In case anyone doesn't remember, or if you're just now joining this comic, that creepy looking fanged robot lurking in the ventilation shaft is same zombie bot that first appeared eleven pages back, on page 156. It hitched a ride on the freighter stowed away in a cargo container, and now it's carrying out its mission. What is that mission? We don't know yet, but since it's taking instructions from the apocalyptic villainess Osprey, it's safe to guess it's up to no good. And from the looks of the pointy arsenal it's packing, it's also safe to say that part of that plan will involve doing unpleasant things to any inconvenient humans who get in the way. Bad news for our freighter crew.
As you've surely noticed, the crew habitats on the freighter (it's named the Diablo, in case you were curious) are not a spinning torus like you see in a lot of sci fi. Instead, they're just simple crew capsules at the end of tethers. Why'd I go this route instead of the usual spinning space wheel?…
When it comes to artificial gravity in sci fi, most of us immediately picture something like the rotating spaceship in Interstellar or Discovery One from 2001: A Space Odyssey. But you don't need to build a big honkin' wheel in order to have artificial gravity. And it would have to be big, by the way. According to SpinCalc, in order to get Earth gravity without a noticeable Coriolis Effect, the radius of your Giant Space Wheel would need to be at least 223 meters (that's 733 feet, almost two and a half football fields, which means five football fields all the way across). That's a whole lotta spaceship!
Unless you actually have need for that much living area, there is no reason to build your spaceship like a giant wheel. For something like a space station, that makes more sense, but for a spacecraft, you want to have as little extra mass as you can get away with. So that's why I went with the tether design. It's lighter and simpler, and it works just as well. (assuming you can build tethers that strong)
How do they go back and forth between the habs and the main section of the ship?
They use hab transit modules, which are basically little elevators that ferry you from the habs to the rest of the ship. Sergei and Ula were making out inside of a transit module on page 157.
Isn't that insanely unsafe? Like, what if a space rock comes by and severs your tether? Wouldn't you go flying off into the void?
Yes and no. It is unsafe, but then all space travel is unsafe. Hitting a space rock is bad news no matter where you are. If something did sever the tethers, you definitely would get slung off into space like a slingshot, but remember, you'd still be moving along the same trajectory as the spacecraft. So it wouldn't be that difficult for the hab module to either (A) shoot some sort of grappling hook and haul the hab in to safety, or (B) fly back to the ship and dock with the exit hatch. There are small thrusters attached to the hab for just that purpose. You can even see them in the third panel, if you look really close.
Doesn't that use up a lot of energy, spinning the ship like that?
No. Once you get the ship spinning, you don't need to do anything else to keep it spinning. How much energy it takes to get the ship spinning really only depends on how quickly you want to reach the target rotational speed. You can do it quickly with RCS thrusters, or you can do it more slowly using reaction wheels.
Why does a space freighter need a crew? Wouldn't it just be automated? That makes a lot more sense.
I'm glad you asked that question.
So wouldn't they all spill their coffee when the engine fires?
If they fired the rockets while spinning, the acceleration would act like a “second gravity” pulling everything into the walls. Unless it's an emergency maneuver, this would be avoided. In general, you'd want to reel in your habs and de-spin before firing the rockets. I'm not an expert on this stuff, but from my understanding, something about the angular momentum of a spinning spacecraft makes it a lot more difficult to steer and change attitude and whatnot, so you'd want it stabilized for any course corrections and stuff like that.
So you're just not going to answer my question about why they need a crew?
Interestingly enough, NASA actually has tested this concept of using the space tether “spinning bola” technique to generate artificial gravity. The 1966 Gemini 11 mission deployed a tether from the space capsule and fired their side thrusters to create a slow controlled spin. The artificial gravity felt by the astronauts on board the capsule was very little (only about about 0.00015g), but that was because it was a relatively short tether and not a high rotation rate. But it did prove the concept works.
That's all for today, folks. Tune in for the next installment, which should drop on Friday. Or maybe Saturday. Sunday maybe? Some time in the future. And I'll see you then!
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