Engines of Our Ingenuity

No. 430:
MINING THE MOON

by John H. Lienhard

Click here for audio of Episode 430.

Today, the moon waits for us to expand our vision. The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

For 20 years I've wondered why we lost interest in the moon so quickly after we first walked on it. Maybe it was because we looked over the astronauts' shoulders and saw only a great slag heap. Now geologist Donald Burt asks if it's only that or more. Does the moon hold riches, or is it just a scabrous wasteland?

We know a lot about the moon today. It's rich in aluminum, calcium, iron, titanium, and magnesium. There's also plenty of oxygen on the moon, but it's all bound up in compounds that are hard to break down. You can get at it, but it'll take a lot of processing. Maybe we can pull some hydrogen and helium-3 out of the rocks as well.

What's absolutely missing on the moon is anything volatile. There's no water -- no loose gas or liquid of any kind. The vacuum on the moon is more perfect than any we've ever created on Earth.

So can we go after minerals on the moon? Before we do, let's think about mining and smelting on Earth. We use huge amounts of water -- huge amounts of power. We consume oxygen and we put out great clouds of gas. But there is no water on the moon, nothing to burn, and no power until we put it there.

Without water the moon hasn't been shaped the way Earth has, with alluvial strata and deposits. Many of its riches are all mixed together in the surface layer of dust. We'll probably begin by surface mining for oxygen to sustain our outposts in space. Metals will be useful byproducts.

Pollution would be a terrible problem if we mined the moon the way we do Earth. The moon's near perfect vacuum is going to be useful in all kinds of processing. If we dumped gases on the moon the way we do on Earth, we'd ruin that perfection.

You see, most gas molecules move more slowly than the lunar escape velocity. Only the fastest ones get away. Now and then, slower ones are sped up as they collide with each other. Then they also can escape. Over the years, the moon loses any gas released on its surface, but not right away. So we have to invent completely closed processes to take the moon's wealth. That way we'll protect one of the moon's greatest resources -- its pure vacuum.

The moon is a rich place, but we must put our minds in a wholly different space to claim its riches. The moon will reclaim our interest as we learn to see more than a slag heap. The moon has held our imagination for millennia, but in a different way each time our knowledge of it has changed. Today, our vision of the moon is on the threshold of changing yet again -- as we learn to look at it with a process engineer's eyes.

I'm John Lienhard, at the University of Houston, where we're interested in the way inventive minds work.

(Theme music)


Burt, D.M., Mining the Moon. American Scientist, November- December 1980, pp. 574-579.
Prof. Donald M. Burt
Geology Department
Arizona State University
Tempe, Arizona 85287-1404
602-965-6180

The Engines of Our Ingenuity is Copyright © 1988-1997 by John H. Lienhard.

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