It uses a hybrid rocket motor powered by nitrous oxide and hydroxy-terminated polybutadiene (rubber), and is launched at altitude by a jet powered carrier aircraft called White Knight. The cabin has space for three people, including the pilot.
On December 17, 2003 (100 years to the day since the Wright Brothers made the first powered flight) it made its first powered flight, following several months of glide tests. During this first flight it achieved a speed of 930mph (Mach 1.2) and an altitude of 68,000 feet (20,725 m). This was the first supersonic flight by a non-publicly funded aircraft.