Test-firing for Falcon 9 rocket

Falcon 9 is envisaged to carry crew to the space station

A private firm has test-fired a rocket that could soon be flying cargo and astronauts to the International Space Station (ISS).

The SpaceX company fired the engines of its Falcon 9 rocket for three minutes - the length of time taken for the launcher to climb towards orbit.

Nasa has given SpaceX "seed money" to carry out development of the rocket.

The agency hopes Falcon 9 can help fill a mission gap that will exist while it builds a successor to the shuttle.

"The full mission-length test firing clears the highest hurdle for the Falcon 9 first stage before launch," said Elon Musk, chief executive of SpaceX.

"In the next few months, we will have the first Falcon 9 flight vehicle on its launch pad at Cape Canaveral, preparing for lift-off in 2009."

At full power, the rocket generates a whopping 388,000kg (855,000lbs) of force at sea level.

The test consumed over 225,000kg (500,000lbs) of propellant. All nine of the rocket's engines fired for 160 seconds, then two engines were shut down to limit the acceleration.

The remaining seven continued firing for 18 more seconds, as would occur in a typical climb to orbit.

Falcon 9 could still complete a mission if one of its nine engines failed

The test validated the ability of the Falcon 9 to shut down engines without affecting the functioning of the remaining engines.

This demonstrates the ability of the launcher to lose engines in flight and still complete its mission successfully, much as a commercial plane is designed to be safe in the event of an engine loss.

Like a plane, the Falcon 9 engines are enclosed in a protective sheath that ensures a fire or destructive loss of an engine doesn't affect the rest of the vehicle, according to SpaceX.

The company wants Falcon 9 to make its maiden flight by the first quarter of 2009. Initially, it will just loft satellites, including the British-built-and-operated Hylas broadband and TV spacecraft.

But SpaceX aims to use the vehicle to launch its Dragon capsule soon afterwards. The capsule is being designed to carry both supplies and people to the space station.