LOS ANGELES - NTSB and FAA accident investigators will start work on Nov. 1 with Scaled Composites to understand the causes of the Virgin Galactic SpaceShipTwo (SS2) crash at Mojave that claimed the life of one test pilot and seriously injured another.

The suborbital spacecraft's hybrid rocket propulsion system, which was being tested for the first time in flight with a new plastic-based fuel grain, is expected to form the focus for investigators. However initial evidence from photographs taken from the ground indicate the rocket, which was fueled with polyamide, a form of benign thermoplastic developed by engineers at Scaled Composites, ignited as planned following release at 45,000 ft. from the WhiteKnightTwo carrier aircraft.

Although SS2 broke up in mid-air only moments into the powered flight phase, observers who witnessed the flight suggest the rocket motor itself may not have exploded. Mojave Air and Space Port chief executive Stu Witt says, “If there was a huge explosion I didn’t see it.” Watching from the base of the Mojave control tower, Witt says, although he was warned to expect a different exhaust plume from the earlier powered tests, he saw nothing unusual. “There was a pause of about 90 [sec.]. I knew [there was a problem] when other things weren’t happening. It wasn’t because of something that did happen. It was because of what I was not hearing and not seeing.”

The vehicle, which was making its fourth powered flight out of 55 total sorties, broke into several large sections with most of the debris falling within a mile-wide zone near Koehn Lake about 30 mi. north of Mojave. The main fuselage and wings remained attached and landed inverted on the desert floor, while one of SS2’s two feathering tail booms was also photographed and looked relatively intact nearby.

Of the crew, neither of whom has yet been named, the surviving pilot was recovered successfully by helicopter from the desert with back injuries after successfully bailing out. The body of the deceased crew member is thought to have been recovered from the remains of the cockpit section, which came to rest near a road to the west of the Koehn Lake area.

Scaled Composites president Kevin Mickey says the company will meet with the NTSB and “spend a couple of hours putting together a game plan for the investigation, which we expect to take several days. We were flying a rocket motor today that had been thoroughly tested on the ground and had seen no anomalies.”

Sierra Nevada (SNC), the manufacturer of the original rocket motor used for the initial powered flight tests, has meanwhile distanced itself from the new design. The company says its technical and program involvement “ended in May of 2014 with Virgin Galactic’s announcement to use its own internally developed technology for the SS2 rocket motor.” It adds that “SNC had no involvement in the build or qualification testing of the motor used in this flight, nor in the integration of this motor to SS2. SNC was not engaged in any manner in the pre-flight safety or technical approvals or in the flight operations of the mission conducted today.”