Alien motives and human assumptions
Earth Is a Gravity Well, Not a Warehouse
Water, metals, carbon, and volatiles are abundant across asteroids, comets, moons, and outer systems — and far cheaper to reach than the bottom of a planetary gravity well.
Established ScienceAnything worth taking from Earth is easier to find somewhere with no atmosphere and no witnesses.
What we actually know
Water ice is common on comets, in the outer solar system, and in permanently shadowed lunar craters. Metals are concentrated and unweathered in asteroids. Reaching any of it requires a fraction of the energy needed to land on Earth and climb back out, and none of it is guarded by a biosphere, a magnetosphere, weather, corrosion, or eight billion inhabitants.
Where the extrapolation begins
If ordinary materials are the goal, Earth is close to the worst source in its own system. The planet is only special for things that are not ordinary: a particular biochemistry, a particular history, or a particular kind of mind. Those are not commodities.
What the novel invents
CROWN's earliest threat assessments assumed extraction. Ninety-three years later the object has extracted nothing, which the assessments have never satisfactorily explained.
Questions to think about
- — Why does the energy cost of a gravity well undercut most invasion premises?
- — What could Earth have that an asteroid belt could not?
- — If they are not here for material, what does that leave?
Where to read next
- — NASA planetary science — asteroid and cometary composition, lunar polar ice
- — Delta-v budgets for solar-system destinations
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