An Aerojet AJ26 rocket engine was delivered to NASA’s John C. Stennis Space Center on July 15, 2010. Credit NASA
The AJ26 engine used for Antares is based on a Russian NK-33 rocket engine designed and manufactured in the early 1970s in support of the failed Russian N-1 moon program. Aerojet-Rocketdyne modifies the NK-33 configuration for use on U.S. launch vehicles. For Antares, the AJ26 also includes several operational variations from the NK-33 operations originally intended for the N-1 program, such as but not limited to operation at a higher power level and engine gimballing. The AJ26 was replaced by the NPO Energomash RD-181 after the aging AJ26 started to experience failures.
Antares First-Stage Core with Two AJ26 Engines Installed Credit NASA
The old age of the engines started to cause issues. A catastrophic failure of an AJ26 during testing at Stennis Space Center in May 2014 and the Orb-3 launch failure in October 2014 were indicators that the Antares needed a newer engine. Due to concerns over corrosion, aging, and the limited supply of AJ26 engines a new deal to purchase Russian engines was struck.
Antares lifted off from Pad 0A at the Mid-Atlantic Regional Spaceport at Wallops Flight Facility on October 28, 2014 just after 22:22 UTC, carrying the Cygnus Orb-3 spacecraft. 15 seconds after Antares left the launch pad an explosion occurred linked with the AJ26. Credit NASA
AJ26 Engine on Transportation and Processing Skid Credit NASA
References:
Link https://www.nasa.gov/sites/default/files/atoms/files/orb3_irt_execsumm_0.pdf
