Sixteen months after a fatal test flight destroyed its first spaceship, Virgin Galactic on Friday unveiled its gleaming new SpaceShipTwo, named "Unity" by British physicist Stephen Hawking, one of nearly 700 people signed up for rides.
"I never thought I'd have the opportunity to see our beautiful planet from space or gaze outward into the infinity beyond. This was domain of astronauts, the lucky few," Hawking said during a recorded message broadcast during Unity's unveiling at the Mojave Air and Space Port in Mojave, Calif.
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Virgin Galactic founder Richard Branson previously invited Hawking to fly aboard SpaceShipTwo, an offer Hawking said he plans to accept.
"If I am able to go and if Richard will still take me I will be proud to fly on this spaceship," Hawking said.
"We are entering a new space age and I hope this will help to create a new unity. Space exploration has already been a great unifier. We seem to be able to cooperate between nations in space in way that a way we can only envy on Earth.
"Taking more and more passengers out into space will enable them and us to look both outwards and back, but with a fresh perspective in both directions. It will help bring new meaning to our place on Earth and to our responsibilities as its stewards. And it will help us to recognize our place and our future in the cosmos, which is where I believe our ultimate destiny lies," Hawking said.
The spaceship was then christened with a bottle of milk -- a nod to Branson's granddaughter who celebrated her first birthday on Friday. Another Galactic customer, British singer Sarah Brightman, led the crowd in singing "Happy Birthday."
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"I hope this is not going to cause a problem trying to match this for future birthday parties," Branson quipped.
From the outside, the new spaceship resembles the fleet leader, which broke apart over Mojave, California, on Oct. 31, 2014, during its fourth powered test flight. Co-pilot Michael Alsbury, who worked for SpaceShipTwo designer and manufacturer Scaled Composites, was killed in the accident. Pilot Pete Siebold managed to parachute to safety.
Virgin Galactic had already had taken over manufacturing and testing of future ships, a plan that was accelerated after the accident, Will Pomerantz, vice president of special projects, told Discovery News.
The pieces for the second spaceship actually were more than 75 percent complete at the time of the accident, which may have helped Virgin Galactic's investors stay committed to the program, said Doug Shane, who oversees Galactic's manufacturing arm, The Spaceship Company, or TSC.
The new spaceship includes dozens of upgrades, some planned before the accident to ease commercial operations and reduce costs, some added as a result of the accident investigation.
The National Transportation Safety Board determined that Alsbury, a very experienced pilot, prematurely released a lever that was keeping the spaceship's rotating tail section from pivoting forward. That allowed the tail section, known as the feather, to rotate forward, before aerodynamic forces had built up to naturally hold it back. The feather, an invention of Scaled's founder Burt Rutan, is intended to ease the ship's re-entry into the atmosphere by changing its shape, allowing it to fall like a badminton shuttlecock.
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The co-pilot was supposed to unlock the feather when the ship was traveling at about Mach 1.4, the idea being that if the lock failed and the tail couldn't be rotated, pilots could abort the flight before the vehicle reached space.
Investigators found many contributing factors for Alsbury's error, all of which have been addressed by Virgin Galactic and reviewed by a panel of outside experts, Mike Moses, a former space shuttle program manager who now oversees spaceflight operations for Virgin Galactic.
The new SpaceShipTwo now includes a feather locking pin, controlled by the ship's flight computer, which prohibits pilots from unlocking the tail section early.
"One of the reasons why Scaled didn't do that in the first place is drove to a simplicity of design," Moses said. "Anything you put into place to stop you from doing something now can fail and stop you from doing what you really wanted."
Pilots will have a mechanical override if the locking pin fails, Moses added.
Also, because a new analysis showed the ship likely could survive re-entry with the tail section down, Galactic also decided keep the feather locked until after the ship's rocket engine had shut down. Pilots will have three- to five minutes to troubleshoot in case of problems before the feather would be needed for re-entry, Moses said.
Managers and engineers also used the accident to see if there were other systems or processes vulnerable to human error. Several minor changes were made, such as another locking pin to prevent a pilot from deploying the landing gear at the wrong time. Galactic also changed several switches to better differentiate them.
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"The question is ‘How can you prevent human error from causing a problem?' Moses said. "We didn't find any other fundamental things that had to change. We found a few things we could make better."
Friday's rollout in Mojave, California, marks the beginning of a new phase for Galactic, which plans to fairly rapidly build back up to where the original SpaceShipTwo was in its test flight program, and then continue testing until the ship is ready to enter commercial service.
Galactic declined to discuss timelines for when it will allow paying passengers to fly. The company has nearly 700 customers awaiting flights.
"I think they're going to make pretty rapid progress once they start flying," Galactic chief executive George Whitesides told Discovery News.