Space shuttle Atlantis is set to blast off on its final flight next week, heading to the International Space Station, carrying up a crew of six and a load of supplies. NASA's top managers agreed Wednesday to set May 14 as the launch date. Liftoff would be at 2:20 P.M. (1820 GMT). Much of the payload is crammed inside a Russian-built module that will be attached permanently to the orbiting lab complex. The astronauts will venture out on three spacewalks to plug in fresh batteries and tack on a spare antenna. The 12-day mission is scheduled to be the last for Atlantis. NASA is retiring its three shuttles at the end of this year. After this flight, only two will be left. But Atlantis won't be dismantled and head to a museum when the flight is over. Instead, the spaceship will be prepped for a potential rescue mission for NASA's very last shuttle flight. That final trip, by Endeavour, is scheduled for November at the earliest. Discovery is supposed to make its last trip in September.