Orbital Sciences [ORB] has delayed launch for its Orb-2 mission until no earlier than July 1, according to a company statement.

ORB-2 is the second of eight cargo resupply missions to the International Space Station (ISS) under the company’s Cargo Resupply Services (CRS) contract with NASA. Orbital said the new launch schedule reflects the timing of the investigation into the cause of an AJ26 engine failure that occurred in late May during customary acceptance testing. All other elements of the ORB-2 mission are prepared to move forward, Orbital said, including the Cygnus spacecraft, which is fueled and, except for late-load cargo, is packed with its manifest of ISS cargo.

Orbital's Antares rocket its Orb-2 Mission lifted onto the Transporter/Erector/Launcher (TEL). Photo: Orbital.
Orbital’s Antares rocket its Orb-2 Mission lifted onto the Transporter/Erector/Launcher (TEL). Photo: Orbital.

The engine that failed was designated for use in a 2015 CRS mission and was undergoing hot fire testing that all Antares AJ26 engines undergo to ensure nominal performance and acceptance for use in Antares missions. Antares main stage propulsion supplier Aerojet Rocketdyne is leading the investigation into the failure with Orbital and NASA engineers also supporting the effort. The launch will eventually take place at Wallops Flight Facility (WFF) in eastern Virginia.

Once the investigation team reaches the point in their process that they can clear Antares to launch the Orb-2 mission, a targeted launch date will be established. Orbital said its Cygnus ISS rendezvous is likely to take about three days from launch and its stay at ISS will last approximately 40 days. Aerojet Rocketdyne is a division of GenCorp [GY].