Musk has estimated that Dragon could be ready to begin crew-carrying operations within three years. SpaceX is also developing a heavy-lift rocket and hopes to devise a completely reusable launch vehicle as well, with the ultimate goal of helping humanity colonize other worlds such as Mars.
Virgin Galactic plans to launch paying customers on suborbital jaunts, and it has already collected deposits from more than 500 people willing to pay the $200,000 ticket price. The company also has inked deals to fly scientists and their experiments to suborbital space.
Virgin Galactic's SpaceShipTwo vehicle will launch to space after being carried about 50,000 feet (15,000 meters) above Earth's surface by a mothership known as WhiteKnightTwo. SpaceShipTwo has already made a series of glide flights, and the company is aiming for its first rocket-powered test flight by the end of the year. Commercial operations could begin in 2013 or 2014, officials have said.
Microsoft co-founder Paul Allen announced another air-launched space effort this past December. Allen, who is worth $14.2 billion, founded Stratolaunch Systems with renowned aerospace engineer Burt Rutan.