Mummies on Mars
All this is why Connor and Passalacqua agree: A body on Mars, if left outside or even buried in the loose martian soil, would probably dry out and mummify.
The first few stages — algor mortis, livor mortis, and rigor mortis — would still take place, Connor says. But there might be almost no other overt signs of decomposition, she adds. Autolysis and putrefaction would continue until the body froze, with one significant caveat: Most of the bacteria in our body are aerobic, meaning they need oxygen to function. On Mars, only the anaerobic bacteria that don’t require oxygen could proliferate until freezing, which means putrefaction would be severely limited.
After freezing, the body would dry out as its moisture sublimated away, leaving a well-preserved, natural mummy behind, the likes of which might have made the ancient Egyptians jealous. “The desiccated tissues would likely be very stable for an indefinite period,” Connor says.
“If you think about those peat bog bodies from the Medieval period, I would assume it would be kind of like that,” Passalacqua says. Those bodies — also remarkably well preserved — are mummified in part because peat bogs are oxygen-poor environments, which again limit the body’s own breakdown and prevent most organisms from coming in and finishing the job.
“If you think about a body going from something that looks like a person to something that looks like a skeleton, I don’t think you’re really going to get that in [the martian] environment. [Bodies] might dry out and mummify, but I don’t think much else would change,” Passalacqua says.
Dust to dust?
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. “That’s a huge amount of energy that’s just wasted to burn a body and not use for anything else,” Passalacqua speculates. After all, “you’re in this weird Mars environment, you probably want to be as economical as possible in all things.”
But both burial and cremation have a significant downside: the loss of potentially precious biomass. Remember that on Earth, decomposition is the ultimate recycling program, returning that biomass to the environment. “The environment that we’re in [on Earth] always wants to exploit [biomass] as much as possible. But the Mars environment’s not going to be able to exploit those resources at all, it’s just going to be lost resources for everybody,” Passalacqua notes.
In a place where bringing your own resources comes with high monetary and physical costs, is that really ideal?
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. “Evolution is ongoing and can happen quickly,” Connor says, noting, for example, the rapid appearance of COVID-19 variants throughout the pandemic. “And so I would not be surprised if something [that we carried from Earth] evolved quickly to take advantage of a new food source, particularly if there was a cemetery of colonists.”
Today, the only remains on Mars are those of defunct robotic missions, sparsely dotting the landscape as they gather layer after layer of rust-red dust. But when humans arrive, there’s clearly a lot we’ll need to plan for — including what to do with our dead.