Investigators criticize NASA part handling in analysis of 2014 rocket explosion

Independent NASA accident investigators said the U.S. space agency should “perform a greater level of due diligence for major system components” in rockets that deliver cargo to the International Space Station following a 2014 explosion.

The recommendation came in the investigators' report on the explosion of Orbital ATK's Antares rocket that destroyed a load of cargo for the space station. It may spur calls for more oversight of NASA's use of commercial contracts to deliver cargo - and soon crew members - to the space station.

NASA shared development costs for those programs with its commercial partners, while earlier rockets were fully government-funded.

Separate accident investigations are underway to determine the cause of a SpaceX Falcon 9 rocket failure on June 28, 2015, which claimed another load of station cargo.

NASA hired both Orbital and privately held Space Exploration Technologies, or SpaceX, to fly cargo to the station after the space shuttles were retired. The U.S. space agency is working on a similar program with SpaceX and Boeing to fly crew.

Orbital, in a report obtained by Reuters from the Federal Aviation Administration on Tuesday, said the Oct. 28, 2014 Antares explosion was most likely caused by an engine manufacturing defect, while NASA said it could also have been caused by a design issue or debris in the engine.

Both investigations said a fire and explosion in the rocket engine’s liquid oxygen turbopump caused the booster to fail about 14 seconds after liftoff from Wallops Island, Virginia.

Orbital said the cause of the failure was most likely a manufacturing defect in a turbopump in one of the rocket’s two AJ-26 engines, a Soviet-era motor refurbished and resold by Aerojet Rocketdyne Holdings Inc.

Aerojet in September paid Orbital $50 million to settle the dispute.

Orbital plans to replace the AJ-26 engines with a new Russian-made engine manufactured by Russia's NPO Energomash. First flight of the refurbished Antares is expected in 2016.

The use of Russian engines is controversial – they have been banned from use in rockets carrying military payloads – but analyst Marco Caceres, with Teal Group, says NASA has no choice if they want competition. “We know the Russians build excellent engines, but we don’t know how the quality control is,” he said. “To a certain extent, it’s a moot point because NASA doesn’t have a lot of choices.” The NASA investigators said a manufacturing defect was possible in the Antares case, noting that a defect also was found in a separate AJ-26 engine that exploded during testing in May 2014. But they said it was not clear the defect alone could have caused the explosion.

The NASA probe found two other potential causes of the failure: an engine design that made the turbopump “vulnerable to oxygen fires and failures,” and silica and titanium debris found in the engine.

The probe said any one of the three potential causes, or a combination of them, could have triggered the explosion. Investigators also said Orbital and Aerojet did not have full insight into the design and operational record of the engines, which were manufactured 40 years ago for a Soviet moon program.

(Reporting by Irene Klotz; Editing by Andrea Shalal and Andrew Hay)