Virgin Galactic has unveiled a new private spaceship design for human flight this week.

The White Knight Two (WK2) aircraft carrier, in Mojave, Calif., is about 60% complete and is on track for flight tests this summer, the company said.

The carrier's launch system is based on the technology of SpaceShipOne, which flew into space three times and won a $10 million Ansari X Prize. Virgin Galactic said the launch system is "environmentally benign" and the spaceship is the world's largest, all carbon composite aircraft.

The company said it created a unique high-altitude lift capacity with four Pratt and Whitney PW308A engines to launch SpaceShipTwo, eight astronauts, and additional payload -- like small satellites and scientific equipment -- into sub-orbital spaceflight.

"While the first priority for Virgin Galactic is developing the market for human spaceflight, the company is already assessing the potential for unmanned launch capability," Virgin Galactic said in a statement released Wednesday.

Burt Rutan, CEO of Scaled Composites, said his company produced "a safe but flexible design capable of multiple applications in new market sectors."

"Looking up -- way up!" is an expression we have shared since the X Prize began and now we are all excited that this year the dream will start to become a very tangible reality for everyone involved," he said in a prepared statement.

Virgin Galactic counts more than 200 future astronauts and about 85,000 "registrations of interest" to fly. Eighty of SpaceShipTwo's first passengers have completed medical assessment and centrifuge training at the NASTAR facility in Philadelphia. Participants in G Force training withstood spinning at high speeds to simulate suborbital flight conditions.

Virgin Galactic also publicly displayed the final design for Spaceport America, in New Mexico this week. The company boasts that the spaceport will be the world's first custom-designed, private spaceport. The port will use geo-thermal, solar, and wind power to minimize its carbon footprint, Virgin Galactic said.

Sir Richard Branson, founder of Virgin Galactic, said his company will work with Pratt and Whitney and Virgin Fuels to test bio-fuel for the PW308A engines.