Yesterday, I said that today we would look at some of the specialized facilities needed for orbital operations. Well, I was wrong. Before we get into that, I think we need to do a bit more background for the thought experiment.
Right now, pretty much everything we put up is cylindrical, for aerodynamic reasons. While aerodynamics don’t matter in orbit, they do on the way up because all the different stations have had to have their components made on Earth and carried up on rockets. Hence, cylindrical shapes. Even non-cylindrical items have to be carried up in cylindrical containers.
Now, in orbit, particularly the lower orbits, you do get drag. It’s why the ISS has a power module to raise it back up to altitude every so often. It’s why things dropped in orbit, be it a camera (butterfingers!) or something else, do eventually de-orbit and (hopefully) burn up on the way down. Problem is, the smaller/lighter the object, the longer it stays in orbit. Once you get up to GEO, that ceases to be a major issue, which is why all the big plans for space stations/colonies have focused on being built there.
Let’s revisit that debris for a moment. In the original post that sparked this thought experiment, I mentioned that someone could make a fortune devising a way to collect that stuff. It’s not just that a good bit of it could be recycled in orbit for other projects, it’s because it is a menace to ongoing low-Earth operations. That chip of paint is moving at a speed where it will do a fairly good imitation of a bullet if it hits something. That bolt floating around? It could do some serious damage to anything it hits. Many of the micropunctures experience by ISS and other structures don’t come from meteorites but from other space debris.
Keep that in mind because until someone does get the financial incentive to clean things up, the problem of debris is only going to grow. Especially if the Russians keep testing anti-satellite systems by taking out dead satellites in low-Earth orbit. That’s another reason the ISS has a power module: sometimes you need to change orbit to avoid that debris so the crew is not having to make emergency repairs. Or worse.
There have been a number of suggestions over the years to protect orbital facilities, from electrostatic means to actually building modules like submarines with inner and outer hulls. One of the more, er, interesting proposals was to put a big slab of something out a distance from a module/structure in the most likely direction for debris. The problem with that concept were/are: the cost to launch the big slab of something; and, it can only protect in one direction and you have debris coming front, rear, side, top, etc. There are some other minor issues of orbital mechanics and such, but those can wait.
So, let’s start making this a real thought experiment by considering the following information.
Initially, what gets built will have to come up from Earth. However, we are not necessarily constrained to cylindrical. What goes up will have to go up in a cylindrical container, but we could send up carbon-fiber or other advanced material trusses, frameworks, etc. that can take on pretty much any shape. Cubical, open framework, or even say a frisbee-like shape that could have significant safety advantages for in-plane orbital debris strikes. The only limits are our imagination and the constraints imposed by the height of orbit. Once you are at GEO, there’s pretty much no limit.
Now, add in two other factors. One, if one of the first things up is some sort of foundry operation, you can collect some of the larger chunks of debris and melt them down, reform, and start building. Admittedly, there are some legal challenges as various countries and others still claim ownership of dead satellites, major chunks of debris, etc. Though I will not that even though they don’t want anyone else touching their stuff, they also don’t claim liability for any damage caused in orbit or via re-entry by their stuff. For our purpose, let’s just treat it as a law-of-the-sea issue and plan on using/reusing the materials.
Second thing to consider is that lunar soil/dust is reported to make excellent concrete. If it is reductive concrete (or can be made so cheap and easy) all the better. Great for building a lunar base, and if someone developed a robotic system to grab such, get it to orbit, and send it to the appropriate orbit, who says your structures have to be metal? Add in spin-casting and you’ve opened up a new range of possibilities.
And, I’m going to throw in a third thought for the day. There are other resources available in/near Earth orbit. Start with meteorites and asteroids for metal, but keep in mind that depending on composition even non-metallic asteroids could potentially provide other advanced materials as well as base components.
Rant/ The STS/Shuttle system made use of an external tank that contained tons of oxygen and hydrogen, even after hitting orbit. There were several proposals made to use those tanks as the basis of a space station. NASA said it wasn’t possible, they weren’t interested, and they very much didn’t want anyone else (particularly a commercial operation!! Commercial was and is in many quarters a nasty word to NASA) to do anything with them so they actually expended energy to de-orbit the tanks during the launch process. Yes, the Shuttle actually went down, released the tanks, and then climbed back up to a higher orbit. Which is sad as there were proposals to instead raft the tanks together, inter-connect them, attach thrusters to keep them in a good stable orbit, and have those tons of oxygen and hydrogen available for future use. For now, we are going to need such until orbital and extra-orbital operations can secure those resources via other means. /Rant
So, we have options in regards materials, shapes, and more. We are not limited to low-Earth operations in anything except the short-term. So, are there any other pre-conceived notions we can and should stand on their head before we get started? Who knows, find out tomorrow on the next episode of “As The Satellite Tumbles”
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