Astronauts’ roundtrip to Mars possible

 Possible effects of a roundtrip to Mars on astronauts health    

Space journeys that stretch far beyond home are on the horizon. Crews heading for Mars will face conditions quite different from those on Earth, and researchers have been working to figure out what might happen to the human body during these extended voyages. Kidneys have been a big question mark. Recent work reveals that these important organs could face more trouble than previously assumed, including a higher risk of stones and lasting damage. The structure and function of the kidneys is altered by space flight, with galactic radiation causing permanent damage which would jeopardise any mission to Mars, according to a new study. The study, published in Nature Communications, is the largest analysis of kidney health in space flight to date and includes the first health dataset for commercial astronauts. Several studies have hinted at health concerns for astronauts ever since humans first ventured outside Earth’s protective zone, but the new findings shed light on why such problems arise in the kidneys.

Researchers have known that space flight causes certain health issues since the 1970s, in the years after humans first travelled beyond Earth’s magnetic field, most famously during the first moon landing in 1969. These issues include loss of bone mass, weakening of the heart and eyesight and development of kidney stones. Dr. Keith Siew from the London Tubular Centre, based at the UCL Department of Renal Medicine, and his colleagues have pieced together a detailed picture of what happens when living beings, human and otherwise, experience space-like conditions for weeks to years. The latest study was conducted under a UCL-led initiative involving over 40 institutions on five continents. The team considered data from 20 different research cohorts and samples linked to over 40 Low Earth orbit missions to the International Space Station, plus 11 simulations with mice and rats. The work is described as the largest analysis of kidney health in spaceflight so far and includes the first health dataset for commercial astronauts. It also involved seven simulations in which mice were exposed to radiation which mimicked up to 2.5 years of cosmic travel beyond Earth’s magnetic field.

It is thought that many of these issues stem from exposure to space radiation, such as solar winds from the Sun and Galactic Cosmic Radiation (GCR) from deep space, that the Earth’s magnetic field protects us from on Earth. As most manned space flights take place in Low Earth orbit (LEO) and receive partial protection from Earth’s magnetic field, few people who have travelled to the moon have been exposed to unmitigated GCR and only for a short time. Nobody has studied what changes might be happening in the kidneys and other organs as a result of conditions which would be experienced during space travel beyond Earth’s magnetic field over longer periods. Current study findings revealed that the structure and function of the kidneys are altered by spaceflight, with galactic radiation causing permanent damage which would jeopardize any long-distance mission.

St Peters Trust and Kidney Research UK (KRUK) funded study, a UCL-led team of researchers from over 40 institutions across five continents conducted a range of experiments and analyses to investigate how the kidneys respond to space flight. Astronauts in Low Earth orbit still benefit from partial shielding by our planet’s magnetic field. Only 24 people, the ones who went to the moon, have been exposed to the full brunt of Galactic Cosmic Radiation for short trips of about 6-12 days. Nobody has ventured on a years-long mission beyond the Earth’s magnetic boundary, so it was unclear how organs might hold up under more extreme conditions. As part of the new study, researchers found that certain kidney tubules, which control delicate balances of salts and calcium, shrink after just a month in microgravity. The kidneys also process salts in a way that increases the likelihood of kidney stone formation. This new insight shifts the focus away from an older assumption that stones in space result mainly from bone loss causing elevated calcium in urine.

The results indicated that both human and animal kidneys are ‘remodelled’ by the conditions in space, with specific kidney tubules responsible for fine tuning calcium and salt balance showing signs of shrinkage after less than a month in space. Researchers say the likely cause of this is microgravity rather than GCR, though further research is required to determine if the interaction of microgravity and GCR can accelerate or worsen these structural changes. The research highlighted that cosmic radiation cannot be fully blocked by typical shielding. When mice were given doses of simulated Galactic Cosmic Radiation equal to a mission length of up to 2.5 years, the animals showed irreversible kidney damage. Some of the key observations point to changes in how the kidneys manage vital minerals, which impacts long-term health during space travel. The primary reason that kidney stones develop during space missions had previously been assumed to be solely due to microgravity-induced bone loss that leads to a build-up of calcium in the urine. Rather, the UCL team’s findings indicated that the way the kidneys process salts is fundamentally altered by space flight and likely a primary contributor to kidney stone formation. If scientists don’t develop new ways to protect the kidneys, any astronaut that makes it to Mars will likely need dialysis on the way home or upon arrival. “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,” Dr. Siew concluded.

Perhaps the most alarming finding, at least for any astronaut considering a three-year round trip to Mars, is that the kidneys of mice exposed to radiation simulating GCR for 2.5 years experienced permanent damage and loss of function. Space agencies have been aware since the 1970s that journeys outside our planet’s natural defences lead to health concerns involving bones, eyes and the cardiovascular system. This new work puts fresh focus on the kidneys. It also highlights the importance of managing both microgravity and radiation, especially with more ambitious missions on the table. “Our study highlights the fact that if you’re planning a space mission, kidneys really matter. You can’t protect them from galactic radiation using shielding,” noted Professor Stephen B. Walsh from the London Tubular Centre, UCL Department of Renal Medicine. “But as we learn more about renal biology it may be possible to develop technological or pharmaceutical measures to facilitate extended space travel.” Dr Keith Siew, first author of the study from the London Tubular Centre, based at the UCL Department of Renal Medicine, said: “We know what has happened to astronauts on the relatively short space missions conducted so far, in terms of an increase in health issues such as kidney stones. What we don’t know is why these issues occur, nor what is going to happen to astronauts on longer flights such as the proposed mission to Mars.” Any drugs developed for astronauts may also be beneficial here on Earth. For instance, by enabling cancer patients’ kidneys to tolerate higher doses of radiotherapy, which is currently an impediment to that form of treatment. 

The authors say that though the results identify serious obstacles to a Mars mission, it is necessary to identify problems before solutions can be developed. Professor Stephen B. Walsh, senior author of the study from the London Tubular Centre, UCL Department of Renal Medicine, said: “Our study highlights the fact that if you’re planning a space mission, kidneys really matter. You can’t protect them from galactic radiation using shielding, but as we learn more about renal biology it may be possible to develop technological or pharmaceutical measures to facilitate extended space travel. Researchers say that pinpointing these risks is a vital first step before reliable solutions can be introduced. The study’s international collaboration suggests momentum is building to safeguard astronauts’ kidneys, and future innovations could reach beyond space missions to help patients on Earth. Experts note that learning how to handle the combined effects of microgravity and cosmic radiation will be key to making ambitious missions safer. With evidence pointing to serious kidney challenges, careful planning will be needed to keep crews healthy on journeys that last far longer than any undertaken before. Though the study only describes what happens to the kidneys up to two and a half years, it is the most comprehensive data available for the time being.