The Extremely Cool Physics of the Moon

Jeff Bezos is desperate to go to the Moon. Elon Musk is heading for Mars. Who’s right? What will realistic engineering look like on the Moon and how will the unfamiliar physics affect life there?

It’s Going To Be A Long Night

The problem is, long nights could make farming and living difficult above ground for most of the surface. That’s one of the reasons the south pole is often proposed as a location for the first human lunar colony: unlike most of the Moon, bits of the poles are in almost constant sunlight.

Did You Hear About the Party on The Moon?

The downside for puny humans of an airless surface is fairly obvious — we have a pesky need to breathe. In that respect, your cracker is right: a party with no atmosphere is unlikely to be a success. I wouldn’t recommend it as your next theme.

For engineering, however, near-vacuum could be useful. There’s no air resistance on the Moon, nothing rusts, and there’s no weather to contend with. Storms are an increasing problem on Earth today and a major issue for the protagonists in my scifi books (which are set 30 years in the future). Fortunately, Moon colonists won’t have to worry about that.

However, there will be meteorite strikes. Any single area on the Moon is likely to be hit once every thousand years. That doesn’t sound much but if the Moon were densely covered with buildings that could be a problem.

Weight Loss Programme

A significant benefit of the Moon’s smaller size is it’s much easier to launch stuff into space from there than from here. If you fire things upwards fast enough, they’ll escape the pull of gravity and make it into space. For any given planet, that minimum firing speed is called the planet’s “escape velocity” and it applies to every projectile, independent of its own mass. The Moon’s escape velocity is 2.38 km/s, which is about twice the speed of a bullet. Our escape velocity is over 11 km/s. It’s much, much harder to fire stuff into orbit from the Earth than the Moon. (Just because I was interested and looked it up, Mars’ escape velocity is ~5km/s).

Another advantage is if you launch something into the “air” on the Moon it will travel a long way before the weak gravity pulls it back down (provided you kept the speed below escape velocity, or it will never hit the ground again). In the 1950’s, the science fiction writer Arthur C Clarke was keen to exploit the zero friction, low gravity conditions on the Moon by using electromagnetic cannons or mass drivers to cheaply and easily move payloads around on the surface and launch them into orbit. He even patented the concept. I’ve used the same idea in my books.


The Future

About the Author

Her new hard science fiction novel came out in December 2019. Denizen 43 (Amazon UK/US) is the third in the Panopticon trilogy.

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Hero image with thanks to NASA.

SciFi author interested in tech, engineering, science, art, SF, economics, psychology, startups. Chaotic evil.