According to the results of the investigation into the crash of the Antares, carried out by Orbital ATK, a major cause of conflict was the Explosion of the rocket engine AJ-26, made on the basis of Soviet NK-33 and modified for the U.S. the Ukrainian KB " southern ", stated NASA.
As notified on the Internet office of NASA, in November 2014 started hearing the disaster of the Antares, which occurred in October 2014. The trial was conducted by a team of twelve, With the assistance of 31 additional employee. They were provided with access to telemetry and the necessary documents." An independent panel of NASA IRT presented a detailed analysis of the wealth of the Antares Rocket before and during launch, as well as photos and video which recorded the start and after the disaster. Based on these data, the IRT decided that the most likely cause of the catastrophe was the Explosion of Antares rocket engine AJ-26 ", – noted in the report of the Agency, RIA " Novosti ". In the report it is reported that the Explosion occurred in the turbopump for liquid hydrogen E15, resulting in a damaged rocket engine. The explosion resulted in the loss of thrust in the engine, After which the carrier fell to the ground and was completely destroyed, and the goods therein. Among the reasons that led to the explosion of a turbopump are a factory defect and entering of foreign objects. Oxygen-kerosene rocket engine AJ-26 – developed by Aerojet and licensed in the USA modification Soviet NK-33 engines for use on U.S. launch vehicles (including Antares), created by removing the small snap with original NK-33, adding U.S. electronics, adapting the engine for U.S.-made fuel, as well as equipping gimbal hinge to control the direction of thrust.
Used Antares NK-33 engines were made in the 1970s and purchased in the mid 1990-ies the company Aerojet Rocketdyne for the price of 1 million dollars. With Firm Orbital has less experience with large liquid stages and cryogenic components for the first stage of Antares was signed the contract with the state enterprise "Yuzhnoye" (Ukraine, Dnepropetrovsk). The area "South" includes the main stage of the work with fuel tanks and related equipment. On October 29, during a launch from NASA's Virginia exploded booster Antares with the American ship Cygnus. Space truck was required to deliver to the ISS 2, 29 thousand Pounds of cargo, as well as among them food and materials for scientific research. The space truck and its media, created a private American company Orbital Sciences. The Antares manned rocket engines AJ-26 made on the basis of Soviet NK-33. The version about the fact that the accident occurred because of engine AJ-26, immediately began to be discussed as the main. After the explosion of the Antares USA wanted from AJ-26. In January 2015, an agreement was signed for production and delivery to the US the Russian rocket engines RD-181. 60 Russian engines will cost the customer approximately $ 1 billion, the Price includes flight training, installation of the engine on a rocket and tests. In July Russia exported to the USA the first two rocket engine RD-181.