Ask Us Anything: What happens to your body when you die in space?

And should colonists on Mars be allowed to eat each other?
astronaut on spacewalk
Though they don't like talking about it, NASA astronauts do prepare for death of a crewmate. NASA

ON JULY 21, 1969, when the Apollo 11 crew was due to depart the lunar surface after a 22-hour visit, two speeches were placed on President Richard Nixon’s desk. “Fate has ordained that the men who went to the moon to explore in peace will stay on the moon to rest in peace,” read the contingency speech. Would Buzz Aldrin and Neil Armstrong live out the rest of their days staring at the blue glow of Earth from 250,000 miles away?

We’ve lost only 18 people in space—including 14 NASA astronauts—since humankind first took to strapping ourselves to rockets. That’s relatively low, considering our history of blasting folks into space without quite knowing what would happen. When there have been fatalities, the entire crew has died, leaving no one left to rescue. But as we move closer to a human mission to Mars, there’s a higher likelihood that individuals will die—whether that’s on the way, while living in harsh environments, or some other reason. And any problems that arise on Mars—technical issues or lack of food, for example—could leave an entire crew or colony stranded and fending for themselves.

No settlement plans are being discussed at NASA (leave those to pie-in-the-sky private groups like Mars One for now), but a crewed mission has been on the docket for some time, and could touch down as early as the 2040s. NASA’s “Journey to Mars” quotes an estimated three-year round-trip, leaving plenty of time for any number of things to go wrong.

“The real interesting question is, what happens on a mission to Mars or on the lunar space station if there were [a death],” says Emory University bioethicist Paul Wolpe. “What happens when it may be months or years before a body can get back to Earth—or where it’s impractical to bring the body back at all?”

Today’s astronauts travel to space by way of the Russian Soyuz, then spend a few months on the International Space Station. Because astronauts are in impeccable health at the time of launch, a death in the ISS crew would likely result from an accident during a spacewalk.

“In the worst case scenario, something happens during a spacewalk,” says Chris Hadfield, Canadian astronaut and former commander of the ISS. “You could suddenly be struck by a micro-meteorite, and there’s nothing you can do about that. It could puncture a hole in your suit, and within a few seconds you’re incapacitated.”

This hypothetical astronaut would only have about 15 seconds before they lost consciousness. Before they froze, they would most likely die from asphyxiation or decompression. 10 seconds of exposure to the vacuum of space would force the water in their skin and blood to vaporize, while their body expanded outward like a balloon being filled with air. Their lungs would collapse, and after 30 seconds they would be paralyzed—if they weren’t already dead by this point.

The likelihood of death on the ISS is low, and it’s never happened before. But what would surviving astronauts do if it did?

Prepare for the Worst

ISS and shuttle astronaut Terry Virts served two expeditions on the space station and one mission on the space shuttle. In total he’s clocked 213 days in space. But the astronaut says he’s never been trained to handle a dead body in space. “I did quite a bit of medical training to save people, but not for this.”

NASA’s official statement to Popular Science on the subject left a lot to be desired:

“NASA does not prepare contingency plans for all remote risks. NASA’s response to any unplanned on-orbit situation will be determined in a real time collaborative process between the Flight Operations Directorate, Human Health and Performance Directorate, NASA leadership, and our International Partners.”

“In my 16 years as an astronaut I don’t remember talking with another astronaut about the possibility of dying,” Virts says. “We all understand it’s a possibility, but the elephant in the room was just not discussed.”

But NASA’s out-of-sight-out-of-mind policy on death may not be the norm. Commander Hadfield tells Popular Science that all international partners who train for missions to the ISS (including JAXA and ESA) do in fact prepare for the death of a crewmember.

“We have these things called ‘contingency simulations’ where we discuss what to do with the body,” he says.

Hadfield discusses these ‘death simulations’ in his book An Astronauts Guide to Life. He sets the scene—”Mission control: ‘we’ve just received word from the Station: Chris is dead.’ Immediately, people start working the problem. Okay, what are we going to do with his corpse? There are no body bags on Station, so should we shove it in a spacesuit and stick it in a locker? But what about the smell? Should we send it back to Earth on a resupply ship and let it burn up with the rest of the garbage on re-entry? Jettison it during a spacewalk and let it float away into space?”

As Hadfield points out, a corpse in space presents some major logistical problems. The fact that a dead body is a biohazard is definitely the biggest concern, and finding the space to store it in is a close second.

Since NASA lacks a protocol for sudden death on the ISS, the station’s commander would probably decide on how to handle the body. “If someone died while on an EVA I would bring them inside the airlock first,” Hadfield says. “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.”

If submarines lose a crew member and can’t make it to land right away, they store bodies near the torpedoes—where it’s cold, and separate from the living quarters. The crew of the ISS already stores trash in the coldest spot on the station; it keeps the bacteria away from them and makes smell less of an issue. “I would probably store them in there until a ship was going home, where they would take the third seat on the Soyuz,” Hadfield says. They could also store a body in one of the airlocks.

Freeze-Dried Funerals

NASA may not have specific contingency plans for a sudden death, but the agency is working on it; in 2005 they commissioned a study from Swedish eco-burial company Promessa. The study resulted in a yet-to-be-tested design called “The Body Back.” The creepy-sounding system uses a technique called promession, which essentially freeze-dries a body. Instead of producing the ash of a traditional cremation, it would turn a frozen corpse into a million little pieces of icy flesh.

During the study, Promessa creators Susanne Wiigh-Masak and Peter Masak collaborated with design students to think about what this process might look like while en route to Mars. On Earth, the promession process would use liquid nitrogen to freeze the body, but in space a robotic arm would suspend the body outside of the spaceship enclosed in a bag. The body would stay outside in the freezing void for an hour until it became brittle, then the arm would vibrate, fracturing the body into ash-like remains. This process could theoretically turn a 200-pound astronaut into a suitcase-sized 50-pound lump, which you could store on a spacecraft for years.

body back for space funerals
The “Body Back” could provide astronauts frosty funerals. Promessa

If freeze-dried cremation isn’t an option, you can always “jettison” the body out on a forever path into the void. While the UN has regulations about littering in space, the rules may not apply to human corpses. “Currently, there are no specific guidelines in planetary protection policy, at either NASA or the international level, that would address ‘burial’ of a deceased astronaut by release into space,” says Catherine Conley at NASA’s Office of Planetary Protection.

But the laws of physics might trump the laws of humankind on this one. Unless we strapped a mini rocket to the deceased, they would end up following the trajectory of the spacecraft from which they were ejected. As the years went on and the bodies accumulated, that would make for a morbid trip to and from Mars.

Martian Burial Rituals

But the risks of dying along the way are nothing compared to the inevitability of dying once you get there. In promoting his own future space settlement plans, SpaceX’s Elon Musk has openly cautioned that, “If you want to go to Mars, prepare to die.” Which begs the question: if someone dies on the Red Planet, where do you put them?

If someone were to perish on the spaceship en route to Mars (or beyond), cold storage or a round of promession could be a fine solution. But there isn’t a morgue on the surface of Mars, and spaceships are usually low on extra space.

So what would Martian explorers do with a body? “I would expect that if a crew member died while on Mars, we would bury them there rather than bring the body all the way home,” Hadfield says.

That makes sense because of the long journey back, but it poses some potential contamination problems. Even the rovers exploring Mars are required by law not to bring Earth microbes to their dusty new planet. Spacecraft are repeatedly cleaned and sanitized before launch to help protect potentially habitable locales from being overtaken by intrepid Earthly microbes. But the bugs on a rover are nothing compared to the bacteria that would hitch a ride on a dead body.

This makes the issue of planetary protection even more nuanced, but a Martian graveyard might not be so far-fetched. “Regarding the disposal of organic material (including bodies) on Mars,” NASA’s Conley says, “we impose no restrictions so long as all Earth microbes have been killed—so cremation would be necessary. Though planetary protection does require documentation of disposal, to ensure that future missions are not surprised.”

But not everyone who dies in space will be treated like inconvenient cargo. Some of those corpses will actually save lives.

Worst Case Scenario

Space may be the final frontier, but it wasn’t always that way. Humans have spent millennia traversing difficult landscapes and putting themselves in bizarre and dangerous situations in the name of discovery. Thousands of lives have been lost in this pursuit, and on occasion the deceased have actually saved the lives of their comrades. Not through acts of deadly heroism, mind you, but through acts of cannibalism.

Don’t think for a second that this couldn’t happen in space. In the book The Martian, author Andy Weir wrote in a scene (spoiler) in which the Ares crew decides to go back to Mars to save a stranded Mark Watney. Johansen, the Ares systems operator and smallest crew-member (requiring the least amount of calories) on the mission tells her father that the crew has a last-ditch plan to make it to Mars if NASA won’t send them supplies for the trip. “Everyone would die but me, they would all take pills and die. They’ll do it right away so they don’t have to use up any food,” she explains. “So how would you survive?” her father asks. “The supplies wouldn’t be the only source of food,” she says.

While extreme, the crew’s plan to commit suicide so one member could save Watney is not totally unheard of. “That’s a time-honored tradition,” says bioethicist Paul Wolpe. “People have committed suicide to save others, and in fact religiously that’s totally acceptable. We can’t draw straws to see who we’re going to kill to eat, but there are many times when we’ve considered people heroes who jump on the grenade to save their buddies.”

Wolpe says the school of thought on cannibalism for survival is split. “There are two kinds of approaches to it. One says even though we owe the body an enormous amount of respect, life is primary, and if the only way one could possibly survive would be to eat a body, it’s acceptable but not desirable.”

Mars boasts a landscape so barren and dead, it would put the frozen mountains that drove the famous Donner party to cannibalism to shame. If anything interrupted the mission’s food supply, they’d quickly run out of alternatives.

But no space agency has an official policy on Martian cannibalism—yet.

A Journey Into the Void

Humans have only been traveling to space for a short time relative to our existence, but we’ve been pushing the boundaries of exploration for thousands of years—and we will no doubt continue to do so despite the risks. Every astronaut or space tourist wishing to embark on a journey to Mars will ultimately be forced to grapple with the reality of deaths both sudden and slow.

NASA may never have officially published a contingency plan for the Apollo moonwalkers, but they were prepared to lose the crew. In his biography, Nixon speechwriter William Safire recalled the tenuous Apollo 11 liftoff. “We knew disaster would not come in the form of a sudden explosion,” he wrote. “It would mean the men would be stranded on the moon in communication with Mission Control as they slowly starved to death, or deliberately ‘closed down communication,’—the euphemism for suicide.”

In fact, NASA had planned to shut down communication with the stranded astronauts and issue them a formal “burial at sea.” But even given that morbid hypothetical turn of events, everyone knew they would keep going to the moon. “Others will follow, and surely find their way home,” Nixon’s back-up speech read. “Man’s search will not be denied. But these men were the first, and they will remain the foremost in our hearts.”

Earth rising. NASA

As we enter an age of space exploration sure to be filled with rocket launches and crewed missions, the thought of death looms over every crew-member and decision maker.

Astronaut Terry Virts may never have casually chatted about dying over coffee with his friends, but he knew what was at stake when he launched into space. “I believe that it is worth it, and that any great endeavor will involve risk,” he says. “We consciously accept the unavoidable hazards that we face.”

Like most explorers, shuttle astronaut Mike Massimino is quick to say that the risk is worthwhile. “It’s about increasing our understanding,” he tells PopSci. “I think it’s worth the risk we take. Exploration has always taken lives and I’m sure it always will.”

The realistic options for a deceased crewmember—cannibalism, cold storage in the trash room, being freeze-dried and shaken into a million frozen flakes—lack the dignity we associate with the majestic endeavor of spaceflight. But Wolpe doesn’t think humankind will have a hard time adjusting to the harsh realities of posthumous treatment in space. We already accept that Earthbound explorers may suffer indignities if they die in the field. Wolpe sees Mount Everest as a perfect Earthly analogue for the future Mars missions: when people die, their bodies just stay there. Forever.

planting flag on the moon
We’re forever chasing that next giant leap NASA

Every year around 800 people attempt to reach the summit of the mountain. Every year, some of those people die. And then another 800 people try the next year. These people want to be first, to be the best, to explore something marvelous and rare. And with this determination comes the risk of paying the ultimate price.

“If you climb Everest, you know that if you die you’re being left there,” says Wolpe. There’s no fancy method of cremation on Everest, no respectfully somber place to stow a body, no way to reasonably pick up a corpse for burial back home. Over 200 bodies lay across the mountain, some of them still visible on days when snow cover is light. Everyone who climbs past them is reminded that they’re risking their lives—and their chance at a proper burial—for a chance at reaching the summit. “You just accept that,” Wolpe says. “That’s part of climbing Everest.”