Last month, Virgin Galactic, a private space tourism company, unveiled the new version of its SpaceShipTwo vehicle. Dubbed the VSS Unity, it’s the spacecraft that will hopefully send paying customers into sub-orbital space someday.
“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,” said Virgin Galactic CEO Richard Branson. “Our beautiful new spaceship, VSS Unity, is the embodiment of that goal and also a great testament to what can be achieved when true teamwork, great skill, and deep pride are combined with a common purpose.”
Currently, over 700 people have reserved a flight on the spaceplane — each paying $250,000 a seat. However, before their customers can ride, Virgin Galactic has to prove it has a safe vehicle. According to the company, the first test flights of the new vehicle should begin later this year. The tests will determine whether or not the vehicle is capable of safely performing the maneuvers to get to sub-orbital space.
The VSS Unity is a replacement for Virgin Galactic’s first spaceplane, the VSS Enterprise, which crashed during a test flight in 2014, killing one pilot and severely injuring the other. An investigation by the NTSB following the accident ruled that the accident was partly due to pilot error.
Learning from their past mistakes, Virgin Galactic has altered the design of the VSS Unity to make it more autonomous. To fix the error of its predecessor, the VSS Unity was engineered with fail-safes in places to better protect pilots from making critical in-flight mistakes. The vehicle’s rocket engine will also be powered by a different rubber-like fuel. The new fuel has been known to cause issues, but will provide a more efficient combustion.
The VSS Unity is designed to take two pilots and six passengers up to the edge of space. Rather than launching the vehicle on top of a rocket, it is carried to an altitude of approximately 50,000 feet by a carrier aircraft called the WhiteKnightTwo. The WhiteKnightTwo looks like two different planes joined by a bridge in between. Outfitted with four engines and two main cabins, the VSS Unity will be secured underneath the bridge until it reaches launching altitude.
Once the vehicle reaches 50,000 feet, SpaceShipTwo will deploy, and its rocket engine will ignite, propelling the spacecraft to a speed of Mach 3.4 (roughly 2,600 miles per hour). The engine will only fire for 70 seconds, allowing the vehicle to coast up to an altitude of 70 miles above the Earth’s surface. At this vantage point, the passengers will be just 8 miles of the Karman line — the invisible boundary line that separates Earth’s atmosphere from outer space.
In order for the VSS Unity to re-enter Earth’s atmosphere, it repositions its wings as part of a maneuver called feathering. Just as the vehicle reaches peak altitude, the pilots have to pull two levers that move the wings from a horizontal position to an upright angle of 65-degrees. Feathering is crucial for slowing the vehicle’s descent–after the wings shift back to their horizontal position, the spaceplane can glide to a runway.
The feathering system is crucial for a safe descent and is also partly to blame for the 2014 accident due to Co-pilot Michael Alsbury unlocking the system too early. The vehicle was traveling at Mach 0.92 instead of Mach 1.4. It doesn’t sound like much of a difference, but given that the forces around the aircraft vary at different speeds, the forces associated with a Mach 0.92 speed overwhelmed the feathering system’s motor. The wings shifted on their own, causing strong G-forces to stress the vehicle. As a result, it broke apart.
Virgin Galactic has improved the feathering system on the new vehicle, ensuring that pilots will not be able to unlock it prematurely.
The spaceplane’s name, Unity, was chosen by the world-renowned physicist Stephen Hawking. “Space exploration is a great unifier,” Hawking said. “We seem to be able to cooperate between nations in space in a way we can only envy here on Earth.”
Hawking went on to say he would be proud to fly on board, and he will be watching over the vehicle–which wasn’t just hyperbole. His eye is painted on the side of the plane.