The National Aerospace Plane (NASP) was cutting-edge in its day. It started as a research project of the Defense Advanced Research Projects Agency. President Ronald Reagan announced the project to the public during his 1986 State of the Union address, calling it the “Orient Express.” Its engine was to be of a revolutionary scramjet design. This engine uses hydrogen as fuel, and unlike more common ramjet designs, scramjet internal combustion takes place at supersonic speeds. The NASP was expected to reach speeds up to Mach 20. The project was ultimately terminated due to budget cuts and the prototype X-30 never flew. But the plane lives on as a workable approach to a Single Stage To Orbit (SSTO) airplane, i.e. a plane that could take off from an ordinary runway and reach low earth orbit. A later development of the concept was the X-43: a small, unmanned vehicle that used a scramjet. During flight tests the X-43 reached a top speed of Mach 9.65 at 110,000 feet altitude in 2004. It looked very much like the NASP.
The earthship featured in Chapters 1 and 2 is based on the NASP. Its engines would be capable of multiple modes of operation: from turbojet on the runway, to scramjet at high speeds, and finally to rocket power in the upper atmosphere and the vacuum beyond. The earthship would surely expend all its fuel to reach orbit, but there’s a parallel idea of orbiting fuel depots. These floating gas stations would include a set of cryogenic tanks holding liquid hydrogen and oxygen. Once in low earth orbit, the earthship would attach to a depot, fuel up, and continue with a trans-lunar injection burn to travel to the Moon.
Love and Other Metals is now available as an on-demand paperback on Amazon at this link: http://www.amazon.com/dp/1520920962. I’ve also posted the second chapter of Human Enough. Have a look.