When you die on Earth, you generally know what will happen to your body, even if you'd rather not. But what happens to it if you die in space, on Mars, or on the way to Mars?
First off, there aren't really any official protocols in place for what happens to your body when you die in space. NASA's official policy, sent as a statement to Popsci, is that a decision would be made in conjunction between NASA leadership, international partners, and flight operations.
According to astronaut and former commander of the International Space Station Chris Hadfield, however, the space agency does run "death simulations" with astronauts looking at these scenarios.
“If someone died while on an EVA I would bring them inside the airlock first,” Hadfield said of his conclusion from the exercise. “I would probably keep them inside their pressurized suit; bodies actually decompose faster in a spacesuit, and we don’t want the smell of rotting meat or off gassing, it’s not sanitary. So we would keep them in their suit and store it somewhere cold on the station.”
Onboard the ISS, the problem could be dealt with relatively swiftly: Temporary storage in the cooler part of the ISS, followed by possibly the most awesome hearse collection/funeral cortege in human history. But on longer missions – say, to Mars – other solutions would be necessary.
You could, of course, jettison the body out into space, turning a former colleague into potentially dangerous space debris. This actually goes against a UN space debris mitigation agreement, potentially turning that touching send-off into an international incident.
One alternative proposed by a research team set up by NASA is to attach the corpse, inside a bag, to a robotic arm on the outside of the spaceship. The body would freeze solid, at which point the arm would begin to vibrate the bag for 15 minutes until the brittle body has been reduced to small pieces. Water is allowed to evaporate out of the bag through a vent, leaving the ship with about 25 kilograms (55 pounds) of remains to bring home to Earth.
As Susanne Wiigh-Masak of eco-friendly burial company Promessa told Vice, "Everything on the ship has to be very minimal and carefully weighed and stored. There's not a lot of extra room, so if you have a full-sized deceased body, where are you going to keep it?"
To this end, there would only need to be the same number of body bags as crew members, minus one. As Wiigh-Masak said, the extra bag "couldn’t fill itself".
But what happens to your body if you make it all the way to the red planet, only to die there?
In terms of process, again there isn't much that has been set out – it would likely come down to a discussion between astronauts on the mission and the team back on Earth. NASA takes great care not to contaminate Mars and would prefer that bodies be cremated in order to kill off all Earth microbes.
If that isn't possible – say, on an early mission to the planet – or something happened to the whole crew, it could be that they are buried or left on the surface of Mars.
If you are left on the surface of Mars, you will not decompose as you would here on Earth. If you die during the Martian daytime, your bacteria would begin the normal process of breaking down your body. However, once night hits, your body will freeze and the bacteria will be stopped in its tracks. With no bacteria to decompose you, your soft tissues remain safe and you will start to become a mummy on Mars.
Without the protection of Earth's atmosphere and magnetosphere, radiation would break down your body further, but over a much longer timescale, possibly leaving your bones to find tens of millions of years in the future.