First, I want to see a low cost way to get from ground to Low Earth Orbit (LEO). An air breathing first stage, lifting one or two rocket stages, might be a way to go. Or, maybe the British Skylon single stage air breather/rocket will work. Once in LEO, high thrust is not needed. Solar photovoltaic cell powered neutral particle beam rocket engines could provide extremely high specific impulses, allowing much shorter transit times via continual, albeit low, accelerations between LEO and points beyond. Alkali metals could be used as reaction mass, hauled from earth initially, but later, reaction masses could be mined from asteroids. Round trips to Mars could take months, or even weeks, instead of years. Solar sail type reflectors could be used as reflecting concentrators to provide increased sunlight to photovoltaic cells for particle beam rocket power on missions farther away from the sun. On Mars, manned outposts could be built; the high g forces needed to get back up from the surface could be provided by hydrogen/oxygen rockets powered by electolyzed water. Manned outposts on(or rather, under the surface of) the moon could also be built, with local materials used to supply reaction mass/fuel for rockets to return upwards from the moon. Or, maybe, an electromagnetic mass driver for return trips could be designed, on this airless bofdy. Nearer the earth, in higher, stable orbits, very, very large optical telescopes could be build in a zero g environment, and used to look for planets around nearby stars. It all depends, though, on getting past the critical ground to LEO cost problem.
Comments & Sharing
Let's Change the World
Become a member of The Planetary Society and together we will create the future of space exploration.