Elevators and Loops to Space, Oh My!
I spent some time yesterday playing Cities: Skylines yesterday,1 and something caught my eye. Well, it caught my attention a good bit earlier, but it took me quite a while to meet all the requirements to unlock it in the game.
The space elevator. In-game, it’s mostly supposed to draw tourists,2 which I found to be quite a waste. I mean, my city just spent 1.5 million Local Currency Units building this massive thing, and nobody’s going to use it to start launching cargo to space? That is the entire point of a space elevator, right up until it’s time to start bringing cargo back down.
Later on, I wound up talking to one of my friends about the space elevator, commenting on the design. As far as I can tell, the design they’re using doesn’t feature a tether, or much by way of animation.3 So I assumed that it was some sort of Space Fountain design. What? You haven’t heard of a space fountain? Pshaw, someone hasn’t spent enough time reading about cool space stuff.4
A space fountain is basically a particle accelerator that fires pellets of some kind at super-high speed. Straight up. They’re then5 caught by a station in a geostationary (but technically unstable) orbit. That kinetic energy is used to keep the station in said unstable orbit, and a little bit can be bled off to generate power, if you were too lazy to install enough solar panels. The pellets are then dropped back down, where the accelerator ring catches them. The gravitational energy there, by the way, means that they’re going almost launch speed already, so the whole system is remarkably energy-efficient.
The cool parts about this are twofold: one, it’s way easier to build than a space elevator. You build the launch system, build the station directly on top of it, and then slowly switch it on, finishing the construction of the launch tower6 as the structure gets taller. Two, it’s safer than a space elevator, because if a space elevator breaks, that super-strong cable becomes an ORBITAL DEATH WHIP. Seriously, imagine something strong enough to hold a station in orbit, possibly still attached to said station, falling across half a country with the kinetic energy of a small nuclear strike. That is one expensive pair of shears. On the other hand, a space fountain failing will, at most, obliterate the ground station, and the whole system has enough latency7 that either end would have time to react to a failure, if only to evacuate.
But that isn’t all, because there are some other non-rocket launch systems that’re at least somewhat feasible. I’m not going to talk about orbital rings because that’s not actually something I’d call feasible at the moment, and I don’t know enough about skyhooks to really comment, no matter how cool the name is.
But launch loops? Ooh, let me tell you about launch loops.
A launch loop is, in essence, a fancy maglev system. It’s also 2000 km long and suspended 80 km high, but it’s basically a fancy maglev system.
The idea is that you build a tube 2000 km long, with a loop at either end.8 In the tube you put a thin iron wire. You then use the machinery at the loops to accelerate the iron wire to, what a coincidence, 14 km/s. That rotor as it’s called by the fancy people with degrees in engineering who know more about this than I do, uses that hilarious amount of motion to transfer the weight of the whole structure onto the two loop stations. At which point the rest of the tube (or ‘sheath’ if you want to use Fancy People Words) starts to lift into the air. And then past the air, until it’s just 20 km shy of being in space.
The cool part of this whole thing is that, as of that moment, you’ve got what amounts to a metal loop that can not only pull stuff most of the way up to space already, but also provide them with a swift kick in the rear, providing an almost-stable orbit. Strap on a small engine of some kind, and you can launch a payload of up to 5 metric tons. 80 times an hour. Even if you cheap out on the power plant running the whole thing – say, 1.5 times the Ivanpah Solar Project’s output,9 you can still launch those 5-ton payloads more than 30 times a day.
And that whole system is theoretically possible with modern technology. You don’t need to invent any mass-production method for making elevator strands. You don’t even need a new power plant – the Three Gorges Dam puts out more power than you’d need to run the loop at the aforementioned maximum capacity.
By the estimates of the people smarter than me who came up with this thing, one of these could be built for around $10 billion.
So, if Bill Gates is reading this – look into it, alright? Humanity has all its eggs in one basket, and we really need to work on that.10
- Big surprise. ↩
- Which it hasn’t done very well – my city doesn’t get much tourism in spite of having half the Unique Buildings and, according to the little ‘tweeter’ feed, winning ‘most beautiful city’ for the past twenty years in a row or so. ↩
- It’s got what looks like a rotating radar dish, for some reason, but no actual cars ascending or descending. Oh my god, I’ve just figured it out – the space elevator is a sham, and someone embezzled all the money. ↩
- Don’t get me started on Dyson Spheres. Or… Dyson anythings, actually. Dyson was a mad genius. ↩
- And this is being… actually, not too heavily simplified, now that I think about it. I’m leaving some bits out, but the overall explanation is still fairly accurate. ↩
- And you do need a launch tower, but it’s a fairly simple design, just a tube that maintains a vacuum until the atmosphere gets thin enough that it won’t mess with the pellets. ↩
- The pellets, even though they’re fired at 14 km/s, still take something like 3 hours to get from the base station to the orbital station, and another 3 hours to get back. ↩
- The tube is, of course, doubled, and those loops are, once again, basically particle accelerators, but still. Tube, loops. ↩
- Because you’re an environmentally-friendly little bugger. ↩
- I somehow managed to make it through this entire post without making a single Space Core reference. ↩