Perihelion Science Fiction

Sam Bellotto Jr.
Editor

Eric M. Jones
Associate Editor


Fiction

A Breath of Aphrodite
by Rebecca Birch

An Undiplomatic Incident
by Paul R. Hardy

Deus Ex Parasitus
by Josh Pearce

Dust to Dust
by Richard Wren

Space Horses
by Diane Ryan

Mercy Park
by Patrick Wiley

Patient, Creature
by Andrew Muff

Planiform
by Timothy J. Gawne

Shorter Stories

Turn Off, Tune Out and Reboot
by J.R. Hampton

Sky Widows
by Matthew F. Amati

Crottled Greeps
by John Teehan

Articles

This is the Way the World Ends
by Carol Kean

A Reason for Returning to the Moon
by Eric M. Jones


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Editorial

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A Reason for Returning to the Moon

By Eric M. Jones

YEARS AGO I CAME ACROSS an odd but charming autobiography titled “Dr. Panto Fogo,” which translates to “Dr. Pants on Fire.” In it, Philip K. Saunders describes a land rush where all the miners were lined up hoping to claim parcels of alluvial diamond-rich hinterland in South Africa. The starting gun fired and everyone rushed off except one guy named Duncan, who ventured off at a right angle to drive a claim stake in the only available parcel to possess any water at all. He got rich, trading water for diamonds, finally selling the claim to a syndicate. Years later Saunders witnessed the very same guy in another land rush—copper this time—who staked a claim on the only available deposit of limestone, necessary to make the concrete for the massive mining infrastructures that were sure to be built, when everyone else was out searching for copper.

So what is valuable often depends on where it is found.

Let’s face it, there are almost no good reasons for returning to the Moon. Twelve U.S. astronauts visited there and a number of countries have landed robotic RC vehicles on it. This is almost ancient history now—memories of that Golden Time in space exploration—the Space Race. But the Moon is an incredibly harsh mistress covered by blasted rock with edges much sharper than razor blades. The material is incredibly abrasive to equipment and spacesuits. (Remarkably similar to slag from steel mills). Nothing much was found there, except rocks of various kinds. Rocks and rocks and more rocks.

I have written before that if one understands how far away the Moon is (much, much, farther than you imagine ... 30 Earth diameters), and what it costs to get there, (“billions and billions”) and what you find when you get there, any reason for going there ... simply disappears.

But I want to be fair: a lunar-farside observatory might be useful, because the interference from Earth would be minimized. A supplies-to-Mars railgun launching facility might someday be useful. A high-security prison seems to be farfetched, but I know a couple guys who should be in it. Vacationing on the Moon seems less appealing than vacationing in low Earth orbit ... or at any Club Med.

But recently there has been a discovery that makes going back to the Moon sensible: the Moon has water on it. A lot of water. Estimates vary but it could be as much as six trillion liters. Or for those not familiar with the metric system, 2.4 million Olympic-size swimming pools full of water.

Now, water is useful in many ways. It can be electrolytically decomposed into hydrogen and oxygen. It can be used for human consumption and used to grow crops. Life itself almost certainly depends upon water.

But surely one can lift water from the Earth’s surface more cheaply than one can mine it on the Moon, unless of course, one needs a lot of it, a whole lot of it. Heavy-lift rockets have launched a record 77,100 kgs into Low-Earth orbit in one launch (1/32 Olympic-sized swimming pool). But putting this much water into space is impractical. Mining it on the Moon turns out to be more cost effective.

What could one do with this water? For one: clean up all the Earth’s orbit of space junk!

For a long time I have envisioned a program where satellites could use sublimated water vapor to gently emit thin fogs to deorbit space junk. This is still possible but expensive in the long run with Earth-furnished water. Then I began to see that returning to the Moon might have some useful purpose after all!

If water from the Lunar poles could be collected it would not be hard to move substantial quantities of it to the L1 Lagrange point between the Earth and the Moon. This is an unstable Lagrange point but only a very little energy is required to remain in this position. In fact, very little energy is required to orbit something around the Earth and Moon from L1. (By the way ... the “geosynchronous orbital position” around the Moon is the Earth, but not vice-versa, as the Moon has one face locked to the Earth. The Moon is in a “supersynchronous orbit” of Earth, orbiting slower than the Earth’s 24-hour rotational period.)

So the plan would be to build a station and accumulate vast quantities of water in the L1 position. On the Moon, ice would be mined, melted into water and filtered. Large quantities would be boosted into orbit by railgun accelerators from the Moon to the L1 position. In fact, it could be stored as water or ice in Mylar tanks.

To understand how this works it is necessary to describe what happens to water and ice in a vacuum. We are surrounded by water vapor. Both ice and water are familiar. When ice is in a vacuum and above 150K, it turns to vapor without going through a water phase at all. This is called “sublimation.” The familiar carbon dioxide “dry ice” behaves this way. Liquid CO2 at normal pressures and temperatures simply does not exist.

But things are not simple. Remarkably, the mechanism of making liquid water turn to vapor in a vacuum has not been well studied. Any fine spray of water in a vacuum will either turn to ice crystals or vapor depending on temperature, time, initial conditions, and ambient solar flux. Thus, whether this is done in sunlight or shadow also matters. Even if the water vapor turns to ice again, the ice will sublimate eventually.

So the ship in orbit around the Moon and Earth would be designed to launch quantities of water which almost instantly turn into vapor but would still be in free fall towards the Earth. The thought that this bombardment would be drifting downward like fog is an error. It could be propelled at high speeds and accelerated by the pull of gravity.

This vapor bombardment would cut across the orbit of all the space junk. It would be carefully aimed to miss the satellites, space stations, and everything that has a legitimate reason for being there. Old satellites in parking orbits above the geosynchronous orbit (the Clarke Orbit), could also be deorbited, but there are better ways of doing that. This proposal is for space debris too small to be handled manually.

Space junk would collide with the vapor and slow down. It would soon be removed from orbit.

Every small particle and other debris would run into the vapor column and experience a momentary down-force and a sudden deceleration as it encounters the vapor. This fog is carried ballistically down into the Earth’s upper atmosphere, where it would be seen as slightly odd-looking, but harmless ice clouds.

Cleaning the orbits of debris might be like trying to sweep a busy highway while the traffic is traveling full speed. But it is only a problem of orbital calculation to avoid the important stuff while sweeping in-between it. The stream of water vapor would be interrupted to allow transit of satellites. This is somewhat likeeric article playing an advanced game of Frogger. But of course the computer is playing against the orbiting junk.

[Left, robotic sprayship blasting vapor toward Earth, clearing the orbital lanes of space junk.]

Now, there are associated problems that need to be solved. The water ejected from our craft could start out as water vapor, but having it fall as water vapor to where the work is to be done takes some planning. Perhaps the “shots” need to be taken only on the Earth’s daylight side. A vacuum chamber that could be used to test this idea is easy and cheap to build; it would be small diameter and tall ... and cold.

Much can be learned from the study and exploration of comets and their tails, which are thought to be separate water vapor and dust tails. The water vapor tails ionize in the sunlight and, of course, are pushed by the solar winds. (It is commonly believed that comets are well understood, but comets contain many puzzles yet to be solved.)

***

Now lest you think that space scientists and engineers would think this proposal preposterous, there are actually plans to mine the Trojan asteroids, and deorbit the big bulky retired communication (and other) satellites from geocentric parking orbits. And, in fact, harvest the existing satellite graveyard for parts.

The Swiss, people always happy with order and neatness, plan CleanSpace One, to launch in 2018 to identify and retrieve low-Earth-orbit (LEO) satellites.

There is even a plan to remove the entire Van Allen Belt.

The US satellite, Explorer 1, in 1958, discovered the Van Allen Belts. There are two of them. The inner belt stretches from 650 to 9,700 kilometers above Earth’s surface and the outer belt stretches from 13,500 to 58,000 kilometers above Earth’s surface.

For reasons that were long a mystery, a slot of empty space separates the belts. Why there is a region between the belts with no electrons? Probes have shown that the inner edge of the outer belt cannot be penetrated by electrons, due to the Earth’s magnetic field. The Van Allen Belts represent a hazard to using the space they occupy, and manned craft transiting them, but are they really worth removing? An Washington-based aerospace company called Tethers Unlimited Bothell thinks so and has a plan to remove them.

But they will return because the Sun fills them up. Besides, they apparently serve a purpose in preventing the same radionuclides that fill them from hitting the Earth. So this might never happen.

***

The idea that all of these far-reaching plans could never be achieved is falling aside. The major spacefaring nations have bigger and more reliable launch vehicles, more elaborate plans, better technologies, and the future looks bright.

Have no illusions: this program will take years and push millions of tons of water through the orbital paths of space junk. But it will be relatively cheap, and it should work well in terms of the physics. Most of it can be remote controlled—no crew need be in the orbiting ship. Most of the human crew, if any, would be at the mining operation.

Scientists are developing two separate missions to assess lunar resources. These projects—Lunar Flashlight and the Resource Prospector Mission—are targeted to blast off perhaps in 2017 and 2018, respectively.

“If you’re going to have humans on the moon and you need water for drinking, breathing, rocket fuel, anything you want, it’s much, much cheaper to live off the land than it is to bring everything with you,” says Lunar Flashlight principal scientist Barbara Cohen, of NASA’s Marshall Space Flight Center.

It’s therefore important to “understand the inventory of volatiles across the whole moon and their purity, and their accessibility in particular,” Cohen adds.

Lunar Flashlight is working toward launch date in December 2017, when it would blast off on the first test flight of NASA’s Space Launch System megarocket, along with several other payloads. Space mining advocates envision lunar extraction of minerals and ice as near-term objectives. the end

Eric M. Jones is the Associate Editor and co-founder of “Perihelion.” He is a design engineer, consultant, entrepreneur, and pilot, working in the experimental aircraft community, NASA, space transportation companies, and the ISS.

 

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