9. Summary of Issues Identified


 
 

During the course of this project, some special issues were identified, which went too far outside what we had the resources to study. These are discussed below.
 

9.1 Metal production on the Moon
 

As discussed in Chapters 5 and 6, the development of a Space-based economy is part of the process to create the demand, which will make large-scale construction in Space relevant. One of the primary barriers to such development is the difficulty of estimating costs and risks of any such project. In this environment, a reasonable calculation of the return on investment becomes too difficult to develop, to the thoroughness required to present to investors. While this sounds mundane, it nevertheless makes all the difference between a systematic approach, and Darwinian evolution.

Surprising to us, but probably well-known to others who have gone before us - but buried in some report of long ago, was the finding that the cost of steel manufacture on the Moon was perhaps the most uncertain of all the costs in the development of the 2km-dia cylindrical radiation shield. The reason for this is that steel manufacture by usual processes requires hydrogen and carbon in substantial quantities - and neither has been found on the Moon. The cost of delivering each from Earth is highly uncertain. Previous efforts to estimate the cost has made highly conservative assumptions, such as the assumption that the marginal cost of delivering a pound of hydrogen or carbon to the Moon, as part of a massive delivery operation, is the same as that of construction, per lb, of a completed Space Station.

 

In the case of hydrogen, this ignores the equally high cost of water on the Moon - and the opportunity to sell off the water to other users in a synergistic development, thus recovering the shipping cost of hydrogen. The alternatives are:

 
1. Recover the hydrogen from the water using an ISRU (in situ resource utilization) purification and electrolysis unit. In this case, the cost of steel becomes critically dependent on the efficiency of this unit in recovering the hydrogen for re-use. Thus one critical need is for high-efficiency, low-cost solar-powered electrolysis units. We expect that these will be developed as part of the Mars exploration effort, since shipping costs to Mars are even higher, and sunlight is scarcer there.
 
2. Steel manufacture from ore using intense solar-generate heating and/or electric fields. Again, there is considerable research done in this field, which must be taken through costing.


In the case of carbon, the best alternative may be to substitute carbon with silicon in steel manufacture. Again, this is an area where some research has been performed, and perhaps this should be combined with the research on lunar production of pure silicon for solar-cell applications. Reducing the uncertainty in the cost of metal production would go a long way towards developing a credible costing structure.

 

9.2 Resonator / waveguide technology

This was the other area where our exploration reached a canyon of our ignorance, too deep and wide for us to bridge without outside help and substantial learning. We were somewhat surprised to find, in July, that experts who had reviewed our proposal had in fact NOT laughed off the extreme idea of building spaceships and habitats out of pulverized asteroids using electromagnetic waves - but were getting disappointed that we were spending our time studying the more mundane things such as building 2km diameter radiation shields near the Moon. Following this eye-opener, we surprised ourselves at how far we were able to reach in proving the feasibility of radio-wave Tailored Force Fields - to build large radiation shields out of pulverized asteroids. We used prior demonstrations on Earth (the Arecibo SETI transmission) as proof that the required power levels were achievable. We also showed that resonators have been used to obtain extremely high microwave power levels. However, to go beyond this stage in designing resonators, amplifiers and antennae suitable for Space-based construction, we need expert help. This is an exciting field of endeavor - the possibilities are truly endless. It must be left to Phase 2.

 

9.3 Cost linkage to comprehensive plan

As indicated by the above items, the ability to do costing is critical to answering the "feasibility" questions and to plan really large steps. This was perhaps not the case in the 1940s and '50s, because the arguments that adequate tools were unavailable, and that hostile nations were racing towards similar objectives, were adequate to drive fast progress. However, today the public expects it. Thus a substantial effort in driving towards the TFF technological goals must be spent on developing cost, identifying technology options using cost considerations among others, and selecting the most effective path. This becomes critical because of the realization that only a synergistic effort involving many diverse projects and interests, can lead to such progress in a reasonable time.

 

9.4 The Microwave Demonstrator experiment

A major outcome of our study is that it is now possible to link phenomena across the acoustic, optical, microwave and radio wave domains of wave phenomena. For various reasons, discussed in the Phase 2 proposal, the microwave regime is the ideal one for an initial Space demonstration of construction in Space using electromagnetic fields. The technology for developing high-power microwave transmitters with excellent beam control is receiving considerable attention in the literaure. A recent example is Shaposhnikov [54].

 



Abstract 
Intro
Theory
Near-term: Acoustic
Mid-Term: L2 Habitat
Space Economy 
Far-Term: Radio-Wave Construction
Comments
Issues
Conclusions
Acknowledgements
References