Ad Astra Per Aspera

I've basically spent the past six weeks trying to characterize the radiation that astronauts would be exposed to in deep space, and develop a model for shielding astronauts from said radiation. I didn't think it would take remotely this long.

Part of the problem is that scientific and engineering researchers are terrible writers. I already knew this, but I'm being viscerally reminded of it every time I try to decipher the notation in some technical paper. I think that technological progress is probably significantly slowed by how opaque many results are, even when the whole point is ostensibly to share those results. I think there's two changes that we need to make here. First, we need to teach actual technical writing. English classes can't do it; we need dedicated technical composition classes. (We also need to beat every professor who insists their students write with passive voice and no pronouns with a stick until they confess the error of their ways.) Second, we need to fix the incentives in publishing that lead to prioritizing publication volume of quality. (I don't think there's a violent solution here; we're gonna have to do p o l i c y.)

That complaint aside, there's a lot of weirdness going on under the hood. Even if writers could communicate their positions clearly, many of them are using different figures of merit and reaching different results. Just combing through that to figure out the true shielding efficacy of aluminum versus water against galactic cosmic rays would be time-consuming enough.

When I picked out this topic, I thought it would be too easy. Just scale the shielding with mission length to hold exposure constant—easy, right? As if. As it turns out, there's a lot of complications here and the equations are anything if linear. I'm going to pick a half-value thickness for aluminum-cum-water shielding today and run with that, because otherwise I'm going to get stuck in analysis paralysis. My thesis isn't going to permanently settle any questions about manned Mars missions; it's just an engineering exercise to explore the design space and prove that I'm smart enough to hire. After all, getting a job is the whole reason I'm still a student.

I think I figured out where the propulsion engineers were getting the weird flight performance equations I complained about in Reconcilable Differences. Specifically, I'm finding very similar forms of the equations in a NASA translation of Walter Hohmann's The Attainability of Heavenly Bodies, which laid out many of the equations for designing interplanetary space missions.

I'm glad that I found where they were coming from (probably), but I'm still a little bothered, because these forms of the equations aren't really the best to work with. They made a lot of sense in the 1920s and 30s, when astronautics was still an embryonic art. They don't make much sense now, when all the tabulated values one would need for the friendlier forms are available from textbooks or Wikipedia.

To me, this implies a necessity of distancing ourselves from technical source materials, of improving on it whenever possible. The challenge is that the reasons for a particular formulation are not always stated clearly, introducing uncertainties about whether a particular adaptation is valid. Avoiding this, as I have stated, is one of the major goals of my own technical writing. If only industry-standard textbooks took the same care!