Sir Richard Branson says he is committed to his ambition of offering commercial flights into space, despite yesterday's Virgin Galactic crash.
A spacecraft came down during a test run in California yesterday, killing one pilot and badly injuring another.
The Virgin Group founder arrived in the Mojave Desert today, and has described the journey to the crash site as "one of the most difficult trips I have ever had to make".
In a post on his website, Sir Richard said: "Space is hard - but worth it. We will persevere and move forward together."
"All our thoughts are with the families of everyone affected by this tragic event, and we are doing everything we can to support them," he explained.
"We've always known that the road to space is extremely difficult - and that every new transportation system has to deal with bad days early in their history," he added.
One pilot died in the crash and another was seriously injured when he ejected from the rocket plane and parachuted to the ground.
Virgin Galactic, part of British billionaire Sir Richard's Virgin Group, had been aiming to begin tourist flights to the edge of space next year.
SpaceShipTwo has been under development at the Mojave Air and Spaceport.
The tragedy occurred after SpaceShipTwo fired up its rocket following a high-altitude drop from Virgin Galactic's WhiteKnightTwo mothership.
Stuart Witt, chief executive of the space port, said the cause of the crash remains unclear.
Virgin Galactic said it will work with authorities to determine the cause of the accident. The Federal Aviation Administration is also investigating.
It is the second disaster involving a US spacecraft this week.
On Tuesday, another private company's unmanned rocket exploded six seconds after launch on a resupply mission to the International Space Station.
Virgin Galactic's 60ft (18 metre) long SpaceShipTwo was testing a redesigned rocket motor as it made its first powered flight since January.
The rocket plane, which was attached to the underside of WhiteKnightTwo, took off at 9:19am local time on Friday in California.
It is not the first accident involving SpaceShipTwo.
During testing for the development of its rocket motor in July 2007, an explosion at the Mojave spaceport killed three workers and critically injured three others.
Virgin Galactic aims to become the world's first commercial "spaceline", sending customers willing to pay up to $250,000 (approx€200,000) for a short journey into zero gravity and a glimpse of the planet from the edge of space.
The company previously said it has accepted more than $80m (approx €64m) in deposits from hundreds of people who hope to be among the first space tourists.
British physicist Stephen Hawking, comedian Russell Brand, actors Leonardo DiCaprio and Ashton Kutcher, and singer Justin Bieber are said to have signed up.
