How can I lightly irradiate 30,000 km² for just 3 generations?

Question

In the book i'm currently working on, the main protagonist has a special (yet unknown himself) mutation because his ancestors have been involved in nuclear disasters while their mother was pregnant. more precisely: his grandmother was conceived a few months before Chernobyl, in Pripyat. After the Soviet Union dissolved, she managed to escape to Fukushima, and was pregnant with the protagonist's mother during the incident there. The mother then moved then moved to Belgium, and was in Antwerp during a terrorist attack on Doel around 2034, when she was pregnant with the protagonist.

He ends up on a kinda futuristic version of Earth, with Belgium being the global powerhouse. Most of this was caused due to the inhabitants of Belgium having had similar radiation back around 100 BC or something like that, basically when they were being invaded by the Roman Empire. The effect of the radiation has faded for about 500 years now, and the radiation itself hasn't been around for over 2000 years. However, the muttaion, combined with a certain chemical in the atmosphere, gives above-average attributes to the person infected with it, explaining why Belgium managed to conquer most of the world.

the problem is that I need to find a way to expose a 30,000 km² area to a constant yet low amount of radiation, that only lasts about 50-70 years (enough for 3 generations to be born), in a way that appears coincidental to casual observers, almost a freak of nature. The idea is that they won't have a method to even know that there was radiation for a while, long enough to make most signs of the radiation disappear, even in the affected people.

The real reason for the radiation is that it's been placed there by a precursor race that has their own goals for humanity, so a solution that can feasibly be done by such a race is preferable.

Basically, what I want to do is expose Roman-Era Belgium to a small amount of radiation for a short timespan, with no way for the Belgae to notice this for at least 1500 years. The method should be doable by an outside force thousands of years in advance.

Answer 1

So you want to expose a small area to significant levels of nuclear radiation over a period of time using natural means?

My suggestion would be to use a mix of the following three things:

• Radon gas - emitted naturally from some rocks, radioactive.
• Natural nuclear reactor
• Mining

So you have a natural underground nuclear reactor and in general a large seam of material with a high uranium content. Mining then exposes the miners to high levels of radiation, but the process brings to the surface large amounts of uranium ore and releases large amounts of Radon.

Widespread mining means that this effect covers a large area and effects everyone living there. Essentially the major industry of the area is mining and as a result the entire population gets exposed.

Answer 2

This sounds a lot like How do I drug a population in the most efficient way?.

The main problem I see is that radiation just doesn't work that way. To my best knowledge, you cannot create a "special kind" of radiation that will cause particular mutations. You can limit the effect to certain cells by only irradiating those, but most mutations will still not be very effective. Decreasing the power won't make it any more effective; it'll just make both harmful and non-harmful mutations less common.

Disregarding that, my suggestion would be to put it in the water. It's the easiest place to rapidly start adding a substance to, either by adding something to the wells or modifying the rain (if you have the technology). In a case like this, you can get the radiation to become fairly insignificant by the time humans can measure it by choosing an isotope with a suitable half-life. Water with Tritium, refreshed every five or so years, could work wonders on your population.

Alternatively, you could make a whole in the ozone layer. That would increase radiation, and people at that time would likely notice little else than "being in the sun makes you sick". I am not sure what would have to be done to recover it later.

For the "thousands years in advance" part, you're going to have some logistic issues. Robots that manufacture and distribute whatever it is you need and then self-destruct are probably the best option.

As an alternative that takes that into account, they could have launched a spaceship containing a radioactive compounds at speeds near that of light. If it were to keep going at that speed and crash back into the Earth, far less time will have passed for it than for the planet, which would mean that rapidly-decaying particles wouldn't have decayed yet. This could then be written off by the Romans as a meteorite impact.

Answer 3

How important is it to you that the mutations arise by radiation? There are many other means for a precursor race to edit the genome of a population without relying on generating random mutations.

A retrovirus, properly engineered, would be capable of infecting a limited population and inducing any changes to their genomes that could be desired. That could include introducing the desired mutation itself, or weakening the DNA repair machinery to cause the infected people and their ancestors to have an increased rate of mutation even in the absence of radiation or another mutagen.

Otherwise I think your best bet is a giant X-ray/gamma-ray/UV laser on the moon or in orbit. It could simply fire radiation down onto your desired area. Most would be absorbed by the atmosphere, but a large enough laser should be able to increase the mutation rate. This is similar to the hole in the ozone, but a bit more straightforward I think, because you don't have to go back and fix it the ozone after, you can just fly your laser away or self-destruct it.

Answer 4

I like both of Anton's ideas (ozone hole and water supply), but here's an additional possibility: meteorite impact.

If a meteorite contains enough radioactive material with the proper half-life (whatever that may be), it could -- theoretically -- be set on an Earth intercept course by an advanced race quite some time before it's impact time. The race doing this may not be able to predict with precision exactly when or where the asteroid will strike (due to accumulation of small, persistent effects like solar radiation pressure, minor gravitational perturbations, etc... which, over the course of thousands of years, will affect the orbit) but it should know that it will strike eventually. This meteorite could explode in the atmosphere, spreading radioactive dust through the atmosphere and across the soil, or it could provide a much smaller (but more concentrated) debris cloud upon impact. This could even be what contaminates the water supply in Anton's scenario. OTOH, statistically speaking, an asteroid is most likely to land in the ocean.

Eventually, the material it contains will decay to a stable isotope. However, the trick here is the whole "set it up thousands of years in advance" coupled with the required short (decades or centuries) decay time. If the half-life is short enough that it mostly disappears over that short of a time span, you would need a very large amount of it to begin with, to ensure that it doesn't entirely disappear before impact. As an example, let's say your chosen material has a half-life of 50 years. So if the impact introduces quantity Q of this material into the environment, then after 50 years, you will only have Q/2 of this material remaining. But 1000 years before the impact, you would need to double this amount for each half life: that's 1000/50 = 20 doublings. So you would need to start with (2^20)*Q = 1,048,576*Q -- over a million times! In other words, if you started out with the entire meteorite being radioactive, less than a millionth of its mass would be radioactive upon impact. Of course, you can choose a longer half-life material, but then it might take longer to clear out of the environment...

Unless it doesn't. It's possible that with environmental effects -- wind, rain, erosion, etc --- the contaminated material might be dispersed into a wider environment (e.g. running off into the ocean), causing it to become less concentrated and therefore less dangerous. This would allow you to use a much longer-lifed isotope (and thus set things in motion long before hand), but without knowing where the meteorite would land, it would be difficult to predict how long this flushing effect might take.