What Happens to the Human Body in Space

**Understanding the Impact of Long-Term Space Travel on the Human Body: A Comprehensive Analysis**

As humanity ventures further into space, with ambitions to return to the moon and even send astronauts to Mars, a critical question arises: how will our bodies cope with the challenges of long-term space travel? Thanks to groundbreaking research, particularly the largest study ever conducted on this topic, we are beginning to unravel the complexities of how the human body adapts—or struggles—to life in space.

### The Kelly Twins Study: Pioneering Research

In 2019, NASA made history by publishing the first-ever space twin study. This groundbreaking research involved identical twins Scott and Mark Kelly, with Scott spending an unprecedented 340 days in space while Mark remained on Earth. This study provided invaluable insights into the effects of microgravity on the human body. Key findings included telomere shortening, changes in gut microbiome composition, and rapid alterations in gene expression. While these results were significant, they also highlighted the need for further research to fully understand the long-term consequences of space travel.

### The 2020 Breakthrough: Expanding Our Knowledge

The year 2020 brought even more advancements with a series of nineteen new studies that built upon the findings of the Kelly Twins study. These studies analyzed data from both Scott and Mark Kelly, as well as measurements from a total of 56 astronauts. Additionally, ten more papers were released in pre-print format, pending publication after rigorous peer review. This represents the largest dataset ever collected on human adaptation to space, offering a comprehensive picture of the physiological challenges faced by astronauts.

### Mitochondrial Dysfunction: A Core Challenge

One of the most significant discoveries from this extensive research is the identification of mitochondrial dysfunction as a core issue in space travel. Mitochondria, often referred to as the "powerhouse of the cell," are responsible for generating energy that powers cellular functions and organ systems. The studies revealed consistent changes in mitochondrial function across various species, including humans, mice, and other animals.

The underlying cause of this dysfunction remains uncertain, but researchers hypothesize that oxidative stress—a damaging process triggered by harmful compounds called reactive oxygen species—plays a major role. This stress is exacerbated by the extreme environment of space, leading to genetic changes that disrupt metabolic pathways. Understanding mitochondrial dysfunction is crucial because it likely underpins many other observed effects on astronauts' health.

### The Liver: A Key Organ Under Siege

The liver emerges as another critical organ affected by space travel. It undergoes more significant changes in gene and protein expression than any other organ during spaceflight. This is due to the liver's essential role in maintaining homeostasis, particularly in filtering blood and adapting to changes in blood composition.

In space, this vital organ must work even harder to compensate for the altered environment. These findings underscore the importance of studying liver function in astronauts to ensure their health both during and after missions.

### Telomeres: A Double-Edged Sword

Telomeres, the protective caps at the ends of chromosomes that prevent DNA damage, also behave unusually in space. Astronauts often experience telomere lengthening while in space, only to see them shorten significantly upon return—a phenomenon observed in Scott Kelly during his year aboard the International Space Station (ISS).

This fluctuation is hypothesized to result from oxidative stress, which places telomeres at risk. Telomeres are essential for preventing chromosomal damage, so their instability could have serious implications for long-term space travelers.

### A Silver Lining: Adaptive Genetic Changes

Not all changes in space are detrimental. Some astronauts exhibit decreases in blood cell mutations during spaceflight, while others show increased levels of genetic tools that help them adapt to radiation and microgravity. These adaptive changes highlight the body's remarkable ability to adjust to extreme environments, offering potential benefits for both space travel and terrestrial medicine.

### Gut Microbiome: A Unique Space Profile

The gut microbiome also undergoes significant transformations in space. Astronauts develop a unique profile of gut bacteria while in orbit, which scientists find fascinating. This change could be linked to altered nutrition, reduced gravity, or other environmental factors in space. Understanding these shifts is essential for maintaining astronauts' health and ensuring missions are successful.

### Broader Implications: Health Beyond Space

The research extends beyond the realm of space travel. The insights gained from studying astronaut physiology have profound implications for human health on Earth. Conditions such as oxidative stress, mitochondrial dysfunction, and circadian rhythm disruption are also relevant to terrestrial medicine, offering new avenues for treating age-related diseases, metabolic disorders, and other conditions.

### Future Directions: Expanding Our Knowledge

As the pool of astronauts becomes more diverse and missions grow longer, scientists will continue to conduct extensive studies. These efforts aim to build a more comprehensive understanding of human health in space and develop strategies to mitigate adverse effects. By doing so, we not only protect the health of those who venture into space but also gain invaluable knowledge that benefits us all.

### Conclusion: A New Era of Space Exploration

The past few years have marked a new era in our understanding of how the human body adapts to life in space. From mitochondrial dysfunction and liver stress to telomere dynamics and gut microbiome changes, these studies paint a complex yet fascinating picture of the challenges—and opportunities—of space travel.

As we push further into the cosmos, this research will be instrumental in ensuring that astronauts can safely and effectively carry out missions. Moreover, it offers exciting possibilities for improving health here on Earth. The future of space exploration is not just about reaching new destinations; it's about understanding ourselves better through the extremes of space.

"WEBVTTKind: captionsLanguage: enAs space travel gets more and more advancedand humanity gets closer to sending people back to the moon — or even sending astronauts to Mars —we need to know how our bodies will handle long-term space travel.And, thanks to the largest study ever published on the topic,we now have a picture that’s coming into focus...and that picture is full of challenges.Back in 2019, NASA published the first ever space twin study.This compared twins Mark and Scott Kelly before, during, and after Scott spent 340 days in space —that’s the longest any U.S. astronaut has consecutively spent in spaceflight — while Mark stayed here on Earth.That study gave us so much insight into how the human body changes in microgravity:from telomere shortening to gut microbiome changes to rapid alteration of gene expression.It also told us there was still so much to learn...and boy, did 2020 deliver.A set of nineteen new studies builds on the results of the Kelly Twins study,reanalyzing some of that data and comparing those results to measurements between 56 astronauts in total.Plus ten more papers are in pre-print now, being reviewed and set for publication soon to add even more to this data set.This is the largest study of its kind, the most information EVER collected about what happens to the human body in space.So, what did we find?The researchers have identified, for the first time, a core set of mammalian adaptations in response to spaceflight.We see these changes across species: humans, mice and other animals.The biggest one?Mitochondrial dysfunction.You may think of the mitochondria as that famous ‘powerhouse of the cell’—it generates most of the energy a cell needs and so enables the proper function of all your tissues and organs.So, as you might imagine, keeping your mitochondria working is pretty important.Using new techniques that allowed a really in-depth look at changes in the astronauts’ genomes and protein expression,mitochondrial changes were consistent across the dataset.And even though the scientists are still unsure what EXACTLY may be the underlying cause of this mitochondrial disturbance,they think it’s likely oxidative stress caused by the extreme environment of space.This, essentially, is damage caused to cells by stress.Stress releases these harmful compounds called reactive oxygen species, causing genetic changesthat, in turn, cause changes in metabolic pathways.And honestly, the ‘changes’ they describe in this dataset are hilariously complicated.But the upshot of the whole mitochondrial discovery is that it gives us a way to put together a lot of the pieces.See, changes in mitochondrial function are likely the underlying cause of a lot of the other weird stuff we see in astronauts,like disrupted circadian rhythm, immune system dysfunction, and changes in organ activity.Because that was the other main discovery.Turns out, space is really hard on your liver!The liver undergoes more changes in gene and protein expression than any other organ while in space.And this is because your liver, with its role in blood filtration,is really important in sensing changes in blood composition and keeping your body as habitable as possible —or, to put it more scientifically, maintaining homeostasis.So, apparently, it has to work extra hard while in space.The dataset also confirmed that many astronauts’ telomeres lengthen while in space,but then shorten significantly when they come back to Earth — just like Scott Kelly’s did in the Twins study.The hypothesis for this is also...oxidative stress, problematic becausetelomeres are essential for preventing damage to your chromosomes.Not all of the changes were necessarily bad.Scott Kelly experienced a decrease in blood cell mutations during his year in space.Some astronauts exhibited increased levels of genetic tools that allowed them adapt slightlyto the effects of radiation and microgravity.And this 2020 dataset also confirmed that astronaut gut microbiomes take on a unique profile while in space(which I just think is super cool).Overall, all of this gives us a much more robust picture of what goes on in the body while in space,and what potential drugs or discoveries could make long-term spaceflight physiologically possible.And as the astronaut core is only getting more diverse, scientists want to conduct more studieswith even more human participants on even longer spaceflights to make our understanding of bodies in spaceas well-rounded as possible.Because work like this doesn’t just keep astronauts safe before and after their trips off-Earth —it gives us even more insight into human health here on the planet too.You can check out my previous video on the initial results of the NASA twin study here!Make sure you subscribe to Seeker for all of your spaceflight news,and if you have another topic you want us to cover in this area, let us know down in the comments below.As always, thanks so much for watching, and I’ll see ya next time.\n"