To Crush the Moon

Planetary Descriptions

For the curious, the Lalandean world of Gammon and the Wolf 359 world of Pup, which are mentioned briefly in Chapter 10 and form the twin seats of the Biarchy government in Chapter 25, are described in more detail by this series’ previous volume, Lost in Transmission.

Saturn’s A, B, and C rings—by far the most visible at a distance—are 15,000, 25,800, and 17,400 kilometers wide, respectively, as measured from the inner to the outer edge. Their outer diameters are obviously much larger: 274,000, 235,400, and 183,500 kilometers, versus 120,700 km for the planet itself. By comparison, the Earth’s diameter is only 12,750 km. The observation platform described in Chapter 8 is just inside the orbit of Mimas, the innermost of Saturn’s large, spherical moons. Notably, it’s also inside the sparse E ring, which is thought to extend to a distance of eight planetary radii and to include a number of the inner moons. Please note that this book relies on pre-Cassini data. I had a hand in the launching of that spacecraft and will be following it with great interest, but as of this writing it has not yet reached the planet.

As described, the planet Mulciber in the Epsilon Eridani system is possible only if it’s close enough to its parent star that the ambient heat will melt tin and drive off light gases such as oxygen and nitrogen. Also, for heavy metals to occur in such abundance at the planet’s surface, Mulciber must have been shattered by a collision of some sort, in such a way that its light, rocky crust has coalesced into a separate moon—Aetna—while its exposed iron core re-formed into the planet Conrad describes.

Stephen L. Gillett (while not mentioning a world as strange as Mulciber) outlines some of the details of this process in his excellent reference World-Building (Writer’s Digest Books, 1996), but it’s worth mentioning that something very similar appears to have happened to Earth. If the mass of our moon were distributed on top of the existing Earth, as it seems to have been in the early stages of the solar system’s formation, we’d have a much thicker crust with much lower metal content near the surface. If the Mars-sized body which struck Earth had done so less glancingly, our planet might well have become an iron cannonball with a much larger moon. A straight-on hit could even have pulverized the Earth, forming a second asteroid belt, although it’s likely that a planet of some sort would have re-formed from the shards eventually.

The Squozen Noon

The atmospheres of planettes like Maplesphere and Ash are not stable over geologic time, or even the span of a few years, without a replenishment mechanism and/or a mechanism for keeping the upper atmosphere very cold. Make no mistake: these are technological artifacts, like buildings, and will not persist forever without stewardship.

Lune, the Goliath of planettes, does not have this problem, and will keep its atmosphere indefinitely. With a radius of 707 km (reduced from the original 1738 km), a surface gravity of 1.0 gee, and an unaltered mass of 7.3¥10²² kg, Lune’s escape velocity is 3.72 kilometers per second (vs. 11.9 km/s for Earth). This is more than enough to retain oxygen and nitrogen, but also small enough to make access to space a lot easier than it is from Earth.

The delta velocity necessary to reach Varna—in an orbit 50,000 km high—from Lune’s surface is very close to the escape velocity:

Fortunately, this is achievable through low-tech means, as we see in Chapter 19.

Note that Lune’s sphere of influence—the maximum radius of a stable circular orbit—is just over 65,000 km. Past this point, the gravity of Earth (even Murdered Earth) will perturb the orbit over time, until the orbiting object either crashes, is ejected from the Earth-moon system, or becomes a stable satellite of Earth.

The dimensions of Lune give it a surface area of 6.28 million square kilometers—about 17% of its original area, or 1.7% of Earth. This is slightly smaller than the continent of Australia, and while it includes ocean as well as land surfaces, it does create a plausible home for hundreds of millions of human beings even at sub-Queendom technology levels.

Because angular momentum is always conserved, reducing the diameter of Luna from 3476 to 1414 km (almost exactly a 60% reduction) will increase its rotation rate. For a sphere with a mass M, rotation period P, and radius r, the angular momentum is (2⁄5) (Mr²) (2p/P). Thus, r²/P is a constant, and reducing the radius by 60% decreases the rotation period by a factor of 6. As a result, the moon’s current solar day of 29.53 Earth days (708.72 hours) is shortened to 4.92 Earth days (118.12 hours). By crushing to slightly less than 60%, the day can be adjusted to exactly 5 earth days, or 120 hours.

The original soil composition of Luna is compared with the Earth’s crust in the table below:

So, from a terraformer’s perspective Luna is not a bad piece of real estate once the gravity problem is solved. The only real problems are a lack of carbon and hydrogen in the Lunar soil, and an overabundance of toxic nickel. The figures on nitrogen are misleading, since Earth’s atmosphere contains a huge reservoir of this element, whereas Luna has no such resource. A dense nitrogen atmosphere is certainly necessary to support Earthly life, so one would need to be imported.

Wellstone

I’ve written a great deal about this subject elsewhere, and will not repeat it all here. For now, I’ll just say that although it sounds far out—and I’ve pushed the limits of credulity pretty hard here—this is a mostly real technology which is currently under development. Readers interested in learning more are encouraged to check out my nonfiction book on the subject, Hacking Matter (Basic Books, April 2003), or the web site www.programmablematter.net.

Positronium

The “positronium” material mentioned in Chapter 11 is a real substance, consisting of a semistable “atom” with an electron and positron (or antielectron) orbiting their mutual center of attraction. The positronium atom has no nucleus, but it does have a definite size, and in fact the Air Force Research Laboratory has investigated quantum dots (and by extension, wellstonelike quantum-dot solids) as a means for storing this explosive in microgram quantities. According to Gerald Smith of Positronics Research in Los Alamos, New Mexico, when the electron and positron are collided together by shock or high temperatures, each microgram of positronium releases the energy equivalent of 40 kilograms of TNT. Thus, the potential for positronium-in-wellstone as a fuel or a munition is considerable. A BB-sized pellet of the stuff could easily sink a battleship, or propel a Volkswagen to the moon.

Blindsight

Again, a real thing, although the dolcet berry is not. Interested readers should check out V. S. Ramachandran’s fascinating Phantoms in the Brain (Perennial, 1999).