Why kidneys are damaged in space.

According to scientists, astronauts will experience kidney problems for two reasons. The main cause is galactic cosmic rays (GCR), or simply cosmic radiation. Additionally, microgravity has a negative impact. Scientists report this in the journal Nature Communications.

You might think of astronauts who spend extended periods on the ISS without kidney issues. In reality, the ISS is not fully exposed to GCR, as it is located in low Earth orbit under the protection of the Earth's magnetic field. However, even on the ISS, an astronaut receives the same dose of radiation in a year as a nuclear power plant worker does in five years.

Currently, the only people who have been fully exposed to GCR are the astronauts who participated in NASA's Apollo missions, meaning the 24 individuals who went to the Moon. However, these journeys never lasted longer than 12 days. A mission to Mars would require spending several years in space. As a result, astronauts would receive an enormous dose of radiation.

What happens to the kidneys in space?

As mentioned earlier, scientists have previously determined what happens to blood in space and human DNA, as well as other body systems. For example, researchers recently discovered a phenomenon known as "space migraine," which astronauts seldom discuss. However, kidneys have not received much attention. Therefore, it was not anticipated that these organs could be severely damaged by radiation.

In a recent study, scientists analyzed kidney function and related biomarkers in more than 60 astronauts. Additionally, they thoroughly examined the kidneys of rodents that had been on the International Space Station (ISS). They also simulated the effects of long space journeys by bombarding mice and rats with a dose of radiation similar to what astronauts would receive during a trip to Mars.

As it turns out, serious changes in the kidneys can occur in astronauts in less than a month of being in space. These changes will lead to progressive and irreversible loss of kidney function. However, astronauts will experience symptoms much later.

The issue is that the kidneys are organs whose problems become noticeable only in the later stages. For example, kidneys can lose 75% of their function without a person feeling any symptoms, or symptoms may just begin to appear. Therefore, it is quite possible that astronauts will feel health problems not in space, but upon returning to Earth, and these issues will be irreversible. In fact, they could become disabled.

But that's not all—another problem is the formation of kidney stones, and astronauts will face this issue much earlier than kidney failure. Scientists have long known that the risk of developing kidney stones in space is 14 times higher. Previously, this problem was associated with bone demineralization due to microgravity. Now, however, scientists believe that kidney failure, which gradually develops in astronauts, is partly to blame.

People won't be able to fly to Mars?

The conclusions drawn so far are only preliminary, as they are primarily based on experiments with rats in laboratory conditions. If confirmed, long-duration space flights will become impossible without addressing this issue.

It may not be possible to protect the kidneys from radiation, but it is possible that scientists could develop drugs to mitigate its negative effects. However, solutions to other health problems, both mentioned above and less serious ones like nail detachment, have not yet been found. Therefore, a manned flight to Mars is unlikely to take place in the near future.