Professor Stephen Hawking announced the world is "entering a new space age" as he helped to unveil the new Virgin Galactic SpaceShipTwo.
The new spaceplane was unveiled more than a year after a midair crash killed one pilot and left another seriously injured.
Despite the setback, Sir Richard Branson said that after some soul searching the company decided to push ahead with its vision of sending commercial passengers into space.
Prof Hawking, who suffers from the degenerative condition amyotrophic lateral sclerosis (ALS), confirmed that he is still hoping to take a trip into space on a Virgin Galactic rocket.
The astrophysicist, who attended the grand unveiling, said: "A man with the vision and persistence to open up space flight for ordinary, earth-bound citizens, Richard Branson made it his mission to make space flight a reality for those intrepid enough to venture beyond the boundaries of the earth's atmosphere.
"I have had ALS for over 50 years now and, while I have no fear of adventure, others do not always take the same view. If I am able to go - and if Richard will still take me, I would be very proud to fly on this spaceship.
"Space exploration has already been a great unifier - we seem able to cooperate between nations in space in a way we can only envy on earth. We are entering a new space age and I hope this will help to create a new unity."
Prof Hawking named the new vehicle Virgin Spaceship (VSS) Unity at the ceremony, which was attended by four generations of the Branson family.
Sir Richard's grandchild Eva Deia celebrated her first birthday by christening the spaceship with milk rather than the traditional bottle of champagne.
SpaceShipTwo is designed to take a crew of two pilots and up to six passengers to space. The flight experience will feature an air launch followed by a rocket-powered ascent at three and a half times the speed of sound, the silence of space, several minutes of out-of-seat weightlessness and views of earth.
Sir Richard said: "Together, we can make space accessible in a way that has only been dreamt of before now, and by doing so can bring positive change to life on earth.
"Our beautiful new spaceship, VSS Unity, is the embodiment of that goal and will provide us with an unprecedented body of experience which will in turn lay the foundations for Virgin Galactic's future.
"Her creation is also great testament to what can be achieved when true teamwork, great skill and deep pride are combined with a common purpose."
Virgin Galactic chief executive George Whitesides said: "We seek to open space to people from all walks of life, and today's milestone is a big step toward that goal. Outer space is the province of all humanity, and we think it is about time that all of humanity has a chance to explore it: not just pilots but also painters, not just engineers but also everyday explorers."