Moon Base One – Base Camp

Note that my short story “Lasso the Moon” is now accessible online, also at:
Story List

My plan for a real Moon Base, affordable very soon, focuses on the Falcon V launch vehicle. With 10,000 kg to LEO, this vehicle will be able to orbit a system capable of soft landing 1000 kg on the Moon. I will detail in steps how this is adequate to establish a lightweight “Camp”, for initial residence on the Moon. One $ 37 Million launch vehicle to establish a long term camp for one or two inhabitants.

Start with power – Solar of course. One square meter of solar panel will receive 1360 watts of solar radiation at normal incidence. Solar cell efficiencies – with the best multijunction cells – now run over 40% and the developers expect to achieve >50%. I will assume only the 20% conversion achieved by by good, singe crystal Silicon cells in what follows (272 watts/m^2 output), but better results are already available. Standard Silicon cells are 200 microns thick and weigh about 500 grams per square meter. Silicon thinned to 50 microns can produce equal efficiency cells and it looks and feels like Stainless Steel “shim stock”. It is flexible, tough and hard to break except intentionally. It is strong enough to serve as a “tension web” in a mechanical structure which also includes lightweight ribs and spars. This thickness only weights 125 grams per square meter!

A 20 square meter panel of the thinned Silicon Cells (the size of a “carport” roof) could produce 5400 watts peak electrical power and have a total mass of 3 kilograms! This flimsy structure would be more than adequate in the benign environment of the Moon, and provide desirable shade in addition. This is a far cry from the 100 Watts/kg suggested in textbooks, but this is not for a “mechanism”. It must be hand assembled by astronauts standing on the Moon, although this needn't take over an hour.

The reality of >40% solar cell conversion efficiency (and > 1 kW/kg mass performance) completely rules out machinery to apply concentrated sunlight for heating! The mass and losses associated with tracking the sun, collecting the sunlight and feeding materials to be heated into the focus, greatly exceed the roughly 50% loss from conversion to electricity. Double the size of the solar panels – with modest added weight – and use precisely controlled electrical heating wherever you need it!

This is an encouraging data point (5400 Watts peak power from a 3 kg solar system), but is far from the complete story. Even averaging the power for the day / night cycle (1600 Watts average) still leaves a big problem. Storing power for the 14 period of darkness is a Very Big Problem! (Roughly 28 times the storage requirement of Solar Power on the Earth.) More soon.