How would you build a spaceship?
I tend to think about many random things, and this happens to be one of them (I think this was precipitated by the Serenity schematic t-shirt), but the mental exercise itself is worth a few minutes. And I might, if I think about it hard enough, have a point to make after that.
What will you use it for? I imagine the initial days of spaceflight would have graduated from being purely exploratory but would still be very utilitarian; think of a base camp established somewhere that would require frequent cargo trips to ferry supplies and building materials. So possibly a tiny pilot cabin, but a huge cargo bay. Straightforward, nothing fancy, maybe some additional supplies depending on how long the run would last. I imagine larger, demilitarized spacecraft could be converted to cargo ships too. Maybe, in times of need, cargo ships would be refitted with weaponry.
As we get better and better at living off Earth, spaceships might be used for bulk human transport and cargo. Perhaps pioneers or colonists; a cliched idea, but one which makes sense if you’re thinking of resettlement or evacuation. In that case, you would need to fit a great deal of people into a small space, as efficiently but as hygienically as possible. I wonder how you’d manage ventilation and air (here’s where a degree in, well, rocket science would come in useful) — possibly recycle the air, or perhaps organize some space for a hydroponics plot to supply a little extra oxygen? (This NASA article, interestingly enough, suggests that the method is already under consideration).
Classic sci-fi space opera is of course incomplete without the occasional intergalactic war, so your average spaceship a few generations into the future of regular spaceflight will probably be equipped with some kind of weaponry system. But I think there’s one basic factor to take into consideration: the forces involved in firing something at someone else. Think about gun recoil: when you fire a gun, the force of the bullet being fired produces an equal but opposite force on the person doing the firing. Messing around aimlessly on the interwebz produced this thread, which led me to the Wikipedia page for railguns, after which my hopes were dampened by this paper. I’d think the problem with recoil would be exacerbated in an almost frictionless environment, but it looks like I can spend the next year or so reading about this online (and absorb a lot of peripheral information about weaponry in general) and still not be done, so that’s a fascinating point that’ll have to be discussed in its own right.
Speaking of energy and forces and such…
What will you power it with?
I somehow doubt green energy (in its present form) offers future spaceships much hope when it comes to powering its engines. There are several things to consider: the efficiency; the cost per unit of use; how to treat the waste, amongst many others. The first two points are probably linked: if your fuel source was incredibly efficient but cost a lot, it might still be a viable option as opposed to something that had 30% efficiency and was readily available. There’s some really interesting information in this website that looks legitimate, but which sounds like a black hole of information gathering. One thing, however, caught my eye: ion propulsion. I’m not sure how I got through these many years without knowing about ion propulsion, but now I’m seriously wondering how well that would work for a spaceship. It wouldn’t look particularly pretty — have you seen those solar panel arrays? — and for larger craft would have to be monstrously big, I’m guessing.
The thing is, sending out small exploratory craft, orbiting satellites or docking stations like the ISS would all require a reasonably constant, predictable energy expenditure. That sort of scenario is much less likely if you’re pioneering out near the Oort cloud or engaging with space pirates. I imagine that more efficient solar panels would be all right to create normal thrust or supply power for simple, everyday activities. But for more energy-intensive endeavors, you might have to go the nuclear route. If I wanted to be nerdily risible, I’d suggest cold fusion reactors. Naturally.
In the meantime we’d have to do with a portable version of fission reactors. Not that that isn’t a cool thought.
What about gravity?
We have a choice with gravity — we can either ignore it, as our current astronauts do, and suffer the eventual consequences of weightlessness, or we can simulate gravity. We could, of course, have advanced enough to actually generate some localized form of gravity, but that implies a mind-boggling level of familiarity with gravity as part of the fundamental (quantum) forces of nature, so I’m going to leave that one out for now.
Simulating gravity isn’t, in principle, difficult. You could generate a centripetal force that generates a normal force towards the center of the ship; that’s a kind of gravitational pull. The centripetal force is proportional to the square of the velocity, as well as to the inverse of the radius. If you want an Earth-like G (approximating 9.81 m/s^2) you’d have to compromise between the speed of the rotation and the radius of the thing that’s doing the rotation.
But you can’t rotate an entire craft all the time, and rotation would surely take up a huge amount of fuel. I’m imagining, therefore, a rotationary chamber that is activated on a regular basis to counteract the effects of weightlessness (which include muscular atrophy). You’d have to have a separate chamber, powered by something short term but reliable (perhaps the solar energy that gets picked up near stars?).
I would think real problems of logistics would occur when you shipped a whole cargo full of people/pioneers into space. Exactly how are you going to take into account all of their masses so as to calculate power and rotational velocity? And where the heck would you put them? That chamber would have to be almost the size of the rest of the rest of the ship.
What will it look like?
Now there’s a thought for a lazy weekend afternoon. I think I’d like my spaceships to be endearingly clunky; none of the Apple Zen for me, thanks. And think about it — you won’t necessarily have to go for a streamlined look if there isn’t any air resistance to slow you down. Maneuverability will, however, be an issue (unless you’re fine with taking five minutes to execute a turnaround. I suppose, in the vastness of space, you can see things coming with enough time to react).
What’s the point of this?
Anyone who thinks it takes an encyclopedic knowledge of formulas to come up with something new in science is…. well, probably highly inaccurate. Discoveries are made by people with imagination, those who combine creativity with fact. And I think that’s the sort of creativity that a question like “How would you build a spaceship?” engenders.
We worked with known facts and what we knew of technology. Then we put them together to imagine possible solutions to the problems of space travel. I think, that if you asked this question to a roomful of children, that you might get them more interested in science than if you simply sat them down with a billion word problems.
Science isn’t cool just because you can use it for everyday things now; science is marvelous because it lets us plan ahead for the next fantastic thing.