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NASA issues report on Orbital Sciences Antares rocket launch failure

04 November 2015

A NASA report into the October 2014 loss of an Antares rocket shortly after liftoff, released by the agency on October 29, concluded there was an explosion in the liquid oxygen turbopump in one of the two engines in the first stage about 15 seconds after ignition. The vehicle lost thrust and crashed to the ground near its launch pad at the Wallops Island facility in Virginia.

Antares rocket explosion - Image: Joel Kowsky, NASA
Antares rocket explosion - Image: Joel Kowsky, NASA

The explosion destroyed 2,250 kilos of supplies destined for the International Space Station (ISS) and wrecked the launch pad.

NASA said the explosion was triggered when rotating and stationary components in part of the turbopump came into contact. This frictional rubbing led to ignition and fire in the turbopump, and thus the explosion, the report states.  The cause of the explosion remained unclear, but was due to either poor engine design, debris in the engine, or a manufacturing defect.

The Orbital Sciences Corp. rocket was powered by two AJ-26 engines, made in the former Soviet Union more than 40 years ago and refurbished in the US by Aerojet Rocketdyne.

The report found that both Aerojet and Orbital lacked sufficient information about the AJ-26 engine, including failure history dating back to its Soviet origins. “A lack of design and operating insight into the AJ-26 engines creates a low level of confidence in loss-of-mission predictions made by Orbital ATK and Aerojet Rocketdyne,” the report states.

Orbital’s own Accident Investigation Board agreed with NASA’s conclusion that elements of the turbopump came into contact and ignited the fire that caused the explosion.

The Orbital report, though, identified a single highly probable technical root cause of the failure: a machining defect in turbine assembly of the turbopump that dates back to when the engine was manufactured decades previously. An adjacent piece of the engine, recovered with little damage after the explosion, showed a “clear defect” in its machining, according to the report.

Aerojet announced on September 24 it would pay Orbital $50 million to end the dispute between the companies over the accident.

Orbital is replacing the AJ-26 engine with the more recent Russian RD-181 design, and a static test of the first Antares equipped with RD-181 engines is scheduled for early 2016. The first launch is planned for May, with ISS resupply flights resuming later in the year.

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