space squeezes the kidneys

Ever since man first left Earth in 1961, scientists have been obsessed with the effects of space on the human body. We know that microgravity affects our bones, eyes and heart, but the greatest biological obstacle to reaching another planet for the first time is our kidneys.

Largest kidney health study in space. A new study led by scientists at University College London (UCL) suggests our kidneys won’t survive a round trip to Mars. Nor to a long-term stay on the Moon.

Published in the journal Nature Communications, it is the largest analysis of kidney health during spaceflight to date. It includes data from both astronauts and simulated space flights with mice, some of which received the same dose of cosmic radiation that humans would have received during missions to Mars that lasted about two years.

The results are not at all encouraging. The study shows that kidneys become deformed in space conditions. Kidney tubules, responsible for regulating calcium and salt balance, show signs of shrinkage after less than a month in space in both humans and animals.

Until now, kidney stone formation in space was thought to be due to bone loss caused by microgravity, which releases calcium into the urine. However, the UCL team found that microgravity fundamentally changes the way the kidneys process salts, which significantly contributes to the formation of stones.

The role of radiation Researchers attribute this phenomenon to microgravity rather than radiation, although they still don’t fully understand how the two variables interact.

The Earth protects us from cosmic radiation thanks to its magnetic field, but outside of this protective bubble, astronauts are completely exposed to solar winds and cosmic radiation.

The most alarming discovery is that mice exposed to artificial radiation for two and a half years suffered permanent kidney damage and loss of kidney function.

Dialysis on the way back. “If we don’t develop new ways to protect the kidneys during an astronaut’s journey to Mars, he or she may need dialysis on the return trip,” explains Kate Sue, lead author of the study.

Despite the disappointing finding, the study also opens the door to possible solutions. Researchers believe that by better understanding how kidneys behave when exposed to radiation and microgravity, technological or pharmaceutical solutions could be developed to protect kidney function during long-duration spaceflight.

Images | NASA, Chutong Zhong, Zhongwan Li, Peter Gordon and Kate Sue

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