NK-33. The RD-180 engines were used (as of 2016) to power the Atlas V rocket. This company also acquired a license for the production of new engines. Sale of engines to Aerojet About 60 engines survived in the "Forest of Engines", as described by engineers on a trip to the warehouse. In the mid-1990s, Russia sold 36 engines to Aerojet General for $1.1 million each, shipping them to the company facility in Sacramento CA. During the engine test in Sacramento, the engine hit its specifications. Aerojet has modified and renamed the updated NK-33 to AJ26-58, AJ-26-59 and AJ26-62, and NK-43 to AJ26-60. Kistler K-1 Kistler Aerospace, later called Rocketplane Kistler (RpK), designed their K-1 rocket around three NK-33s and an NK-43. On August 18, 2006, NASA announced that RpK had been chosen to develop Commercial Orbital Transportation Services for the International Space Station. The plan called for demonstration flights between 2008 and 2010. RpK would have received up to $207 million if they met all NASA milestones, but on September 7, 2007, NASA issued a default letter, warning that it would terminate the COTS agreement with Rocketplane Kistler in 30 days because RpK had not met several contract milestones. Antares The initial version of the Orbital Sciences Antares light-to-medium-lift launcher had two modified NK-33 in the first stage, a solid Castor 30-based second stage and an optional solid or hypergolic third stage. The NK-33s were imported from Russia to the United States, modified, and re-designated as Aerojet AJ26s. This involved removing some electrical harnessing, adding U.S. electronics, qualifying it for U.S. propellants, and modifying the steering system. In 2010 stockpiled NK-33 engines were successfully tested for use by the Orbital Sciences Antares light-to-medium-lift launcher. The Antares rocket was successfully launched from NASA's Wallops Flight Facility on April 21, 2013. This marked the first successful launch of the NK-33 heritage engines built in early 1970s. Aerojet agreed to recondition sufficient NK-33s to serve Orbital's 16-flight NASA Commercial Resupply Services contract. Beyond that, it had a stockpile of 23 1960s- and 1970s-era engines. Kuznetsov no longer manufactures the engines, so Orbital sought to buy RD-180 engines. Because NPO Energomash's contract with United Launch Alliance prevented this, Orbital sued ULA, alleging anti-trust violations. Aerojet offered to work with Kuznetsov to restart production of new NK-33 engines, to assure Orbital of an ongoing supply. However, manufacturing defects in the engine's liquid-oxygen turbopump and design