Branson's Virgin Orbit rocket fails on first launch attemptby NEWS WIRES
"The mission terminated shortly into the flight. Cosmic Girl and our flight crew are safe and returning to base," Virgin Orbit's Twitter account reported as the test was underway off the coast of California.
The plane released the rocket cleanly, but the latter developed trouble of unknown origin after igniting its first-stage engine, the company said.
Founded by British billionaire Richard Branson in 2012, Virgin Orbit wants to offer a quick and flexible launch service for operators of small satellites, weighing between 300 and 500 kilos (600 to 1,00 pounds), a market which is currently booming.
The 70-foot (21-meter) Virgin Orbit rocket, named LauncherOne, does not take off from a vertical lift off, but rather is strapped to the underside of a wing on a converted Boeing 747 named Cosmic Girl.
When it reaches the required altitude, the plane releases the rocket, whose own engine fires up to push it into Earth's orbit and place its payload in space.
The company said that the initial phase of the test worked after Cosmic Girl took off from an airfield in the Mojave desert where a number of space launch companies are based.
The plane flew to a designated area over the Pacific Ocean, off the coast of Los Angeles, for the rocket release.
"Cosmic Girl has released LauncherOne!" the company said on Twitter.
"We've confirmed a clean release from the aircraft," it added three minutes later, but noted that the mission had been terminated.
Hours later the company explained: "LauncherOne maintained stability after release, and we ignited our first stage engine, NewtonThree. An anomaly then occurred early in first stage flight. We'll learn more as our engineers analyze the mountain of data we collected today."
Before the test flight, the company had stressed that "this mission is the most technically complex thing we've tried to achieve yet."
"The first few seconds after release are where it really all comes together," it said.
Asked by AFP if the rocket had been lost, a company spokesman did not immediately respond.
The concept of launching a rocket from a plane is not new. The rocket Pegasus, developed by the Northrop Grumman group, has been around since the 1990s. But Virgin Orbit wants to make a less expensive version of the launch.
Launching a rocket from a plane is more flexible than a vertical blast off because theoretically all a company needs is an airstrip rather than a space launchpad.
Richard Branson has founded another space company, Virgin Galactic, which is using a similar concept with the goal of taking tourists into space to experience weightlessness some 50 miles (80 kilometers) above the surface of the Earth.