Think back to what the Earth was like a thousand years ago — the year 1,015. Almost everything would be foreign to modern eyes and ears — even the language would be incomprehensible. For all intents and purposes, humanity from a millennium ago may as well be an alien species (culturally, at least) with similar DNA, which simply happens to have lived on the same planet we do now.

Now, imagine that these long-gone ancestors had something critically important to tell us — to warn us about. Something they buried deep underground which, if we were to dig it up or otherwise come into it, bad things could happen. Very bad things.

As it turns out, that’s a very real problem. The only difference, though, is that it’s not our problem. It’s the future’s.

Nuclear power plants and atomic bombs, beyond their inherent immediate dangers (more so for the bombs, of course), also create a secondary problem — radioactive waste. If people are exposed to this byproduct of nuclear energy, bad things happen — genes mutate, cancer thrives, and tissue falls apart. So we take our nuclear waste and put it in places away from where there are people — places like the Waste Isolation Pilot Plant (WIPP) in New Mexico. WIPP is as close to the middle of nowhere that somewhere can be (here’s a map), and for good measure, the millions of cubic feet of waste aren’t just sitting in a warehouse there. It’s all buried underground, at a location specifically chosen to have as little of an impact on our health and environment as we can determine. As safe as can be, at least for now — and probably for the next few hundred years.

But let’s fast forward 1,000 years from now. The language, culture, and knowledge of today’s world may not survive that long — but the dangers of that radioactive waste almost certainly will. (Most experts think that the radioactive waste will be harmful for much, much longer — tens of thousands of years — but by then we’ll all have been assimilated by the Borg anyway.) In order to keep the people of the future safe from the radioactive goop created today, we need a way to tell them to watch out. And more likely than not, very few aspects of today’s society will be around to do that. Even a sign warning travelers of potential dangers would be insufficient — who among us could translate runes from the Middle Ages?

In the 1980s, the Department of Energy and a construction company called the Bechtel Corporation created a blue ribbon panel to find a solution. Officially called the “Human Interference Task Force,” the group was made up of various experts ranging from anthropologists and linguists to nuclear physicists and science fiction authors. Everything was on the table — and the results were at times, out of this world.

The most prominently known idea was something called the “Atomic Priesthood.” As Mental Floss explained, the Priesthood was envisioned as a Vatican-styled attempt to institutionalize the knowledge, keeping the true nature of the threat a secret which is only known to those in the inner circle. The Priesthood would communicate the dangers to everyone else through legend, creating mythical stories about radioactive sites with the intent of scaring away anyone who would dare venture within.

But there were other ideas — arguably, crazier ones. A second one also employed superstitions, but in the form of “ray cats.” In the words of Gizmodo, these cats were “creatures bred to change color in the presence of radiation—like walking, purring, yarn-chasing Geiger counters.” Gizmodo further noted that the science would have a cultural element as well — society would create “a body of folklore, passed on through proverbs and myths to explain that when a cat changes color, you better run.”

And finally, some advocated for putting the message on the face of a satellite which, like the Moon, would be visible every night — the persistence of the message would, in theory, ensure that its meaning not get lost over time. Of course, launching an artificial moon into orbit isn’t the easiest thing to do, nor is it aesthetically pleasing.

In the end, none of these ideas were put into practice — at least not yet. Officials plan to keep the WIPP site in service for decades and the locations of other sites are still very well known, so there’s time to find a solution.

Bonus Fact : Perhaps the most polluted place on earth is Lake Karachay in the Ural Mountains. For decades, the lake was used by the Soviet Union as a dumping ground for waste from nuclear weapons. According to Wikipedia, some parts are so radioactive that a 30-minute exposure could be fatal.

From the Archives : Nuclear Shadows: The eerie images left behind from the atomic bombs dropped on Japan.

Take the Quiz : Can you name the countries that have at least one operating nuclear reactor?