We’re getting so close to the premier of Rogue One that my coworkers and I are paranoid we’ll be confronted by our bosses. We huddle around the microwaves a little too early during lunch, eyes wide with childish wonder, giddy over X-Wings, Alderaan, and the Death Star. Every few minutes we hush ourselves after realizing our voices have gotten a tad too loud.
Nika Howard and I had more questions for Dr. Karen Yu, who answered a few of our questions last time. This time we go into how humans would cope in a Star Wars universe and how strong an AT-AT’s stomp is!
Alan: What do you think it would be like to run underneath AT-ATs? Would you be able to considering the force of impact those legs would have?
Dr. Yu: Let’s assume that the AT-AT has the same density of an M1 Abrams tank of about 0.76 tons/m3. I can’t say if they are using lightweight materials, or if they’re reactor is extra heavy, so this is a guess. If we draw a rectangular box around the AT-AT minus the head and just divide by 2 for the empty space between the legs, we get that it has a mass of about 400 tons. I believe the technical manuals say it can carry up to 1 ton of troops and other stuff, and it looks pretty loaded up, so we get a total mass of 401 tons. Now I have to say here that this mass is a COMPLETE guess, as a quick search from online reveals masses from 200 tons to over 2000 tons and nothing from any official sources.
Looking at the trailer, the leg moves about 1 m, and it takes about half a second, giving us 2 m/s. Now we plug it into Fd=1/2*mv2, where we assume that it makes a 0.1 m indent in the ground (a guess looking at pictures of AT-AT footprints on the internet) and divide by 4. Assuming that only 1/4 of the mass is making the impact, we get around 4 MN, which is about twice the thrust of the main shuttle engine at lift off. If we look at the energy, we have about 200 kJ which is less than a 1.0 on the Richter scale, so fairly insignificant for the Earth. It is, however, similar to the energy released from 2 hand grenades, which I think is probably enough to knock all but the most sure-footed people on their bum.
Now, there are quite a lot of assumptions made here, including how much distance is traveled before the leg stops, the mass of the AT-AT, whether or not it uses a system where the centre of mass is shifted to the other 3 legs while this one is in motion, the type of ground it’s stepping on (marsh, concrete, etc.), and so on! So please do take this calculation as an imprecise estimate!
Nika: What consequences would the modes of travel used in Star Wars have on the human body and how would the human body have to adapt to survive in the Star Wars universe?
Dr. Yu: If I recall from the expanded universe books, the ships in Star Wars have access to what they call inertial dampeners which help mitigate the effects of high acceleration. If that’s the case, flying an X-wing or TIE fighter could potentially be less stress on the body than flying an F-22 is today. I believe the books also mention artificial gravity, which makes sense looking at how easily everyone walks around on the Falcon even when it’s not moving in space. Given this, space travel in Star Wars is most likely a very comfortable experience due to the technology they have, and potentially wouldn’t feel like they are moving at all (might cause motion sickness if you look out the window!).
As an example of what space travel might be like without the luxurious technologies of the Star Wars universe, we can look at The Expanse, whose travelers aren’t lucky enough to have inertial dampeners and artificial gravity. Given high enough acceleration, your heart can’t effectively pump blood to your brain, which is why people pass out in high G maneuvers. With a high enough sustained acceleration, this could easily kill someone. In The Expanse, a fluid is pumped into their bodies to counteract this effect. I’m not a biologist, but I can certainly see requiring something like this to ensure that we can handle the high accelerations needed to make space travel shorter time-wise. As for gravity, without the ability to generate this artificially, you’d need to use acceleration and centripetal force to simulate the effects. Now in many cases, this will mean you cannot get the gravity as high as we have on Earth. So you have people growing up in these environments with abnormally long limbs and bodies who aren’t able to stand on their own feet when they enter a real gravity well. This is, of course, pure conjecture, but quite possible for a person who lived their entire life in a low G environment. At present, muscle atrophy is a serious issue for our astronauts on the ISS. Here’s a recent report from NASA talking about how current measures of exercise that the astronauts do aren’t enough to prevent injury upon their return.
Star Wars also has shields, which is great, because once we’re out of our atmosphere, we are exposed to quite a lot of solar radiation. In fact, airplane pilots and stewards/stewardesses are radiation workers because they are constantly exposed to more solar radiation simply because they’re in the air and have less atmosphere for the radiation to attenuate through. Similarly, the Earth’s magnetic field deflects a lot of the energetic cosmic rays, which wouldn’t happen if you’re far out from a plant. Without shielding you are likely to see higher incidences of cancer and other diseases caused by radiation among those conducting long term space travel. Here’s another report from NASA talking about this for any potential manned Mars missions.
That’s all from Dr. Karen Yu. You can see her talk a bit more about Star Wars here. Thanks for all your help, Dr. Yu! You’ve given us some fantastic insight.
See you at the theaters on Thursday, December 15th!