ASCENT TO ORBIT

aAny journey from Earth begins with ascent to orbit.  This climb out of Earth's gravity well is the most costly and difficult part of a voyage into space.  A Space Shuttle launch costs $400-500 million.  Originally, it was planned to cost only $15 million.  Our future progress in space hinges on the development of a low cost rocket for transporation to Earth orbit.

How do we go beyond LEO?  We can build all sorts of spaceships, but what about fuel?  The cost of launching fuel to orbit is enormous.  We could send a probe to an asteroid, detonate a nuclear bomb and divert the asteroid into Earth orbit, then mine the giant rock for fuel, but what if there is a malfunction and the asteroid slams into the Earth?  Can we really dare take that chance?  Fortunately, there are ways to surmount this challenge.  The Moon could supply hydrogen and oxygen from easily mined ice in permanently shadowed polar craters.  After  industry is established on the Moon, rockets could be fueled with aluminum and oxygen.  Magnesium, which boils at only 2000 F. could be used as reaction mass in electric drives and uranium for spaceship reactors could be mined on the Moon. Cycling stations could travel between LEO and the L2 region 40,000 miles beyond the Moon with just an occasional use of rocket power to make course corrections.  Cycling stations can also cycle between Earth and Mars.  Solar sails and magnetic sails don't need any propellant and these could be used to haul cargos around in the inner solar system.  Spaceships leaving Lagrange points in the Earth-Moon system could obtain gravity assists during flyby past the Earth and Moon and pick up speed for free.  For lunar tourism, cycling stations and "taxis" fueled with lunar aluminum and LOX will be the way to transport large numbers of tourists in the future.  Eventually, space supertankers using solar and magnetic sails will haul hydrogen in from asteroids that will be combined with lunar liquid oxygen or LUNOX for rocket propulsion.

In orbit, at least 100 miles high, at 17,600 mph, we are "halfway to anywhere."

Have rocket, will travel.  Aside from far-out things like space elevators, high thrust rockets are the only way to reach orbit.  Once you are there various exotic technologies like cycling stations, sails and ion drives are the way to go.