By Irene Klotz
CAPE CANAVERAL, Florida (Reuters) - Space shuttle Discovery with seven astronauts aboard blasted off on Monday on one of NASA's final servicing missions to the International Space Station.
With a brilliant flash of light and a thundering roar, the shuttle lifted off at 6:21 a.m. EDT (11:21 a.m. British time), shattering the pre-dawn calm around the Kennedy Space Centre in Florida.
"Enjoy the ride," shuttle test director Laurie Sally radioed the crew minutes before liftoff.
The shuttle is carrying an Italian-built cargo hauler filled with equipment, experiments, food and supplies for the space station, which is expected to be finished in September after 12 years of construction about 220 miles (355 km) above Earth.
The United States plans to stop flying its trio of space shuttles after three more missions to stock the outpost with spare parts and gear too big or bulky to fit on other spaceships. The shuttles, which can carry about 50 tons to the station's orbit, are being retired due to cost and safety concerns.
NASA will then turn over cargo deliveries to two commercial firms -- privately held Space Exploration Technologies of California and Orbital Sciences Corp of Virginia. Station partners Russia, Europe and Japan also have vessels that can haul cargo to the outpost.
Crew transport already is handled exclusively by Russia, which flies its three-person Soyuz capsules at a cost of $51 million (33.5 million pounds) per seat.
The Obama administration is proposing to boost NASA's budget by $6 billion over five years to seed development of commercial space taxis in the United States.
Space Exploration Technologies, or SpaceX, plans to debut its Falcon 9 rocket next month on a demonstration mission.
Founder and chief executive Elon Musk, a multimillionaire Internet entrepreneur, says it will take about three years to develop a launch escape system so SpaceX's Dragon capsule can carry people.
Other firms, including Boeing and United Launch Alliance, a joint venture of Lockheed Martin and Boeing, are working on space taxi development under NASA grants.
(Reporting by Irene Klotz; Editing by Tom Brown and Chris Wilson)
