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Someday, somebody’s going to die on Mars. Death isn’t fun to think about, so let’s just assume it’ll be after one of the founders of the first Mars colony has lived to a ripe old age and watched their people grow and flourish and it’ll all be very peaceful.

But no matter how or why it happens, the science of what comes next is super interesting. First, any burial plans are going to have to consider international law, because there are United Nations charters against contaminating other planets. And unfortunately, we humans are covered in and filled with contaminating microbes.

And if a person is going to die on the Red Planet, all those microbes are going to have to be killed or contained. And there are a couple options for how to do it. The first is cremation, or burning a body into ashes.

Fire will kill all those microbes, and it’s a practice that many communities already use and have rituals around. But there’s also an alternative that’s being developed specifically for use in space! It’s called Body Back, and it’s pretty sci-fi.

In 2005, NASA contacted the Swedish company Promessa, which specializes in environmentally- sound burials and cremations. NASA asked them to look into a system for handling remains that can be used in space. So they came up with the Body Back, which is basically just an adaptation of Promessa’s existing process, although it hasn’t been done to anyone on Earth yet.

First, the body of a Mars traveler would be stuck in a weatherproof bag. It’d be cooled down, and then exposed to liquid nitrogen for a bit. This would deep-freeze the body and make it really brittle.

Then, the bag would be shaken up by a machine until the body became a powder. Which is really effective for saving space, and that’s always important on a mission, even if it’s kinda creepy. Still, liquid nitrogen doesn’t always kill bacteria.

It can also preserve them, causing them to stop growing without actually dying. So the body would have to stay in the bag forever. But it’s at least an option.

Now, if cremation or bag of powder options aren’t available, like if someone’s spacesuit breaks and they’re exposed to the Martian elements, the process would go a little differently. For one, they’d technically be violating international law, but there would be more immediate problems at that point. To know how a body would respond to being left alone on Mars, scientists can actually study a similar environment on

Earth: the Atacama desert in Chile. The Atacama is one of the driest places in the world, and it’s super high up, with peaks reaching elevations of about 6000 meters. And the higher up you are, the thinner, cooler, and drier the air. It’s a little like Mars.

Hundreds of years ago, the Atacama was a part of the Incan empire, and the Inca had a practice called capacocha. These were ritual child sacrifices, which, to be clear, are horrible, but the bodies of these children have helped scientists with research hundreds of years later. Because, despite all that time, the bodies haven’t really decayed.

In the Atacama, it’s too cold and dry for bacteria to grow well, so the bodies became natural mummies. And that’s close to what would happen on Mars, too. It’s generally colder and drier than it is on Earth, so not much would happen.

The bacteria on or in someone’s body just wouldn’t grow, or would grow much more slowly, so it would take centuries for a body to break down, if it decayed at all. Now, if someone died closer to the Martian equator, where the temperatures can get up to 20 degrees Celsius, the bacteria inside their body might start to decompose it for a while. But the process wouldn’t go on forever.

That’s because Mars also has super high levels of bacteria-killing radiation that would finish the job. You’re probably familiar with UVA and UVB radiation from sunscreen and sunglasses labels, but Mars also has an extra kind: UVC, which has a shorter wavelength. Our atmosphere is capable of filtering out all UVC radiation, so life on Earth isn’t great at dealing with it.

UV-C is also especially deadly, because those shorter wavelengths carry a lot more energy. So it would probably kill most of the surviving microbes. So if someone died on Mars and there was no way to recover the body, or turn it into a powder, it would probably become a mummy over thousands of years.

Admittedly, there is a chance some of those bacteria could survive the UVC radiation, thanks to certain mechanisms that can repair radiation damage. If they did, they would probably decompose the body over time. But then Mars would be home to a bunch of radiation-resistant bacteria, which is a whole new problem.

Or horror movie. And that’s probably why the United Nations would require bodies to be sterilized or contained. Thinking about people dying on Mars isn’t exactly something NASA or any other space agency really wants to do, but it’s an important part of planning for the future.

And even if it is a little morbid, the science behind it is definitely worth thinking about. Thanks for watching this episode of SciShow Space! If you’ve ever wondered what would happen if someone died in the vacuum of space, we’ve actually talked about that, too.

You can watch our episode all about it over at the main SciShow channel. [♪ OUTRO].