Virgin Galactic said its SpaceShipTwo rocket plane suffered an "in-flight anomaly" during a powered test flight on Friday that resulted in the loss of the aircraft.
"During the test. the vehicle suffered a serious anomaly resulting in the loss of the vehicle," the company said in a statement. "The WhiteKnightTwo carrier aircraft landed safely. Our first concern is the status of the pilots, which is unknown at this time."
Two pilots fly in SpaceShipTwo's cockpit during a test. Those pilots are equipped with parachutes, and after the anomaly, at least one chute was reportedly sighted over the Mojave Air and Space Port in California, the base from which SpaceShipTwo and its WhiteKnightTwo carrier plane took off.
Photographer Ken Brown, who was covering the test flight, told NBC News that he saw a midflight explosion and later came upon SpaceShipTwo debris scattered across a small area of the desert.
Bakersfield's KGET-TV quoted the Mojave airport's director, Stuart Witt, as saying that the craft crashed east of Mojave. He said a news conference was scheduled for 2 p.m. PT (5 p.m. ET).
The reported anomaly came after SpaceShipTwo fired up its rocket engine in flight for the first time in more than nine months. Since then, Virgin Galactic has switched the plane's fuel mixture from a rubber-based compound to a plastic-based mix — in hopes that the new formulation would boost the hybrid rocket engine's performance.
Before Friday's flight, the most recent aerial outing was on Oct. 7, when SpaceShipTwo took an unpowered, gliding flight back to the Mojave runway.
The latest test got off to a slow start. SpaceShipTwo spent more than three hours on the Mojave runway, slung beneath its WhiteKnightTwo mothership, while the ground team assessed whether the weather was right for flight. The go-ahead was finally given for takeoff at 9:19 a.m. PT (12:19 p.m. ET).
It took WhiteKnightTwo about 45 minutes to get to 50,000 feet, the altitude at which it released SpaceShipTwo for free flight.
The aim of such flights was to test SpaceShipTwo in preparation for suborbital trips to the edge of outer space, beyond 100 kilometers (62 miles) in altitude. Virgin Galactic had said SpaceShipTwo's first trip to an outer-space altitude could have taken place before the end of the year, depending on how the tests went. And the company's billionaire founder, Richard Branson, was hoping to ride on the first commercial flight next year.
More than 700 customers have paid as much as $250,000 for a ride on the rocket plane.