Space shuttle Atlantis rocketed away from its seaside launch pad in Florida today on the 135th and final flight in the 30-year-old US shuttle programme.
About a million sightseers witnessed the smooth liftoff from Kennedy Space Center. They lined causeways and beaches around the central Florida site, angling for a last glimpse of the pioneering ship.
"Good luck to you and your crew on this final flight of this true American icon," shuttle launch director Mike Leinbach radioed to the crew minutes before takeoff.
"Have a little fun up there," he added.
Cloudy skies threatened to delay the 12-day mission to the International Space Station, but conditions cleared in time for blastoff.
However, the countdown was halted 31 seconds before the scheduled 11.26am EDT launch as computers detected a problem with the retraction of equipment used to vent gases from the fuel tank. Engineers quickly verified the equipment was correctly positioned and cleared the ship for launch three minutes later.
"The shuttle is always going to be a reflection of what a great nation can do when it dares to be bold and commits to follow through," said Atlantis commander Chris Ferguson.
The shuttle's cargo of tonnes of food and equipment is intended to bridge the gap until newly hired commercial freighters are ready to begin deliveries to the space station. The first flights are expected next year.
Atlantis and its four-member veteran crew are scheduled to arrive at the station, a recently completed orbital research outpost, on Sunday.
Nasa is ending the shuttle programme due to high operating costs.
"We have not found a way in this nation of being able to start a new programme, and start it robustly, while continuing with an existing programme," said Nasa deputy administrator Lori Garver.
The new focus of the US human space flight program will be the space station, a $100 billion project of 16 nations that orbits 230 miles above Earth.
Nasa will rely on Russia to fly its astronauts to the space station, at a cost of more than $50 million a seat, until commercial firms are ready to take over crew ferry flights.
Among the companies interested in the work is Space Exploration Technologies, or SpaceX, which already has a Nasa contract to fly cargo to the station.
The company, owned by Internet entrepreneur Elon Musk, successfully tested its Dragon capsule in orbit last December and hopes to make it all the way to the station during a second test flight later this year.
The other freighter, being developed by Orbital Sciences Corp, has yet to debut.
Nasa also is backing space taxi development work by Boeing Co, Sierra Nevada Corp and Blue Origin, which is owned by Amazon founder Jeff Bezos.
The US space agency also plans to use the $4 billion or so it has been spending each year to maintain and operate its three space shuttles to develop new spacecraft that can travel beyond the station's near-Earth orbit, where the shuttles cannot go.
Atlantis is scheduled to spend about a week at the space station, transferring more than 5 tonnes of food, clothing, science experiments and other gear to the station and packing up old equipment and trash that will be returned to Earth aboard the shuttle.
Ferguson, pilot Doug Hurley, flight engineer Rex Walheim and Sandy Magnus will be short-handed on the 135th and final shuttle mission.
Typically, six or seven astronauts are assigned to a flight, but the Atlantis crew has to rely on the smaller Russian Soyuz capsules for rides home in case the shuttle is too damaged to attempt landing.
Previous shuttle crews have had a second shuttle prepared to mount a rescue if needed since the 2003 Columbia accident. Atlantis's sister ships have already been retired.
Reuters