THERE’S SOME DEBATE OVER WHAT ACTUALLY CAUSED THE ACCIDENT
There’s some debate over what actually caused the accident. Orbital and NASA both agree that there was an explosion in one of the engine’s turbopumps — the spaghetti-like tubes that aid combustion. Yet no one seems to know what caused that explosion. Orbital seems to think there was a defect in the turbopumps, stemming from how the engines were made. If so, that would place the blame on the engines’ manufacturer, Aerojet Rocketdyne. However, NASA says it could be a problem with the engine design in general — or it may not be the fault of the engines at all. Foreign objects made of titanium and silicon were found in the engines at the crash site, which could indicate that Orbital didn’t assemble the rocket correctly.
Regardless of the actual cause, Orbital opted to get rid of the Aerojet engines in the Antares and will replace them with ones built by Russian company NPO Energomash. The updated Antares won’t be ready to launch until next year, though, and Orbital still needs to perform four resupply missions for NASA through the end of 2016. So in the meantime, the company will launch two resupply missions with its Cygnus cargo spacecraft atop an Atlas V, the premiere rocket manufactured by the United Launch Alliance. The first of those flights is scheduled for December 3rd.