The long goodbye for NASA's space shuttle program begins today, when the space agency intends to launch Atlantis for what probably will be the vehicle's last flight. Atlantis already has blasted into space 31 times, making its arcing flights around Earth seem routine. They're anything but. The shuttle has spent 282 days in orbit, hurtling around the Earth at speeds of more than 17,000 mph. That kind of speed would get you from Houston to Galveston in under 10 seconds. 'Atlantis is really a great flying bird,' said Jerry Ross, who flew five missions aboard the 25-year-old shuttle. 'I personally think it's the best one of the fleet.' NASA's current plan -- subject to approval by the U.S. Congress, which is debating the future of U.S. human spaceflight -- is to fly Atlantis, Discovery and Endeavour each on one more flight this year to complete construction of the International Space Station. The space-based laboratory will be 98 percent complete after Atlantis' 12-day mission, scheduled to deliver a 20-foot-long Russian science module that will both house scientific experiments and add a fourth docking port to the station. NASA plans to launch the shuttle at 1:20 p.m. today. During the mission, Atlantis' six-member crew also will conduct three spacewalks to install six 400-pound batteries aboard the station that are charged by the station's solar arrays and used when the sun is behind the Earth. 'These aren't double-A's,' said one of the astronauts who will conduct a spacewalk, Michael Good. 'These are each like suitcase bigger than airlines allow without charging extra.' After Atlantis' mission has installed the Russian module, the station will have 12,705 cubic feet of living space and will weigh more than 400 tons. Atlantis has played a key role in building the station, delivering among other components the Destiny and Columbus laboratories and the Quest airlock. The shuttle also has flown several scientific missions, including launching the Galileo probe to Jupiter and Magellan probe to Venus, as well as conducting the most recent, overwhelmingly successful flight to fix and upgrade the Hubble Space Telescope. Atlantis' crew, led by Commander Ken Ham, has taken to calling the mission the 'first last flight' of Atlantis. That's because there's a chance Congress will add one remaining shuttle flight next year, or if there's a problem with the final flight of either Discovery or Endeavour, Atlantis could be used to fly a rescue mission. Still, there's a deep recognition within NASA that the nearly 30-year shuttle program is in its final days. The mission's lead flight director, Mike Sarafin, likened the final flights of each orbiter to the final season of a champion athlete who is treated with respect by opposing fans in sold-out stadiums. 'We're seeing that now with the space shuttle program,' Sarafin said. 'The last planned flight of Atlantis is definitely going to be treated with a bit of reverence.' eric.berger@chron.com Please join Eric Berger on his SciGuy blog today, beginning at 10:30 a.m., for a live chat to track Atlantis' launch at 1:20 p.m. CDT and discuss the future of human spaceflight. XXX - End of Story3D 