What is the one most important thing that makes Earth special for life? You are thinking water, and that’s right…but the funny thing is that Earth has hardly any water at all (by solar system standards).
If the Earth were an apple, you could dip the apple into a bucket of water, pull it out, and the sheen of water on its surface would correctly represent the amount of ocean water on the Earth. It’s hardly anything at all! There are other places in our solar system that have millions of times, even hundreds of millions of times more water than planet Earth. It just happens that the Earth has its very small amount water in liquid form. whereas most other bodies in our solar system have their vast amounts of water completely frozen. It’s that fact that makes Earth so special for life.
This reminds me of the movie Battle: Los Angeles. Trying to explain why the space aliens are fighting to exterminate us, a planetary scientist says that Earth has something the aliens want, something they can’t get anywhere else in our solar system: water in liquid form. Apparently the aliens can build fleets of starships, fly armies through interstellar space, and fight wars of global extermination, but they can’t melt a comet! The truth is, for a technological civilization, Earth is not a good place for resources. For creatures that are technologically ahead of us by just a little bit, the best place would be the asteroid belt! If slightly more advanced aliens ever do invade our solar system and domineer the resources of our asteroid belt, it would possibly doom us to never traveling to another star. We need the asteroid belt. Space resources are critical to our future.
And so this is why we are at such a special time in human history. We are living in the brief moment of time when humans pass from planetary poverty into full ownership of an amazingly rich solar system, moving our civilization to the next higher level. If we act on this moment, then the billion-fold leap in our economic ability will be revolutionary.
A Grossly Incomplete History of Time
Here’s the background story to help us understand our pivotal role. Knowing this, you will begin to see the kind of strategy we need to bring this revolution about. I will leave out many cool details to keep this extremely short.
- The sun began burning and giving off light into the cloud of molecules and dust that surrounded it.
- The sunlight blew the lighter molecules like water far, far away into the darkness.
- Heavier elements like iron and silica remained closer to the sun and clumped into more dust, asteroids, dwarf planets, and planets. These became Mercury, Venus, Earth, the Moon, Mars, Ceres, and all the rest of the asteroids. The bodies closest to the sun (like Earth) were originally bone-dry because the water was all blown away during their formation.
- Far enough away from the sun there is a “Frost Line,” beyond which the lighter elements and molecules like hydrogen and water can clump together to form more planets and Moons. Those became the gas giants Jupiter, Saturn, Uranus, and Neptune, all their icy moons, and the dwarf planets and other icy bodies far beyond Neptune.
- When the rocky bodies (like Earth) accumulated enough material, they got hot and melted. The molten metals then mostly sank to the core of those bodies because molten metal is heavier than the molten rock. The molten rock floated to the top and hardened into a crust. This process is called differentiation. Metals therefore became inaccessible at the surface of planets like Earth because it was all deep down in the core. Bad news for future technological civilizations that will need metals.
- Apparently there were at least two planets (or “proto-planets”) between the distances of Mars and Jupiter that were big enough to undergo differentiation and that later collided, breaking apart into small chunks. These are now some of the asteroids of the main belt. The material from the cores of those two proto-planets are now M-Class asteroids, composed of pure metal. The chunks from the crusts of those proto-planets are a type of S-Class asteroid, composed of stony material. These planetary fragments never re-clumped into a single planet because the gravitational effects of the nearest and biggest planet, Jupiter, kept them stirred up. Thus, the metal of an entire planetary core is still exposed and broken into bite-size chunks in the asteroid belt. Excellent news for a future technological civilization.
Video showing discovery of asteroids from 1980 through 2012, which indicates the quantity of asteroids both in the main belt and near Earth. Some estimates say we have found only 1% of the asteroids, so far.
- Because the asteroid belt is so close to the frost line, the bodies in that region were able to harbor and shelter some of the water from being blown all the way out past the frost line. We now know that many asteroids in the furthest part of the main belt are extremely rich in ice. Ceres, the dwarf planet, is believed to have a million times as much water as Earth. Even more excellent new for technological civilizations, since metals and ices are co-located.
- The icy bodies that formed beyond Neptune (like Pluto) are so far out that they don’t collide very often. Thus Pluto and the three other known dwarf planets in that region, plus the countless other smaller bodies, failed to clump together into a proper planet. (Sorry, Pluto fans.) However, the material did collide often enough to flatten out into a doughnut shape aligned with the plane of the solar system. This doughnut-shaped cloud of icy bodies is the Kuiper Belt.
- Even further out, the material was spread so far apart and so thinly that it collided almost never at all. It did clump into icy bodies, but the swarm of these bodies never flattened into the plane of the solar system. It remains as a spherical cloud of icy bodies surrounding our entire solar system. This is the Oort Cloud.
- All these solar system bodies tug and pull on each other, as do passing stars from beyond the solar system, and these disturbances occasionally send a small fraction of the bodies flying from the main asteroid belt or from the Kuiper Belt or Oort Cloud into the inner solar system. Some are rocky or metallic. Some are icy. The icy bodies from the Kuiper Belt and Oort Cloud are called comets when they fly into the inner solar system.
- These icy bodies, both comets and icy asteroids, brought water back into the bone-dry inner solar system as they crashed onto the planets and Moon that had formed there. This water was now able to persist in liquid form on the Earth and (for a while) Mars, because their gravity and warmth kept the sun from blowing it away again. On Mercury and the Moon the crashing ice formed temporary atmospheres of water vapor that the sun began quickly blowing away again, but a portion of these atmospheres re-froze into the permanently shadowed, cryogenically cold craters near their poles. Mars’ water eventually froze up, too, when its atmosphere became too thin to keep the surface warm. (Venus has too thick an atmosphere and so is too hot for water in any form.) So the Earth has long-term liquid water. Mercury, the Moon and Mars have solid ice: small amounts relative to the outer solar system, but strategically importance because of their locations near Earth.
The M-Class asteroids that crashed onto the planets of the inner solar system deposited some metal back into those crusts. Other metal was brought up by mantle convection from the core and plate tectonics through the crust, for planets like Earth that have those processes. Good news for the beginnings of technological civilization. Enough metal to get us off this rock and out to the asteroid belt.
Zoned for Commercial Use
This history explains the zones of resources we have in the solar system:
- Solar energy is from the center of the solar system.
- Silicate materials are mainly in the rocky planets.
- Metals are mainly in the asteroid belt.
- Hydrogen and Helium are mostly in the gas giant planets.
- Ices are mostly in the outer solar system: moons of gas giants and objects beyond Neptune. This ice includes water, carbon compounds like methane and carbon dioxide, and nitrogen compounds like ammonia.
- Smaller quantities of resources can be found in special reservoirs:
- Ice at the poles of the Moon and Mercury and beneath the surface of Mars.
- Ice and metals in wayward asteroids, and ice in wayward comets. This includes Near Earth Asteroids passing very close to Earth.
- Metals as isolated ore bodies on Earth and probably other rocky planets and moons.
- Liquid water and the organic materials formed by life and accumulated on planet Earth.
Strategy to Grow Human Civilization
Knowing this pattern, we can devise strategies to really make use of our entire solar system and take human civilization to the next higher level. We need to start with the resources that are easiest to reach, first. We started on the Earth, and our civilization grew so large that it is starting to feel the squeeze of this planet’s limitations. Other life on this Earth still needs these resources, so let’s not be greedy for just this one planet. The next most accessible resources beyond the Earth include those of the Moon and the Near Earth Asteroids (NEAs). Those resources are limited reservoirs, too, being in the dry inner solar system, but fortunately they are large enough to get a healthy, robotic space industry started. Then the industry can set up a transportation network to begin utilizing the asteroid belt, and eventually the outer solar system so that we can access the billion-fold greater resources of of this, our amazingly wealthy home.
So here is a simple, top-level strategy:
- Develop our capabilities using the resources of Earth (Kardashev Type 1 civilization)
- Use the resources of the Moon and NEAs to establish industry in space in a convenient, nearby location while it still relies on some parts and materials transported from Earth
- After achieving full self-sufficiency in space, leave the very limited resources of the innermost solar system and move industry to the Asteroid Belt so it can vastly increase in scale (moving toward Kardashev Type 2 civilization)
- When able, expand the transportation network to include the outer solar system and thus vastly increase the scale of industry again.
- Colonizing the Milky Way will now be easy. (Begin moving toward Kardashev Type 3 civilization.)
This is heady stuff, so I am anxious to return to the original topic: how we can all personally, individually take part in the exploration and colonization of space! But there is one more topic I need to discuss first. How realistic is it for us to access the wealth of solar system resources within this generation? That’s what really motivates me to help everybody get involved, and that’s the topic for the next post.
Please let me know your thoughts about this! There is a lot of room for disagreement, and I would love to hear other views.