A new study led by researchers from UCL has found that space flight alters the structure and function of the kidneys, with galactic radiation causing permanent damage that could pose a threat to any mission to Mars.
The study, which was published in Nature Communications, is the most extensive analysis of kidney health in space flight to date and includes the initial health Data set for commercial astronauts. It is published as part of a Nature special collection of papers on space and health.
Researchers have been aware of the health problems caused by space flight since the 1970s, in the years after humans first traveled beyond Earth’s magnetic field, most notably during the first moon landing in 1969. These problems include loss of bone mass, weakening of the heart and eyesight, and the development of kidney stones.
Many of these problems are believed to be due to exposure to space radiation, such as solar winds from the Sun and Galactic Cosmic Radiation (GCR) from deep space, that the Earth’s mThe Earth’s magnetic field provides protection for those of us on Earth. Because most astronauts travel in Low Earth orbit (LEO) and are only partially shielded by the Earth’s magnetic field, only the 24 individuals who have traveled to the moon have been exposed to unfiltered Galactic Cosmic Radiation (GCR) and only for a short duration of time (6-12 days).
The potential changes in the kidneys and other organs due to the conditions experienced during space travel beyond Earth’s magnetic field for extended periods have not been studied. This study, funded by Wellcome, St Peters Trust, and Kidney Research UK (KRUK), involved a team of researchers from over 40 institutions led by UCL.Researchers from various institutions around the world conducted a series of experiments and analyses to study the effect of space flight on the kidneys. This involved examining biomolecular, physiological, and anatomical data and samples from 20 study groups, including samples from over 40 low Earth orbit space missions with humans and mice, as well as 11 space simulations with mice and rats. Some of these simulations included exposing mice to simulated doses of galactic cosmic rays equivalent to those experienced during 1.5-year and 2.5-year missions to Mars, in order to mimic the conditions of space flight.The study showed that the conditions in space impact both human and animal kidneys, causing specific kidney tubules to shrink after just a month in space. This affects calcium and salt balance regulation. Researchers believe that microgravity, rather than GCR, is the main cause of this, but more research is needed to fully understand the impact of both microgravity and GCR on these structural changes. It was previously thought that kidney stone development during space missions was solely due to bone loss caused by microgravity.The UCL team’s research revealed that space flight fundamentally changes the way the kidneys process salts, leading to a buildup of calcium in the urine and potentially contributing to kidney stone formation. Additionally, mice exposed to radiation simulating deep space conditions for 2.5 years exhibited permanent kidney damage and loss of function. Dr. Keith Siew, the study’s lead author, emphasized the importance of understanding the impact of space travel on astronaut health.The short space missions conducted so far have shown an increase in health issues, such as kidney stones. However, the reasons for these issues and their potential impact on longer flights, like the proposed mission to Mars, are not yet fully understood.
An expert stated, ”If we don’t find new ways to protect the kidneys, astronauts traveling to Mars might require dialysis on the return journey. Kidneys are slow to show signs of radiation damage, and by the time symptoms appear, it may be too late to prevent failure. This would be disastrous for the success of the mission.”The results show significant challenges for a Mars mission, but it’s important to identify the problems first before finding solutions. Professor Stephen B. Walsh, the senior author of the study from the London Tubular Centre, UCL Department of Renal Medicine, emphasized the importance of kidneys in space missions. It’s not possible to shield them from galactic radiation, but with more knowledge about renal biology, there may be technological or pharmaceutical advancements to support extended space travel. Developing drugs is essential for supporting the health of astronauts during long space missions.The development of therapies for astronauts could also have positive effects on Earth, such as helping cancer patients’ kidneys handle higher doses of radiotherapy, as the kidneys are a limiting factor in this treatment. The study only shows the effects on the kidneys up to two and a half years, but it provides the most comprehensive data currently available.
