Washington, Feb 24 (IANS/RIA Novosti): A new medium-sized American rocket intended for missions to the International Space Station has successfully completed the final ground test, its developer said.

Preliminary analysis of data from the 29-second hotfire test of the Antares launch vehicle indicate that its engines and fuelling systems are fully operational, Orbital Sciences Corporation said.

The result paves the way for the inaugural flight of the rocket, expected to take place in May, the Virginia-based company said on its website.

The hotfire test was initially slated for Feb 14, but was aborted 1.5 seconds before start due to nitrogen purge issues.

The Antares, initially known as Taurus II, is an expendable launch vehicle with a maximum payload of 5,000 kg.

It is expected to deliver the Cygnus unmanned spacecraft to the International Space Station for NASA, which has no low Earth orbital spacecraft after the retirement of the Space Shuttle in 2011.