by Fraser Cain

By popular request, Isaac Arthur and I have teamed up again to bring you a vision of the future of human space exploration. This time, we bring you practical construction tips from a pair of Type 2 Civilization engineers.
To make this collaboration even better, we’ve teamed up with two artists, Kevin Gill and Sergio Botero. They’re going to help create some special art, just for this episode, to help show what some of these megaprojects might look like.

I’d also like to congratulate Gannon Huiting for suggesting the topic for this collaboration. We both asked our Patreon communities to brainstorm ideas, and his core idea sparked the idea for the episode. You get one of my precious metal meteorites, which I guarantee will give you a mostly worthless superpower.
We’ll tell you the story of what it took to go from our first tentative steps into space to the vast Solar System spanning civilization we have today. How did we extract energy and resources from the Moon, planets and even gas giants of the Solar System? How did we shift around and dismantle the worlds to provide the raw resources of our civilization?
Lunar Rover Concept. Credit: Sergio Botero
Humanity’s ability to colonize the Solar System was unleashed when we harvested deposits of helium 3 from the Moon. This isotope of helium is rare on Earth, but the constant solar wind from the Sun has deposited a layer across the Moon, though its regolith.
Helium 3 was the best, first energy source we got our hands on, and it changed everything. Although other kinds of fusion reactors can produce more energy with more efficiency, the advantage of helium 3 is that the fusion reaction releases no neutrons. This means you can have a fusion reactor on your starship or on your base with much less shielding.
Multi-dome base being constructed. Credit: ESA/Foster + Partners
We still use helium-3 reactors when living creatures need to be close the reactor, or the ship can’t afford to carry around heavy shielding.
The Helium 3 is found within the first 100 cm of the lunar regolith. Harvesting it started slowly, but in time, our mining machines grew larger, and we stripped this layer completely off the Moon. There are other repositories across the Solar System, in the regolith of Mercury, other moons and asteroids across the Solar System, and in the atmospheres of the giant planets. We later switched to getting our Helium 3 from Uranus and Neptune, but the Moon got everything started.
A huge lunar miner, with astronaut for scale. Credit: Sergio Botero
One of our big problems with building in space was getting raw materials. Just about every place that has the supplies we needed was at the bottom very deep gravity wells which made accessing those materials a lot harder. Asteroid and moons offered us a large supply of material that was not locked inside such deep gravity wells.
These asteroids also gave us a big initial head start on developing space-based infrastructure as they contained a great deal of precious metals that we could bring home to help fund our endeavors.
For all that, the entire Asteroid Belt contains much less material than Earth’s own Moon. The ease of mining and transport on these bodies made them a critical source of raw materials for building up the early Solar Infrastructure and many of them became homes to rotating habitats buried deep inside the asteroid, where millions of people live comfortably shielded from the hazards of space and support themselves mining the asteroid around them.
Artist’s impression of the asteroid belt. Image credit: NASA/JPL-Caltech
These asteroids and moons often contained water in the form of ice, which is vital to creating life-bearing habitats in space, as well as fuel and propellant for many early-era spaceships.
However, even if the entire Asteroid Belt was ice, instead of it being a fairly smaller percent of the mass, that would still only be the approximate mass of Earth’s Oceans. There was a plentiful supply for early efforts but not enough for major terraforming efforts on places like Mars or creating many artificial habitats.
Water is incredibly scarce in the inner Solar System, but becomes more plentiful as we make our way further out, past the Solar System’s Frost Line. Deeper out past the planets we find enough water to make whole planets out of, as hydrogen and oxygen are the first and third most abundant elements in the Universe. Also, for the most part these come in convenient iceberg-sized packages, low enough in mass to have a small gravity well and to be movable.
Mastering the Solar System required moving very large objects in space. For the less massive objects, we could put a big thruster on it, but for the largest projects, such as moving planets with atmospheres (which we’ll get to later in this article), another technique was required.
Concept for a possible gravity tractor. Credit: JPL
To move large objects around, without touching them, you need a Gravity Tractor.
Want to move an asteroid? Use the gravity of a less massive object, like a spaceship. Hold the spaceship close to the asteroid, and their gravity will put them together. Fire your rocket’s thrusters to keep the distance, and you slowly pull the asteroid in any direction you like. It takes a long time, and does require fuel, but you can use this technique to move anything anywhere in the Solar System.
Put a massive satellite into orbit around an asteroid. When the satellite is on one side of the asteroid it fires its thrusters towards the satellite. And then on the other side of its orbit, it fires its thrusters away from the satellite. The satellite will have been pushed twice in the same direction. To an outside observer that satellite has moved, though on the asteroid it will seem to have been nudged closer than put back.
Don’t forget that the satellite pulls on the asteroid with just as much force as the asteroid exerts on the satellite. Earth pulls on the Sun just as hard as it pulls on us, but it’s more massive so it doesn’t move as much. But it does move, and so by pushing on the satellite towards the primary then pushing away on the opposite side, we move the primary body.
We can also take advantage of momentum transfers from gravity to alter the course of an object by making a close flyby. You can use this gravitational slingshot to use the gravity of a planet to change the move large objects into a new trajectory.
Over time, we put gravitational tugs into orbit around every chunk of rock and ice that we wanted to move, shifting their locations to the best places in the Solar System.
Artist view of an asteroid passing Earth. Credit: ESA/P.Carril
Some places gave us raw materials. Other places would serve as our homes.
Earth is the third closest planet to the Sun and it will always be the environment we’re trying to replicate. Earth is, well, it was… home.
For all the millions of other worlds across the Solar System, we made them capable of hosting life  with a little work. Often we could make them habitable just by increasing the amount of energy they received from the Sun.
Creating artificial gravity by spinning a habitat or breathable air by doming it over did us no good if there wasn’t enough light to melt ice into water or let plants grow.
The farther you get from the Sun, the less light you get, but we bounce light that would have been lost, concentrating it to let life flourish. The Sun gives off over a billion times the light that actually reaches Earth, so there’s no shortage in quantity, just concentration.

Read more on Universe Today.