He gave his amazing account of survival to his father, Dr Klaus Siebold, who visited him yesterday at his modest £150,000 ranch home in Tehachapi, California, on the edge of the Mojave Desert where the spaceship crashed.
Dr Siebold, who is also a pilot, travelled to California from his home in Seattle to see his son. He told The Mail on Sunday that Peter was "in good spirits" despite suffering serious injuries, including a shattered shoulder.
Both pilots were strapped into standard pilot seats and wearing thin flight suits and emergency parachutes when SpaceShipTwo was released from its mothership WhiteKnightTwo shortly after 10am on October 31.
Miracle he survived
The craft's rocket was ignited at 50,000ft - nearly ten miles above sea level. The pilots, wearing oxygen masks, were pinned against their seats by gravitational forces as the craft accelerated at more than 900mph.
Then disaster occurred. Preliminary investigations suggest that the rocket ship's folding wings - designed to slow it down and achieve safe speeds during landing - deployed early, causing the ship to break up due to the tremendous turbulence around the craft.
Alsbury was trapped in the cockpit but Siebold was thrown clear of the wreckage or somehow unbuckled his seatbelt. He then plunged towards Earth at speeds topping 120mph.
Peter Siebold: "I must have lost consciousness at first. I can't remember anything about what happened but I must have come to during the fall." Photo / AP
Co-pilot Mike Alsbury died in the explosion over the Mojave Desert. Photo / AP
Witnesses reported seeing Siebold descending with part of the base of his seat still attached. It is likely that his oxygen mask, attached to a portable tank, remained in place. But at that altitude, the sudden decompression and extreme G-forces would have caused him to black out in seconds.
His emergency parachute deployed at around 20,000ft. It is not known if he pulled the cord or if it unfurled automatically. Both pilots were wearing parachutes calibrated to open automatically at a certain height in the event they became unconscious during an emergency.
Dr Siebold, 79, explained: "He doesn't know how he managed to exit SpaceShipTwo. They don't have an ejection seat. They have a panel they take out and they have to crawl towards the hole and jump out. But the plane broke up suddenly. I'm sure he was unconscious because he could not have maintained consciousness at 50,000ft.
"He doesn't remember anything from the actual crash. He came to during the descent. He must have woken up about halfway down. When he was on the way down the chase plane was circling him and he was waving and giving the thumbs-up to indicate he was all right while he was dangling from the parachute.
"He's recovering at home. He broke the head of the humerus bone that sits in the right shoulder. He's got a rib and lung contusion and there is an issue with his eyes because of the cold. It was around minus 60 degrees up there.
"It's a medical miracle he survived considering the temperature, the lack of oxygen and the barotrauma [injury caused by a sudden change in pressure].' The pilot's horrified wife, Traci, and children 12-year-old Alexandra and Nick, nine, were standing with the family of Mike Alsbury as the tragedy unfolded.
Wreckage of the Virgin Galactic spacecraft. It separated mid-air. Photo / AP
The body of Alsbury, 39, was found still strapped into his seat on a desert road by construction workers. His parachute did not deploy. His wife Michelle said she had "lost the love of my life".
Dr Siebold said: "Mike's children and my grandchildren were all watching the flight so the emotional impact of that is tremendous.
"Mike was a friend and neighbour. Their children are the same age and friends. Peter is asking himself whether he could have done more and why he got out and Mike didn't? Traci is a strong woman. She's drained but very much in charge.
"She's protecting Peter and she's holding up incredibly well most of the time. He's on pain medication, which is making him tired and confused."
Never worried
Dr Siebold, who split with Peter's mother Barbara when his son was five, spoke proudly of teaching his son to fly: "Flying was the only thing Peter was ever really interested in. I flew privately - that was my recreation - so he grew up with it. It's what we did together. We would go to the airport after school."
At 16, Siebold studied aviation at California State University and landed a job with Scaled Composites - the company conducting last week's test flight for Virgin Galactic - before he graduated.
"He worked as an engineer and pilot, starting from the bottom and working his way up," Dr Siebold said proudly.
Siebold began working as a test pilot and engineer with Virgin Galactic at the start of its space programme a decade ago.
Richard Branson is under pressure to mothball his space programme. Photo / AP
"He told me straight away he was involved with Virgin Galactic," his father continued. "Safety was a great concern but I had total confidence in his piloting skills.
"Peter would say, 'These airplanes fly just beautifully.'
"He was never worried about the safety aspect of it."
The October 31 flight was so routine that Dr Siebold had no idea his son was piloting the pioneering craft that day until his panicked daughter-in-law phoned: "I picked up the phone oblivious to what had happened. I said, 'Hi Traci, how are you?' cheerful as usual and she said, 'It's serious. Peter had an accident. We don't know exactly but it looks like he hurt his shoulder and he's on his way to the hospital.'
"We were worried but the main thing was we knew he was alive. I hope he's going to recover enough to be able to fly again. That's his life. We're focusing hour to hour rather than day to day."
Yesterday, it was revealed that 24 passengers who have paid £157,000 each for the chance to go into space - alongside celebrities including Angelina Jolie and Kate Winslet - have demanded their money back.
Virgin Galactic chief executive George Whitesides claimed it was "unsurprising" passengers had pulled out, adding: "I think what is relevant is that the vast majority have said, 'Don't give up, keep going, we're with you.'"
Before the accident, billionaire Sir Richard Branson vowed he and son Sam would become astronauts by the end of this year and the first space tourist flights would begin next spring. But the Virgin Galactic project has been beset by years of delays and safety fears, including previous accidents with SpaceShipOne which necessitated a redesign of the ship's engines and fuel.
The investigation into this month's crash is now likely to delay any commercial flight for at least another year. But Branson has vowed to press ahead with the project, while acknowledging the risks taken by his test pilots.
Last night, Mr Whitesides paid tribute to Siebold, saying: "It will be regarded as one of the most amazing test flight survival stories of all time."
