A few comments by Jim Benson from SpaceDev made me realize I hadn’t mentioned the propulsion prospects for SpaceShipOne. I think Scaled is considering a hybrid rocket engine, which uses a combination of solid and liquid fuel techniques. Specifically, they’re using a rubber solid fuel and nitrous oxide liquid oxidizer.
SpaceDev, one of the companies competing to provide the rocket, is a local (San Diego) company I’ve been admiring from afar for a while. With government-funded spaceflight facing a hostile climate, it’s good to know that someone in the private sector is taking on the challenge.