The test launch of Orbital Sciences’ [ORB] Antares medium-class rocket was postponed at press time yesterday, according to NASA.

Orbital said on Twitter the postponement was due to a “loss of an umbilical to the second stage of Antares” The launch was called off within 12 minutes of the scheduled 5 p.m. EST departure.

Neither NASA nor Orbital provided further details at deadline yesterday on when the test launch might take place next.

The test flight is the first of two missions Orbital is scheduled to conduct in 2013 under its Commercial Orbital Transportation Services (COTS) contract with NASA. Following a successful test launch, Orbital will carry out a full flight demonstration of Antares and its Cygnus cargo delivery system to the International Space Station (ISS) around mid-2013.

Orbital is also scheduled to launch the first of eight operational cargo resupply missions to the ISS in 2013 under the Commercial Resupply Services (CRS) contract with NASA.