In the May 3 issue, O. Glenn Smith asks, “Can costs be reduced enough to stimulate enough demand to get to the very high launch rates?” [“Human Spaceflight is a Tough Business,” Commentary, page 19]. There are two potentially very high-rate markets: space tourism and space solar power.

Tourism is very sensitive to price at all levels, although rates can be very high (hundreds of thousands a year). We will get a better idea of where tourism can go when the suborbital vehicles start flying, possibly in a year or so.

Space solar power has a threshold, once it becomes competitive with any form of terrestrial energy — say, nuclear, which has lifetime plant costs of $20 billion or more — the market becomes very large very quickly. Again, launch rates can be very high. Supplying 10 percent of current energy demand, making reasonable assumptions, would require about 75,000 launches of 50-ton payloads.

The key is a single profitable or near-profitable system that can be replicated. To do this with current launch constraints requires very lightweight systems, probably thin-film solar arrays. There is a lot of work on thin-film solar energy conversion for terrestrial use. Ideally, this work can be leveraged for space systems of very large thin-film solar arrays, perhaps using a heliogyro design to eliminate structural mass.

This one technical achievement, along with high-frequency power transmission to minimize antenna size, could enable a vast space solar power market. While the potential benefits are huge, current investment is near zero. Perhaps we should change that.


Al Globus

, Calif.