An analysis of alternate hydrogen sources for lunar manufacture

A limitation to the exploration and use of space for scientific and industrial enterprise is the high cost of energy needed to overcome the Earth's gravitational field in order to lift terrestrial materials into space. The reuseable space shuttle reduces the capital cost of ferrying such materials to near earth orbit but has little impact on the energy cost. The material requirements of servicing satellites in geosynchronous orbit and of exploring and colonizing the moon and nearby planets will be even more expensive in energy if all that material must be of terrestrial origin. One cost reducing alternative is to use materials already available in near Earth space, that is on the moon and on asteroids with earth approaching orbits.