Space is a hostile place. We may have developed the technology to launch astronauts into orbit and bring them home safely, but scientists are still trying to understand how space travel affects human health, especially in the long run.
This is essential before any planned mission to Mars goes ahead, to ensure the health and safety of astronauts aboard those momentous flights.
We already know from astronaut studies – perhaps most famously, NASA’s Twins Study co-starring identical twins Scott and Mark Kelly – that prolonged spacetime affects blood flow to the brain, alters the gut microbiome, increases inflammation, and causes blurred vision, brittle bones, and muscle atrophy.
Studies in mice simulating spaceflight have also suggested that heading into space ages the immune system and damages the brain.
Now, in a massive collective effort, scientists have published a gigantic collection of nearly 30 articles studying the health risks associated with space travel.
The collection represents the largest space biology dataset ever produced and features some heavy analysis of observations of space flies, worms, mice, and of course astronauts.
Some findings reaffirm what we knew about space-related health problems, while other studies provide new insights, clarify previous findings, or have found ways to improve future experiments.
“Although significant progress has been made in understanding over the past decade [the] health risks [of space travel], more research is needed to enable safer human space exploration beyond [low Earth orbit], including lunar, Mars and deep space missions, “write the researchers in a comprehensive review paper addressing the collection.
The health dangers of space travel begin with the G-forces felt by astronauts on takeoff and continue with exposure to dangerous space radiation and microgravity in space.
During the perilous journey to Mars, for example, astronauts will go far beyond Earth’s protective magnetosphere and will be exposed to cosmic radiation during the significant amount of time it will take to venture to our nearest planetary neighbor and return.
For astronauts hovering in low gravity aboard the International Space Station (ISS), the longest stay of any astronaut is currently 437 days. Clearly, we still have a long way to go to truly appreciate what the health risks of long-distance spaceflight might be, and scientists just need to work with the data we have.
Many of the studies published in this compilation have collected or re-analyzed data from previous experiments made available to researchers through open-access data portals such as NASA’s GeneLab platform.
Combining data like this is one way to bolster the resulting analyzes (researchers often try to see if what was found in one dataset is true in another) and maximize the data gathered from expensive space flights.
‘A collective analysis of multiple models and human studies can lead to a more comprehensive understanding of the physiological and human health-related impacts of the space environment,’ the researchers write, explaining their approach.
One study, for example, analyzed data from nearly 60 astronauts and hundreds of GeneLab samples to look for a universal mechanism that links the widespread health changes that have been observed in different genes, cells, tissues, body systems, organs and muscles.
Across the board, the study showed “systemic changes” in the function of mitochondria, which are the energy packets within our cells that convert oxygen and nutrients into energy.
“What we have discovered over and over again is that something is happening with the regulation of mitochondria that knocks everything out,” said Afshin Beheshti, a bioinformatician at NASA’s Ames Research Center.
This could explain the disruptions observed in astronauts’ immune systems and circadian rhythms, the authors write.
Another study compared data from the Kelly twins with 11 unrelated astronauts who spent about six months on the ISS, looking specifically at their telomeres. These are the protective caps on the ends of our chromosomes, which typically erode with age.
Unexpectedly, the researchers found that some of the astronauts’ telomeres lengthened during their spaceflight, but the group generally had shorter telomeres after returning than before taking off.
“Moving forward, our goal is to get a better idea of the underlying mechanisms, what is happening during long-term spaceflight in the human body and how it varies between people,” said Susan Bailey, telomere biology expert. at Colorado State University. “Not everyone responds the same.”
There were also some interesting results from a study that re-analyzed data from NASA’s Twins Study. He suggested that the spike in inflammatory molecules seen in Scott Kelly’s blood when he returned to Earth (after 340 days on the ISS) could be a marker of muscle regeneration rather than an immune response.
These studies are obviously limited by the very small number of astronauts and animals we can send into space – which is where the worms and flies enter. Using these creatures is an easy way to augment space flight experiments, so they’re featured in the papers, too.
A nematode study on the ISS found subtle changes in about 1,000 genes, particularly those related to nerve cell function, while another study, this time with flies, suggested that a long stay in microgravity reduces the strength of their heart. button.
All in all, this collection of documents – the work of some 200 researchers from NASA and other government agencies, universities and aerospace industry groups – makes a solid contribution to our understanding of the health risks of loitering in space.
The complete list of published articles was collected in the journal Cell.