Sir Richard Branson takes off on 'extraordinary' space flight

UK businessman Sir Richard Branson is on his way to fulfilling a lifetime's ambition: flying to the edge of space.

His Virgin Galactic rocket plane has taken off for a 1.5-hour mission which will see it reach an altitude where the sky turns black and the Earth's horizon curves away into the distance.

The entrepreneur says he wants to evaluate the experience before allowing paying customers aboard next year.

The mission above New Mexico began shortly after 08:30 EST (15:30 BST).

The vehicle, known as Unity, will be carried by a much bigger aeroplane to an altitude of about 15km (50,000ft), where it will be released.

A rocket motor in the back of Unity will then ignite and blast the ship skyward. The motor will burn for 60 seconds, by which time Sir Richard, his three crewmates and the two pilots up front, will have a remarkable view of the planet below.

The maximum height achievable by Unity is roughly 90km (55 miles, or 295,000ft), but towards the top of the climb Sir Richard will start to enjoy a few minutes of weightlessness and he'll be able to float around the cabin and to look out of the window.

Eventually, though, he'll have to strap back into his seat for the glide return to the spaceport in New Mexico.

Sir Richard will be taking instruction throughout the flight from Beth Moses. She's the chief astronaut instructor at the businessman's Virgin Galactic company. Apart from the firm's cadre of test pilots, Moses is the only person who's so far experienced the exhilaration of an ascent. The view out of the window, she says, is "just phenomenal".

"Pictures don't do it justice. It's just so bright and beautiful. I saw the ocean, and halfway up the US and halfway down into Mexico. I saw the green of the land and the white snow-capped mountains," she told BBC News.

"Because you are weightless and still, and the ship has come to a stop, you can just soak it in, in a really timeless way. It stuck in my soul."