Editor's Desk

By Michael Hughes

Let's go moon tanning


It's such a cool sounding word. According to the Online Etymology Dictionary, it combines the Greek words "rhegos," meaning rug or blanket, and "lithos," meaning stone. It refers to the loose rock, soil and dust covering the surface of rocky planets like Earth and Mars, along with other extraterrestrial bodies like asteroids and the moon.

In grainy Apollo space mission videos, you can see landing craft disturbing regolith dust as they descend onto the moon. Astronauts kicked up the dust when they walked, hopped and occasionally fell down on the lunar surface.

Regolith also is the key to humanity's drive to become an interplanetary species, according to Behrokh Khoshnevis, who wrote this month's cover story. Starting on Page 28, "Ask for the Moon" details research by the University of Southern California IE professor and his team to build extraterrestrial bases via 3-D printing and robotic technologies.

It costs a pretty penny to carry payloads to other spots in the solar system – Khoshnevis says $100,000 can put 1 kilogram in orbit around the moon – so space travelers should think twice about putting in the outdoor hot tub for working on their moon tan.

But Khoshnevis' Contour Crafting, Selective Inhibition Sintering and other advancements have built models from various concretes made with simulated regolith – both the Martian and lunar kind. After all, Europeans didn't ship in Old World trees to build their settlements in the Americas.

The technical challenges remain vast. Moon-based structures must handle extreme temperature ranges and bombardment by space debris. Outside of Earth's atmosphere, most building activities will require work in a near or total vacuum. And without lubricating water, molten concrete could clog extruding nozzles.

But these challenges are surmountable. What's more, Khoshnevis believes 3-D printing could revolutionize construction on the third rock from our sun. Think of housing built in disaster areas in one day vs. the current building time of several months.

So take a look at the story and let us know your thoughts. Perhaps this generation or the next will summer on the moon instead of in the Mediterranean.

Michael Hughes is managing editor of IIE. Reach him at mhughes@iienet.org or (770) 349-1110.