Space shuttle Atlantis thundered off its seaside launch pad Friday, rising atop a tower of smoke and flames as it left Earth on the final flight of the U.S. space shuttle program.

About 1 million sightseers lined causeways and beaches around the Kennedy Space Center in central Florida, angling for a last glimpse of the iconic ship that has defined the U.S. space program for the last 30 years.

They were nearly disappointed, as cloudy skies and nearby rain threatened to delay Atlantis’ launch on a 12-day mission to the International Space Station.

Skies cleared in time for liftoff, which was delayed for about three minutes by a last-minute technical glitch. It went ahead at 11:29 a.m. EDT.

The ship’s cargo of food and equipment is intended to bridge the gap until newly hired commercial freighters are ready to fly supply runs to the station.

The shuttle and its four-member veteran crew are scheduled to arrive at the station, a recently completed orbital research outpost, on Sunday.

Here are highlights of Atlantis’ 32nd flight:

* The shuttle’s primary payload is an Italian-built cargo hauler named Raffaello which is loaded with 8,640 pounds of food, clothing, supplies and science equipment for the space station. Additional gear is packed in the shuttle’s crew cabin.

* One spacewalk is planned during Atlantis’ mission, though it will be conducted by NASA’s two resident space station astronauts, rather than the shuttle crew.

* Only four astronauts will fly on the shuttle, instead of the usual six or seven, to accommodate the smaller Russian capsules the crew would use if Atlantis was too damaged to return to Earth. NASA has no more shuttles to mount a rescue mission.

* The shuttle carries a technology demonstration project to test how a robot can refuel and service satellites in orbit. The two-year experiment, using the station’s Dextre robot, will begin after the shuttle leaves.

* Among the tons of old equipment and trash coming back from the station on the shuttle is a broken ammonia cooling system. Engineers want to take it apart and figure out why it failed.

* Atlantis is the last of NASA’s three space shuttles to be retired. After its mission, it will go on display at the Kennedy Space Center‘s Visitors Complex in Florida.

NASA is ending the shuttle program due to high operating costs.

Instead, the United States will rely on Russia to fly its astronauts to the station, at a cost of more than $50 million a seat, until commercial firms are ready to take over the work.

The U.S. space agency also plans to develop spaceships that can travel beyond the space station’s 220-mile orbit where the shuttles cannot go.

(Editing by Tom Brown, Kevin Gray and Cynthia Osterman)