As you can guess from the image, I have a bias towards certain methods of starship construction. Mostly because at this point in time, we lack the ability to push sizeable objects into space from Earth, but also because I like to imagine big.
Star Trek is, once again, one of the most memorable shows that springs to mind when discussing space travel related possibilities. If I try to imagine a relatable show which features in-space dry docks (or whatever the space dock equivalent should be called), then images of the various Enterprise ships is what springs to mind. However, right now, things are a bit difficult if we intend to work on that level.
Truth be told, everything is a bit difficult right now, but actually manufacturing thousands of tonnes worth of machinery in orbit is a definite no-go. Mining an asteroid, on the other hand, is merely vexing.
See, if you’re going to build a spaceship, you need three major things:
- structural integrity
- protection from the elements
- reaction mass
And again, if we’re going to build smaller, zippy ships to help us get around, then construction on Earth is where we start, but as soon as possible after that point, once we progress to permanent structures for habitation, we need to be building in space, and the one thing that space has in abundance (other than a big fat wad of nothing, radiation, vacuum and death) is rocks. They’re big, plentiful, useful, and full of stuff like hydrogen, carbon, oxygen, iron, zinc and a bunch of other really important chemicals (not to mention radioactives for fuel). This makes them ripe for the picking, they just have to be parked in the right place.
The interesting thing is that asteroid mining serves many ideals at the same time: it’s a way to get purer elements than from normal Terran sources, it’s essentially non-polluting (as there’s no ecosystem in space to worry about) and it also has the byproduct of accidentally producing a massive, space-worthy, protected structure which is pretty much perfect for extended habitation in space, not to mention the fact that any halfway decent mining operation is not going to need refuels from Earth for either air, water, food or reaction mass once the whole shebang is up and running.
By the way, reaction mass, if you’re not familiar with the word, is a fancy name for “stuff we can throw out the back of [a rocket] to make it go faster in the other direction”. And hollowing out a big rock in space produces a lot of “stuff we want to throw away” which can be coincidentally used to help put the rock where it needs to be rather than were it currently is, which probably isn’t in a nice, stable orbit or at some Lagrange point – and best of all we can do it remotely if we’re clever enough. The only downside of asteroid herding is that it’s often very, very slow…
So, how do we actually mine an asteroid? Well, the short version is “pretty much the same way we do on Earth” – this means that we need to ship up into LEO and then blast off to the right place some very specialized machines, high enough up in the chain of production that we can use them to produce the stuff that we need to produce the stuff that we need to produce the stuff that we need to… you get the picture. We need machines that make machines, that make machines, and so on.
That, and a large quantity of explosives – seriously, the easiest way to produce a liveable area inside an asteroid (and it is inside we want, where we are protected from the vacuum of space and the harsh radiation), is to drill a deep hole, stuff down some materiel that goes boom and then let it pulverize a cavern at the bottom, then scoop out the remains, purify it, and use it to produce the air, water and soil that is needed, and filter out the metals and other interesting stuff for trade with our home planet.
Of course, having a large floating rock in Earth orbit has its downsides, namely that it’s yet another object that needs to be avoided by all the communications satellites and other tech we have up there, but if we’re in orbit, then once we’ve finished refining the product, if we’re not producing something delicate which needs special treatment, then we can more or less drop it and let gravity do the rest. It’s an almost free delivery system. The difficulty is in the initial setup, not least because the bootstrapping requires a lot of support, and any expedition to an asteroid will last years before the rock is in a trajectory we can be happy with, and the going is going to be awfully tough for a long time, and very, very dangerous. The payoff, though, is incredible – an asteroid is worth trillions of dollars in raw materials alone.
If an asteroid is large enough, however, not only can we live on the hollowed out insides safe from harm, but we can rotate it along an axis and produce the closest thing to gravity there is for essentially free, using just centrifugal force. This will let humans live and work in an almost natural environment, where we can have lakes and even small seas, walk about normally and not worry about bone degradation or our things floating away and clogging up the airvents.
And then, of course, once we have a large enough, self-contained microcosm world, it’s ripe for use as a generation ship…
This isn’t a new idea – one of the very first star trek episodes was “for the world is hollow and I have touched the sky”, about a lost generation ship inside an asteroid. It’s been a staple of science fiction for a long time, but the interesting thing is that it’s not only possible, but it’s becoming practical, and some very influential people are getting interested in the idea.