Billionaire Virgin Galactic founder Richard Branson salutes the bravery of test pilots, and vows to find out what caused the crash of his prototype space tourism rocket that killed one crew member and injured another during a news conference in Mojave, Calif., Saturday, Nov. 1, 2014.

Image Credit: AP Photo/Brian Melley

MOJAVE, Calif. - Billionaire Virgin Galactic founder Richard Branson, saluting the bravery of test pilots, vowed Saturday to find out what caused the crash of his prototype space tourism rocket, killing one crew member and injuring another.

In grim remarks at the Mojave Air and Space Port where the craft was under development, Branson gave no details of Friday's accident and deferred to the National Transportation Safety Board, whose team had just arrived.

"We are determined to find out what went wrong," he said, asserting that safety has always been the top priority of the program that envisions taking wealthy tourists to the edge of space for a brief experience of weightlessness and a view of Earth below.

"Yesterday we fell short," he said. "We'll now comprehensively assess the results of the crash and are determined to learn from this and move forward."

Branson added, however, that "we are not going to push on blindly."

More than a dozen investigators in a range of specialties were forming teams to examine the crash site, collect data and interview witnesses, NTSB Acting Chairman Christopher A. Hart told a press conference at Mojave Air and Space Port, where the winged spacecraft was under development.

Hart said the investigation will have similarities to a typical NTSB probe as well as some differences.

"This will be the first time we have been in the lead of a space launch (accident) that involved persons onboard," said Hart, noting that the NTSB did participate in investigations of the Challenger and Columbia space shuttle disasters.

Hart said he did not immediately know the answers to such questions as whether the spaceship had flight recorders or the altitude of the accident, but noted that test flights are usually well documented.

The NTSB investigators were expected to head to an area about 20 miles from the Mojave airfield where debris from Virgin Galactic's SpaceShipTwo fell over a wide area of uninhabited desert Friday morning.

Branson has been the front-runner in the fledgling space tourism industry, which has taken years longer than expected by hundreds of enthusiasts who have already put down deposits to reserve seats.

On Saturday, he said none of the money has been spent and anyone who wanted a refund could get it, but no one has asked. Rather, he said, someone signed up on the day of the accident in a show of support.

"They've been patient to date," he said of his customers. "I think most of them will be patient longer."

The spacecraft broke up after being released from a carrier aircraft at high altitude, according to Ken Brown, a photographer who witnessed the accident.

One pilot was found dead inside the spacecraft and another parachuted out and was flown by helicopter to a hospital, Kern County Sheriff Donny Youngblood said.

The accident occurred just as it seemed commercial space flights were near.

Branson once envisioned operating flights by 2007. Last month, he talked about the first flight being next spring with his son.

"It's a real setback to the idea that lots of people are going to be taking joyrides into the fringes of outer space any time soon," said John Logsdon, retired space policy director at George Washington University.

Friday's flight marked the 55th for SpaceShipTwo, which was intended to be the first of a fleet of craft. This was only the fourth flight to include a brief rocket firing. The rockets fire after the spacecraft is released from the underside of a larger carrying plane. During other flights, the craft either was not released from its mothership or functioned as a glider after release.

At 60 feet long, SpaceShipTwo featured two large windows for each of up to six passengers, one on the side and one overhead.

The accident's cause was not immediately known, nor was the altitude at which the blast occurred. The first rocket-powered test flight peaked at about 10 miles above Earth. Commercial flights would go 62 miles or higher.

The problem happened about 50 minutes after takeoff and within minutes of the spaceship's release from its mothership, said Stuart Witt, CEO of the Mojave Air and Space Port.

Virgin Galactic — owned by Branson's Virgin Group and Aabar Investments PJS of Abu Dhabi — sells seats on each prospective journey for $250,000. The company says that "future astronauts," as it calls customers, include Stephen Hawking, Justin Bieber, Ashton Kutcher and Russell Brand. The company reports receiving $90 million from about 700 prospective passengers.

Ken Baxter was one of those who had signed up to be among the first to make the flight.

Despite the disaster, Las Vegas resident Baxter said he was confident that the flight will happen one day.

"It's very sad for the test pilots, but I'm ready to go into space with Richard Branson," he said.

Friday's accident was the second this week involving private space flight. On Tuesday, an unmanned commercial supply rocket bound for the International Space Station exploded moments after liftoff in Virginia.

SpaceShipTwo is based on aerospace design maverick Burt Rutan's award-winning SpaceShipOne prototype, which became the first privately financed manned rocket to reach space in 2004.

"It's an enormously sad day for a company," Rutan told The Associated Press in a phone interview from his home in Idaho, where he has lived since retiring.

Friday's death was not the first associated with the program. Three people died during a blast at the Mojave Air and Space Port in 2007 during testing work on a rocket motor of SpaceShipTwo.

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Pritchard reported from Los Angeles. Associated Press writers David Koenig in Dallas, Susan Montoya Bryan in Albuquerque, New Mexico, Seth Borenstein in Washington, and John Antczak, Christopher Weber, Tami Abdollah and Robert Jablon in Los Angeles also contributed to this report.

News from © The Associated Press, 2014