British tycoon Richard Branson has insisted his dream of commercial space travel remains alive.
But he warned his Virgin company would not "press on blindly" without knowing what caused the spacecraft crash that killed one pilot and seriously injured another in a Californian test flight.
Virgin Galactic's SpaceShipTwo rocket came down in the Mojave Desert yesterday.
Speaking this afternoon after arriving in the California facility which had been the hub of Virgin Galactic's ambitious space programme, he said any would-be astronauts who had paid the €200,000 cost of a seat would get a refund if they wanted one.
But he added: "We would love to finish what we started some years ago and I think pretty well all our astronauts would love us to finish and would love to go into space.
"I think millions of people in the world would one day love the chance to go to space and this is the start of a long programme."
Mr Branson said safety remained his paramount concern.
All our thoughts are with the brave pilots & families affected by today's events in Mojave http://t.co/kJGG0NQTNf @VirginGalactic
— Richard Branson (@richardbranson) November 1, 2014
His comments at the Mojave Air and Space Port came as a team of federal investigators began probing the causes of the accident, which dealt a devastating setback to the cause of commercial space tourism.
"We owe it to our test pilots to find out exactly what went wrong, and once we've found out what went wrong, if we can overcome it, we'll make absolutely certain that the dream lives on," Mr Branson said.
"We do understand the risks involved, and we're not going to push on blindly. To do so would be an insult to all those affected by this tragedy.
"We're going to learn from what went wrong, discover how we can improve safety and performance and then move forward together," he said, adding they were working with authorities in the investigation.
"We've been undertaking a comprehensive testing programme for many years and safety has always been our number one priority," Mr Branson said, before leaving for a meeting with grieving Virgin Galactic staff.
National Transportation Safety Board (NTSB) acting chairman Christopher Hart said investigators were entering unknown territory but hoped to find clues to the accident in data gathered by Virgin Galactic.
It was not immediately known if a black box flight data recorder was installed on the doomed suborbital craft, Mr Hart said.
"This was a test flight and test flights are typically very well documented in terms of data," he said. "And we may get some video feed. We may have lots of evidence that will help us with the investigative process."
SpaceShipTwo has been under development at the Mojave Air and Space Port.
It was designed to be carried into the air by the WhiteKnightTwo jet and then released before igniting its rocket to travel into space, and then returning to Earth as a glider.
The flight had taken off at 9.30am local time (4.30pm Irish time yesterday) and the two craft had separated at 10.10am (5.10pm Irish time yesterday).
A problem was discovered two minutes later and teams were sent to the crash site 40km north of the local airport.
Virgin Galactic has been the frontrunner in the race to send paying customers into space and Mr Branson said last month that he hoped to travel with his son on the first flight next spring.
Seats have been sold for more than €200,000 with full payment due at the time of booking.
The company said customers have visited Mr Branson's Caribbean home, Necker Island, and experienced G-force training.
Physicist Stephen Hawking, singer Justin Bieber, comedian Russell Brand and actor Ashton Kutcher are among the celebrities who have already signed up for flights.
Mr Branson said he was determined to help authorities find out what caused the crash but likened the incident to the early days of flight.
He said: "In the early days of aviation there were incidents and then aviation became very safe.
"In the early days of commercial space travel there have been incidents and then, we hope, that one day the tests pilots will enable people to go into space safely and that is our wish and desire."
The Virgin tycoon said the company had had numerous messages of support, including one new sign-up to the programme yesterday.
"I think that they (astronauts) have been patient to date, I think most of them will be patient longer," he added.
"We may lose one or two but it does not look like it. Anybody whoever wants a refund would be able to get a refund. We haven't used the money."
He also hit out at people who have been commenting on possible causes of the incident, adding: "I find it slightly irresponsible that people who know nothing about what they are saying can be saying things before the NTSB makes their comments."
