Businessman Richard Branson is re-launching his Virgin Galactic project to send passengers into space.

The venture suffered a setback in 2014, after one pilot was killed and another seriously injured in a crash on a test flight.

The venture is unveiling SpaceShipTwo - a six-passenger space plane which will take commercial customers on five-minute trips into suborbital space.

But the company says this is all still years away.

"If you are expecting SpaceShipTwo to blast off and head straight to space on the day we unveil her, let us disillusion you now: this will be a ground-based celebration," it says.

"Indeed, our new vehicle will remain on the ground for a while after her unveiling, as we run her through full-vehicle tests of her electrical systems and all of her moving parts".

"Once that is done, we'll be eager to get air under the wings of our new spaceship", it adds.

The firm says they will begin first with a captive carry flight - where the ship stays atop her mothership, WhiteKnightTwo.

They will then move to glide testing, where the new spaceship flies freely for the first time.

"Each flight will generally fly a little higher, a little faster, and sometimes we may need to repeat a test point to get additional data or confirm a result", it says.

Mr Branson says he hopes it will be affordable for everybody one day.