A Mission to Mars Could Destroy Astronauts’ Kidneys

Mars has a kidney problem, and scientists are going to have to solve it before we can send any astronauts there. To date, the farthest any person has traveled is to the vicinity of the Moon, about a quarter of a million miles from home. The 12 people who have walked on its surface have gone right up to the edge of human exploration, but there are three others who have gone farther than anyone else.

The crew of Apollo 13 –– Jim Lovell, Jack Swigert, and Fred Haise –– famously didn’t touch down on the lunar surface like they’d planned. Instead, they swung around the far side of the Moon in their broken spacecraft, using the lunar gravity to slingshot them back toward Earth. They orbited at an altitude of 158 miles above the Moon’s surface, at a total distance of 248,655 miles from Earth.

That’s the farthest anyone has been but, in the future, if we have our way, humanity will crush that record by going first to Mars, and later into interstellar space. The fictional crew of The Ark (Season 2 premieres on SYFY beginning Wednesday, July 17), traveling to the next-nearest star only 4.2 light-years away, would experience significant challenges to their survival even if absolutely nothing goes wrong. Recently, an international team of researchers determined that a real-world 2-year roundtrip to Mars and back might cause fatal kidney damage in any passengers.

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Martian Astronauts Could Experience Kidney Failure on Their Way Home

We’ve known since the Apollo era that spaceflight comes at a cost to the body. Astronauts regularly experience bone and muscle loss, vision problems, kidney stones, and other health issues as a result of exposure to microgravity and higher than normal doses of radiation. All of our current crewed space activities happen in low Earth orbit (LEO), about 250 miles above the surface of the Earth. From that relatively close vantage point, astronauts still receive some protection from the Earth’s magnetic field. Astronauts won’t have the benefit of that field once they venture out into deep space.

In a new study published in Nature Communications, researchers performed biomolecular, chemistry, and 3D tissue analysis using samples and data sets from 40 LEO missions involving humans and mice, and 11 laboratory simulations using mice and rats. In seven of those simulations, mice were exposed to galactic cosmic radiation (GCR) doses equivalent to about two years in deep space, comparable to what astronauts would experience during a Mars mission. Each of them suffered severe kidney damage.

Increased risk of kidney stones in astronauts has so far been laid at the feet of bone loss. As the bones break down, extra calcium gets dumped into the urine and builds up in the kidneys. Stay in space long enough and you’ll start literally urinating your own bones. The new study suggests that damage to the kidneys also contributes. Exposure to simulated space conditions caused the kidneys to remodel themselves, shrinking structures which balance calcium and salt in the body. It’s not a huge problem in short-duration missions or those close to home, but a 2-year mission to Mars is likely to cause loss of kidney function and permanent damage.

“If we don’t develop new ways to protect the kidneys, I’d say that while an astronaut could make it to Mars they might need dialysis on the way back. We know that the kidneys are late to show signs of radiation damage; by the time this becomes apparent it’s probably too late to prevent failure, which would be catastrophic for the mission’s chances of success,” said study author Dr. Keith Siew, in a statement.

Unfortunately, GCR can’t be effectively shielded against. Particles from deep space are so energetic that they punch right through even dense materials like metals. Punching through your squishy body is barely an inconvenience. Even worse, particle interactions between GCR and shielding materials could knock neutrons and protons free, causing a cascade which actually makes radiation worse, according to NASA.

This discovery presents a pretty significant hurdle to the pursuit of human space exploration, but it’s one scientists are confident they can solve. People all over the world are working right now to develop new shielding methods, space weather prediction tools, and even pharmaceutical solutions to better protect space crews. We’re going to get there eventually, and it’s best that we identify these potentially fatal problems before we make the attempt.

Season 2 of The Ark premieres on SYFY beginning Wednesday, July 17 at 10/9c. Catch up on the entirety of Season 1, streaming now on Peacock!