As 2012 ended, Orbital was carrying out a series of countdown dress rehearsals in which fuel was pumped to an Antares first stage. The two-engine first stage, positioned on its MARS launch pad on Oct. 1. was to undergo an independent 29-sec. hot fire test in January.

The workload seemed likely to push a COTS required orbital test flight of the Antares with a Cygnus mass simulator into February 2013, Beneski said. The test flight does not involve a space station rendezvous.

SpaceX carried out a similar test of its Falcon 9 rocket with a Dragon mass simulator in December 2010, 18 months later than initially planned. Initially, Orbital envisioned a March 2011 test flight.

Orbital came to the COTS initiative in February 2008, replacing Rocketplane Kistler, which had missed a series of early technical and financial milestones. Like Rocketplane Kistler, SpaceX was a winner in an earlier COTS competition in August 2006.

Orbital and SpaceX were eligible for $396 million and $288 million, respectively, in NASA funding as they completed discrete development milestones. In addition, each was eligible for a $10 million fee for the delivery of cargo to the station on its final COTS rendezvous demonstration.

Cygnus will likely deliver about 1,000 lb. of supplies on its first station flight. The capsule is designed to haul up to 4,400 lb. of supplies. Orbital plans to introduce an extended version of Cygnus that can carry nearly 6,000 lb. after its series of eight commercial re-supply missions get underway.

Unlike Orbital, SpaceX’s Dragon was developed to bring station research equipment and hardware in need of refurbishment back to Earth.

Whenever the first unpiloted Cygnus supply craft approaches the space station, Orbital can be assured that two or more astronauts aboard have been trained for the delicate task of tracking, capturing and berthing the capsule with the station’s 58-ft.-long Canadian robot arm.

“The date is still in flux, and they are trying to make sure they do it right,” said Canadian astronaut Chris Hadfield, who is scheduled to be in command of the station in April and a likely participant in the capture activities. NASA astronaut Kevin Ford, the station’s current commander, as well as early 2013 NASA crew members Tom Marshburn and Chris Cassidy will be prepared as well.