In October last year, an Antares rocket, which was carrying supplies to the International Space Station (ISS), exploded a few seconds after the liftoff. There were no injuries, but the Cygnus spacecraft that the rocket was carrying was destroyed in the mishap. Soon after that, Orbital Sciences Corp. and AJ26 rocket supplier embroiled in a debate over the explosion.

Orbital ATK blamed fault in a turbopump for the accident, while Aerojet Rocketdyne said Foreign Object Debris (FOD) was the culprit. Now, the National Aeronautics and Space Administration (NASA) has revealed that it was not FOD, but AJ26's turbopump that was responsible for the explosion.

After reviewing the accident, NASA noted that FOD should not be blamed for the loss. In a recent 10-page report, the space agency said that no clear evidence was found in the investigation which could prove that FOD directly or indirectly was the likely cause.

NASA's Independent Review Team (IRT) has brought the discussion of what was the reason behind the failed mission to the AJ26s. According to the IRT, NASA believed that Orbital ATK's take on the explosion was correct. The IRT noted, "Forensic investigation performed by Orbital ATK and NASA discovered the presence of a defect on the turbine housing bearing bore that was not consistent with baseline design requirements".

The report also disclosed that another AJ26, which underwent testing about 17 years ago, had the same flaw. As per the report, two engines failed at E-1 Test Stand at Stennis Space Center located in Mississippi at NASA.