The Illustration that Inspired "Power Tower"
In his 1990 Ad Astra article Power Tower, Alan Wasser was the first to propose that the North or South Pole of the Moon would be the ideal location to set up a Power Tower for lunar solar power generation. All other locations on the Moon are subject to two weeks of darkness for every two weeks of sunlight. The poles themselves experience perpetual sunlight.
Below, Alan recounts the story of how the Power Tower idea came about.
Northern Norway - Land of the Midnight Sun
This 360-degree panorama shows the sun's cycle north of the Arctic Circle, photographed on the Island of Loppa from July 21, 19:00 hours, until July 22, 18:00 hours.
Origin of the "Power Tower" Concept
"When I first proposed the idea of using lunar real estate as an economic incentive for private space settlement, in 1988, I ran into objections along the lines of: "All parts of the Moon are identical, so why would anyone want to pay to own any particular piece?"
In 1989 I took the family on a trip to Scandinavia, and while there I saw this terrific illustration of just what "Land of the Midnight Sun" really meant. It is a series of 24 pictures of the sun, taken one every hour, from the same place. Suddenly, it "dawned" on me that the same phenomena would occur at the Moon's poles - but without the dimming effect of a long, oblique passage through the Earth's atmosphere.
Until then, everybody assumed that human landings would always take place near the lunar equator, because that's the easiest place to get to, and the easiest to see from the Earth. But I realized the "Midnight Sun" effect at the poles would solve one of the worst problems of lunar settlements at the equator, the 14 day long lunar night and its devastating effect on the use of solar power.
So, when I got home I started work on the Power Tower article. I got permission to use the Norway Sun illustration in the article, although the editor chose to use the less communicative version, without the clock faces as shown above, for some reason I never understood.