Astronauts on board the International Space Station have been forced to wait for a delivery of groceries after the launch of the first private spacecraft due to resupply them was aborted at the last minute after an engine problem.
The SpaceX Falcon 9 rocket had been due to take off from Cape Canaveral on a mission to dock a capsule with the space station to provide supplies for the six astronauts currently living in orbit around the earth.
Although described as a "grocery run", the mission would have marked a milestone in space exploration as it would have been the first time a private company had taken over the job of delivering cargo to the space station.
The countdown for the launch was aborted just moments before take-off after an automatic shutdown of the rocket engines despite the ignition sequence already being under way.
The rocket remained on the launch pad amid a cloud of exhaust fumes. Officials suspect a problem with engine pressure caused the on-board computers to abort the launch.
"Launch aborted: slightly high combustion chamber pressure on engine 5. Will adjust limits for countdown in a few days," SpaceX founder Elon Musk explained on the microblogging site Twitter.
A SpaceX spokesman said engineers would look into the causes, but that the issue was not believed to be something entirely new.
Another attempt to launch the unmanned rocket will take place on Tuesday if the problem can be fixed.
SpaceX is among five private companies who are vying to transport cargo and eventually astronauts into orbit following the retirement of NASA's space shuttle last year.
SpaceX's Dragon Capsule, which is carrying 1,000lbs of provisions for astronauts on board the ISS, was to be the first private space vehicle to attempt to dock with the space station.
The craft was loaded with non-essential supplies including half a tonne of food and other pantry items in case the flight went awry.
The Dragon Capsule is scheduled to operate in space for around three weeks, including the rendezvous with the space station.
The flight was due to be a key test for the company and NASA as they change the fundamental approach to space flight, which until now has been carried out by national space agencies rather than private companies.
A statement on NASA's website said: "NASA engineers and flight controllers are closely working with SpaceX ahead of this flight to coordinate the intricate approach, rendezvous and birthing plans needed for this historic demonstration mission to the International Space Station.
"Early data shows that the chamber pressure on engine 5 was high. The teams will continue to look at the data and assess a launch attempt on May 22."