NASA has cleared a privately-made cargo ship for a test flight to the International Space Station that is scheduled to launch in less than two weeks.
The Dragon mission would be the first time a privately owned and operated vessel visits the space station, a US$100 billion research laboratory that orbits about 380 kilometres above Earth.
NASA is counting on Space Exploration Technologies, also known as SpaceX, and a second company, Orbital Sciences Corporation, to keep the space station stocked with supplies and science experiments following the retirement of the space shuttles last year. The companies' combined contracts for cargo deliveries are worth US$3.8 billion.
"In order for space station to be successful, these systems have to be there for us," says space station program manager Mike Suffredini.
"We're really rooting for the teams to come through," adds NASA Associate Administrator Bill Gerstenmaier.
So far, NASA has invested US$381 million in the SpaceX rocket and cargo capsule, with the company and investors contributing about another US$700 million, says SpaceX founder and Chief Executive Elon Musk.
The Falcon 9 rocket and Dragon capsule also are in the running to serve as a space taxi for astronauts. The United States hopes to break Russia's monopoly on flying crews to the station, a service that costs more than US$60 million per person, by 2016 under a related NASA program.
"This is a test flight and we may not succeed on getting all the way to the space station," says Musk. "I think we've got a pretty good shot, but it's important to acknowledge that a lot can go wrong. This is pretty tricky."
If the launch is successful, the Dragon capsule would conduct a series of manoeuvres and tests in orbit before NASA clears it for approach and berthing at the station, which is targeted for 3 May. It would remain attached to the outpost for several weeks before flying back to Earth and splashing down in the Pacific Ocean for recovery.
The capsule will carry 521 kilograms of food and non-critical equipment and supplies to the station. It is expected to return 660 kilograms of cargo back to Earth, a capability that far exceeds what the Russian Soyuz capsules can hold.
The European and Japanese ships that also fly cargo to the station incinerate in the atmosphere after making deliveries and do not return to Earth.
NASA plans a final review of the Dragon mission next week to verify SpaceX flight software. The Falcon 9 rocket is scheduled for launch at 1:22 am AEST (16:22 GMT) on 1 May, with a backup launch opportunity four days later.