Look, I get it, those of you know about Gunbuster want to hear about the astrophysics, not the biology, and I do plan to attempt to do the astrophysics of Gunbuster. What you guys have to remember is that I am a biology teacher not an astrophysicist, and astrophysics breaks my brain and calculator. As for the rest of you who wonder just what the heck Gunbuster is, it is the directorial debut of Hideki Anno, famous for creating the iconic Neongenesis Evangelion. Gunbuster is a 6-episode OVA that was released in 1988, and it has all of the classic elements of 80’s anime. It also holds up surprisingly well, and I would go as far as to say that the facial expressions are better than a lot of what we see in today’s anime. As for the plot, it is fairly simple: giant space monsters threaten Earth, so the Earth (aka Japan) builds a super robot to fight them. As a result, most of the series takes place in space and a main element of the show is the effect that time dilation via travel at or near light speed has on the main characters. I promise to try and dig into time dilation, but first let’s take a look at the biology of Gunbuster.
The first and most obvious topic and perhaps the easiest to look at is the giant space monsters that are the antagonists of the series. Given that Gunbuster is only 6 episodes long, not much time is given to them beyond the fact that they are huge, want to exterminate humanity, and reproduce inside young stars. The giant monster part I have already discussed in a previous post on the Vajra of Macross Frontier found here. As for the reproducing inside of young stars…. Yeah, I’ve got nothing to explain that one. Stars are literally giant balls of nuclear fusion, and I can’t think of any remotely possible biological system that could survive in that kind of environment.
Space Radiation Sickness
The second, and dare I say more important plot point, is Commander Koichiro Ohta (aka Coach)’s injuries and illness. The injuries are predictably from a battle that takes place before the series begins. The illness is left unspecified until episode 5 when Noriko and Kazumi discover that he has something called space radiation sickness after he falls coughing up blood. First things first, there is no such thing as space radiation sickness; that being said, there is a ton of radiation in space and it is something that astronauts and high-altitude pilots need to protect themselves against. For example, a 6 month stay on the International Space Station is an exposure over ten times the amount of radiation the average American might experience in 1 year.
To put things another way, astronauts can be exposed to up to 2,000 mSv (millisieverts are a measure of radiation), during a 6-month trip, and your risk of cancer goes up after exposure to 100 mSv.
I think Hideki Anno’s second source of inspiration for space radiation sickness came from the Hibakusha (atomic bomb survivors). There were over 500,000 survivors of the bombing of Hiroshima and Nagasaki, and they were in a brief period of time exposed to extremely high levels of radiation similar to, if not greater than, what astronauts face (it depends on the amount of time they spend in space). Those survivors faced and still face a number health effects as a result of their experience. These health issues include much higher risk of cancer, cataracts, reproductive issues (probably why Kazumi never had child with Coach), and an increased risk of certain infectious diseases, just to name a few.
Thus, I think what Hideki Anno is referring to with space radiation sickness is not chronic exposure to radiation, but instead the lingering after-effects of a single event. The technology of Gunbuster is incredibly advanced, so I can’t imagine their ships lacking shielding to block radiation. Additionally, the threat posed by space radiation is never once mentioned and no one other than Coach is suffering from exposure to radiation. Yet, Noriko and Kazumi both know and recognize the situation for what it is. This leads me to believe that this is something that everyone who travels through space knows about, but that it is not a common occurrence.
This leads us to the question of when was Coach exposed to a high dose of radiation, and how he survived past the 6-month time limit he was given in the show. I think the most obvious choice is that he was exposed during the first disastrous battle humanity had with the space monsters and that led to the death of Noriko’s father. A nearly destroyed ship and escape pod is probably not nearly as resistant to radiation as a fully intact ship. On a final note- this is one instance of my theory being proven by the show itself. In the sequel to Gunbuster, Diebuster, Tycho’s buster machine is destroyed and she is exposed to space without her spacesuit on for a short time and is later shown being treated for space radiation sickness, thus proving it is from brief unprotected exposure to the radiation present in space.
Another reason I like this explanation is that it also provides a logical way for Coach to have survived past the 6-month time limit he was given. This limit was probably the result of a terminal cancer, and occasionally people do survive terminal cancer, so it’s not impossible for Coach to have recovered without knowing more about the particular cancer he had.
It’s official, while it might not be called space radiation sickness, over-exposure to radiation is something that astronauts must take seriously as it can have long lasting side effects. I know it’s not much, but this is the first of three posts on Gunbuster. The next two Gunbuster posts will be about the physics, I promise.