Orbital Delays Orb-2 Mission Again as Engine Test Failure Investigation Continues

Orbital Sciences Corporation announced today that it is again delaying the launch of Orb-2, its second operational cargo resupply mission to the International Space Station (ISS), while it continues to investigate the failure of an AJ-26 rocket engine during a test at Stennis Space Center.

Orb-2 was originally scheduled for May 6, but was initially delayed when SpaceX had to postpone one of its ISS cargo missions.   The two companies are competitors in the ISS cargo resupply business.  NASA and its international partners manage a dizzying array of missions taking crew and/or cargo to the ISS plus occasional spacewalks and a delay in any one activity can have a domino effect on the others.

Orbital was working towards a June 10 launch date when the engine test failed on May 22.   It postponed the launch to no earlier than (NET) June 17 and now it is NET July 1.   Orbital’s announcement stressed that July 1 is just a planning date, not an official launch date.

AJ-26 engines are Russian NK-33 engines built more than four decades ago.  They are imported to the United States and refurbished by Aerojet Rocketdyne and redesignated AJ-26.   The engine that failed on May 22 is intended to be used in a launch next year and was undergoing a routine acceptance test after refurbishment.  

The engines are used to power Orbital’s Antares rocket, which sends the Cygnus cargo spacecraft to the ISS.  These launches takes place from the Mid-Atlantic Regional Spaceport (MARS) at NASA’s Wallops Flight Facility on the coast of Virginia.