historic final flight
This is Atlantis' last scheduled flight, though the orbiter will be processed again in case it must launch on an emergency rescue trip during the final shuttle mission, the STS-134 flight of Endeavour in November.
"It's humbling and you feel honored to be there at that moment but at the same time it's bittersweet, because it's the end of an era," Reisman said of being on Atlantis' final planned crew.
An especially large crowd of astronauts and NASA crew, many of whom have flown and worked on Atlantis during previous missions, is expected to attend this afternoon's launch.
"I think after launch there will probably be a little tear in some people's eyes," NASA test director Mike Leinbach said. "I think after landing there will be. But then there'll be some celebrations too."
Copyright © 2010 Space.com. All Rights Reserved. This material may not be published, broadcast, rewritten or redistributed.