The first landing of a Virgin Galactic SpaceShipTwo-class vehicle on 10 October at the Mojave Air and Space Port marked a key milestone in the growth of commercial spaceflight.
After release from the mothership Eve at an altitude of 45,000ft (13,720m), the series of test points completed as VSS Enterprise glided to a landing are no doubt critical, but pale in significance to the symbolism of the moment.
For close observers of the unlikely commercial spaceship factory deep in the California desert, the landing of the Enterprise flashed in one moment a six-year, six-day day journey since the final flight of record-breaking SpaceShipOne.
“For the first time since we seriously began the project in 2004, I watched the world’s first manned commercial spaceship landing on the runway,” says Virgin Galactic founder Sir Richard Branson, “and it was a great moment.
The programme has so far overcome the tragedy of a rocket oxider coldflow test accident in 2007 that killed three workers, which resulted in a set of safety guidelines that Scaled Composites published in hopes of reducing the risk of handling nitrous oxide.
More recently, the WhiteKnightTwo-class mothership faced what Virgin Galactic called a “very, very minor incident” when the left main landing gear collapsed on 19 August. It was the 37th test flight of the Eve vehicle, but the damaged was repaired within weeks.
Overall, the Eve has now flown 40 times since completing its maiden flight in December 2008. The mothership has flown with the Enterprise attached to the mid-point of its arched wings on four flight tests.
In the next year, Scaled Composites, the designer and builder of Virgin Galactic’s hardware, will push the hybrid rocket-powered, six-passenger SpaceShipTwo to repeat and surpass the Ansari X Prize triumph of its smaller predecessor, SpaceShipOne – soaring at M3.5-speed to 110km (68 miles) over the Earth’s surface, then deploying the feathered re-entry system to decelerate while gliding through the atmosphere to landing.
The first glide test – notably completed on 10/10/10 – gave pilot Pete Siebold and co-pilot Mike Alsbury their first idea of how the aircraft will behave on its critical descent profile.
In an 11min glide from altitude, the Enterprise opened two-thirds of the SpaceShipTwo subsonic speed envelope, manoeuvred beyond 2g and checked out stall characteristics, says Burt Rutan, Scaled Composites’ founder and chief technical officer.
Rutan credited SpaceShipTwo configuration and aerodynamic designer Jim Tighe for getting it “right out of the box” and exceeding pre-flight predictions of the aircraft’s handling and responses to control.
With flight controls, landing gear, electrical and pneumatic systems recording a “flawless” first flight, Rutan says, the need for “tweaking” the aircraft will not be significant.
“We can move forward with the testing without major modifications,” Rutan says.
Despite gaining experience on SpaceShipOne in 2004, the changes made to SpaceShipTwo – including a shift from a mid- to a low-wing, stretched cabin and new rocket thruster – made surprises possible in flight test.
By late 2011, the SpaceShipTwo is widely expected to begin its flights into space, a first for a spacecraft designed for commercial purposes. More than 300 depositors committed to take a $200,000, 2.5h-ride into space await the conclusion of the flight-test process.
Rutan has revealed a vision for offering suborbital space trips for thousands of people using a fleet of hundreds of SpaceShipTwos and at least dozens of motherships, all operating from a Virgin Galactic spaceport being christened in New Mexico on 22 October.
“Now our challenge going forward,” says Whitehorn, “will be to complete our experimental programme, obtain our Federal Aviation Administration licence and safely bring the system into service at Spaceport America, New Mexico.”