The investigation into what caused the Virgin Galactic test flight to crash could take as long as 12 months, lead investigator Chris Hart has said.
Mr Hart, who is acting head of the National Transportation Safety Board, also told reporters that his team would interview injured co-pilot Peter Siebold when he was ready.
Sir Richard Branson said he had never met the pilot who died in yesterday's test flight, but confirmed he worked for Virgin Galactic's partner Scaled Composites and said everyone's thoughts were with their families.
Sir Richard said he and his Virgin Galactic colleagues were "determined to find what went wrong" in the SpaceShipTwo crash and would be working with authorities investigating the crash.
"We have always known commercial space travel is incredibly hard," he said, adding that "safety has always been our number one priority" during a programme he described as the "biggest test programme in commercial aviation authority".
Faced with a five-mile debris trail and masses of technical data, the team investigating the crash of SpaceShipTwo have their work cut out.
The loss is a tragedy for this small tight-knit team that dreams of making the trip into space accessible to travellers not just astronauts.