SpaceShipTwo, the craft in which Virgin Galactic hopes to fly more than 370 paying space tourists to suborbital altitudes, made its first solo unpowered flight on 10 October – in a flight test designed to assess its performance when returning to Earth.
Slung between the twin fuselages of the carbon-fibre, four-engined WhiteKnightTwo mothership, SpaceShipTwo – named the VSS Enterprise – was carried to an altitude of 13.7 kilometres (45,000 feet). Then, using a novel release mechanism developed by Mojave, California based Scaled Composites, the maker of both the aircraft and the spacecraft, SpaceShipTwo was released to fly alone for the first time.
Much post-flight analysis remains to be performed, but Virgin and Scaled Composites say the release mechanism, handling, and flight controls appear to have worked as they were designed and simulated to.
“The VSS Enterprise was a real joy to fly,” reports Peter Siebold, one of yesterday’s test pilots and a veteran of the the Ansari X-Prize winning SpaceShipOne campaign. “Especially when one considers the fact that the vehicle has been designed not only to be a Mach 3.5 spaceship capable of going into space but also one of the worlds highest altitude gliders.”
Further tests need to be done before the paying public can venture aboard, however, and they will be riskier.
In an actual suborbital space shot, SpaceShipTwo will be released, point its nose upward and then fire its novel hybrid rocket motor when it’s clear of WhiteKnightTwo. Reaching speeds of 3.5 times the speed of sound, it will soar to a target suborbital altitude of 100 kilometres, as did its much smaller predecessor, SpaceShipOne.
The motor is dubbed a hybrid because it burns both gaseous and solid propellants: nitrous oxide gas ferociously oxidises a solid rubber-like fuel. But no-one has built a such a large hybrid rocket before – and a major accident highlighted the risks in 2007.
George Whitesides, until recently chief of staff at NASA, and now CEO of Virgin Galactic, says: “Our challenge going forward will be to complete our experimental program, obtain our Federal Aviation Administration licence and safely bring the system into service at Spaceport America in New Mexico.”
On the ground, things are moving fast, too: an inauguration ceremony for the Spaceport America runway is due to be held on October 22.