Planning for a funeral on Mars.

Discover magazine discusses an unusual problem we haven’t had to face yet. How will Mars colonists handle their first funerals in an environment where human bodies don’t decompose they way they do on Earth?:

On Earth, the main factor that affects decomposition is temperature, [Western Carolina University forensic anthropologist Nicholas] Passalacqua says.

“Temperature is really an important factor for the things that metabolize — that eat — human tissues,” he says. “So when you think about insects as a primary kind of scavenger of human soft tissues, insect activity is really temperature dependent.”

Temperature is a factor for another reason as well. “Sublimation occurs in freezing environments — the frozen water escapes to gas without going through the liquid form,” [Colorado Mesa University forensic anthropology profesor Melissa] Connor says, the same way wet clothes can still dry hanging outside in the winter. So, in freezing Earth environments where water sublimates and the cold stops processes such as autolysis, “sublimation desiccates remains and creates mummies,” she says.

Mars’ average temperature hovers around –81 degrees Fahrenheit (–63 degrees Celsius), but this can vary widely by location and season. For example, in October 2020, Mars InSight was reporting highs up to 24 F (–4 C) during the warmest part of the day and lows of –140 F (–96 C) at night.

And there is, of course, no liquid water and no known living organisms on the Red Planet’s surface today.

Exceptionally preserved martian mummies might sound like a cool idea. And the easiest and most straightforward option is, indeed, to bury the deceased. However, if human settlements on Mars really take off, cemeteries may require a bit of zoning planning and forethought, as the bodies in them would not decompose, preventing the reuse of plots.

Cremation, while a popular — and space-efficient — body disposal option on Earth, is probably not the best method on Mars. That’s because cremation requires keeping a chamber in excess of some 1,000 F (538 C) for several hours, which in turn requires immense energy input. In an environment where such fuel could be limited, that’s a costly solution.

Perhaps the best choice could be to recycle that biomass, as would occur on Earth. (It’s worth noting, of course, that processes like embalming largely halt decomposition, so all discussion of decomposition on Earth refers to non-embalmed remains.) In that case, it might be best to bury a body not outside in the martian soil, but instead it in a temperature- and moisture-controlled, Earth-like decomposition greenhouse with organisms such as insects and fungi to eventually turn that body into usable fertilizer or soil. Of course, those organisms would need alternative food sources when there are no bodies to consume, Passalacqua adds.

However, there is a scenario that could change all of this: With our aerobic bacteria unable to function, starved of oxygen in Mars’ atmosphere, our anaerobic bacteria could adapt to the martian environment — perhaps making it possible for bodies to decompose after all.