Before humans can venture to live for extended periods in Space, the problem of building radiation shields must be solved. All current concepts for permanent radiation shields involve very large mass, and expensive and hazardous construction methods. In this project we consider how such massive structures will be assembled automatically, using at most telepresence or robotic control.
A unique set of experiments by our team had shown that by tailoring potential fields, large numbers of objects can be moved into desired positions and desired shapes can be constructed in reduced-gravity environments. Under this project, the promise of this idea was investigated for several types of force fields suitable for automated construction at levels ranging from micrometer-scale discs, to kilometer-scale habitats.
The theory for radiation force was generalized and applied to acoustic, optical and other electromagnetic fields. A sample case using silicon dioxide particles of various sizes was used to develop a direct comparison of the accelerations obtainable using different wavelengths of radiation.
The feasibility of building objects at the 0.1 m scale using acoustic fields had already been proven through reduced-gravity flight experiments. This was carried forward with experiments being developed for space-flight proof on the STS.
A concept for a 50m-scale shield built using radio waves was explored. Calculations show that with developments in extraterrestrial infrastructure, this offers strong potential as a construction technique for the future. Thus the primary obstacle to all of the ideas here is the development of an economic basis for extraterrestrial infrastructure. This was addressed by considering the architecture required to develop a suitable Space habitat in the middle term future.
Calculations show that in the 15 - 30yr time frame, a 2km diameter, 2km long cylindrical radiation shield can be built at the Earth-Moon L-2 Lagrangian point using lunar materials and solar-powered quasi-steady electromagnetic fields. The project architecture is aligned with proposals for various other elements of a Space-Based Economy, bringing project cost well within reason.