Detailed text transcripts for TV channel - CNN - 20181216:12:55:00
Motor. they're using kind of a rubber fuel, a solid fuel within an oxidizer that fuels over it. scaling it is a bit of an issue. spaceship one flew in 2003 and used the same kind of technology and everybody thought it would be a simple matter to make a bigger spaceship one. it's taken since 2003 until now and spaceship one flew into space, by everyone's definition, over 100 kilometers. and after all these years, after 11 years, spaceship two finally made it up almost that high. that shows you the difficulty and scale in both the vehicle and the rocket engine to make it. it probably won't be us...
Source: archive.org