July 18, 2024
1 Solar System Way, Planet Earth, USA

Short trips into space can take a toll on an astronaut's body

Only about 600 people have ever traveled to space. The vast majority of astronauts For the past six decades, they have been middle-aged men on short-duration missions of less than 20 days.

Today, with the entry of private, commercial and multinational space flight providers and pilots into the market, we are witnessing a new era of manned space flight. Missions have lasted from minutes, hours and days to months.

As humanity looks to the future, Returning to the Moon In the next decade, space exploration missions will be much longer and there will be many more space travelers and even space tourists. This also means that a greater diversity of people will experience the extreme environment of space: more women and people of different ethnicities, ages and health statuses.

Because people react differently to the particular stressors and exposures of space, space health researchers like myself seek to better understand the effects of spaceflight on human health. With that information, we can determine how to help astronauts stay healthy both while in space and once they return to Earth.

As part of the NASA's landmark twin studyIn 2019, my colleagues and I published groundbreaking research on how a year aboard the International Space Station affects the human body.

I am a Biologist specializing in radiotherapy cancer in the Department of Environmental and Radiological Health Sciences at Colorado State University. I have spent the last several years building on that earlier research in a series of recently published papers. published across the Nature portfolio of journals.

These documents are part of the Medical and Spatial Omics Atlas Manuscript Packagedata, protocols and repositories representing the largest collection ever assembled on aerospace medicine and space biology. More than 100 institutions from 25 countries contributed to the coordinated publication of a wide range of spaceflight data.

NASA's twins study

Retired NASA twin astronauts Scott and Mark Kelly. Credit: NASA

From NASA Twin study He took advantage of a unique research opportunity.

NASA selected astronaut Scott Kelly for the agency's first one-year mission, during which he spent a year aboard the International Space Station between 2015 and 2016. During the same period, his identical twin brother, Mark Kelly, a former astronaut and current U.S. senator representing Arizona, remained on Earth.

My team and I examined blood samples We collected data from the twin in space and his genetically matched twin on Earth before, during, and after spaceflight. We found that Scott's telomeres… Protective caps at the ends of chromosomes, much like the plastic tip that keeps a shoelace from fraying, lengthened, quite unexpectedly, during its year in space.

However, when Scott returned to Earth, his telomeres shortened rapidly. Over the next few months, his telomeres recovered, but they were still shorter after his trip than they were before he went into space.

As we age, telomeres shorten due to various factors, including stress. Telomere length can serve as a biological indicator their risk of developing age-related diseases such as dementia, cardiovascular disease and cancer.

In a separate studyMy team studied a cohort of 10 astronauts on six-month missions aboard the International Space Station. We also had a control group of age- and sex-matched participants who remained on the ground.

We measured telomere length before, during and after spaceflight and again found that telomeres were longer during spaceflight and then shortened upon return to Earth. Overall, astronauts had significantly shorter telomeres after spaceflight than before.

One of the other researchers in the Twins Study, Christopher Masonme too conducted another study of telomeres – this time with twin mountain climbers, a fairly similar extreme environment on Earth.

We found that while climbing Mount Everest, the climbers' telomeres were longer, and after descending, they became shorter. Their twins who remained at low altitude did not experience the same changes in telomere length. These results indicate that it is not the microgravity of the space station that caused the changes in telomere length that we observed in the astronauts, but other culprits, such as increased exposure to radiationIt is more likely.

Civilians in space

SpaceX's Inspiration4 crew. Each crew member is a civilian who flew into orbit on a SpaceX Dragon spacecraft. Credit: SpaceX

In our latest studyWe studied telomeres of the crew aboard SpaceX’s 2021 Inspiration4 mission. This mission featured the first all-civilian crew, whose ages spanned four decades. Telomeres of all crew members lengthened during the mission, and three of the four astronauts also showed telomere shortening once they returned to Earth.

What's particularly interesting about these findings is that the Inspiration4 mission lasted only three days. So not only do scientists now have consistent and reproducible data on the telomere response to spaceflight, but we also know that it happens quickly. These results suggest that even short trips, such as a weekend getaway to space, will be associated with changes in telomere length.

Scientists do not yet fully understand the impact that these changes in telomere length have on health. We will need more research to determine how long and short telomeres may affect an astronaut's long-term health.

Telomeric RNA

In another articleWe showed that the Inspiration4 crew, as well as Scott Kelly and high-altitude mountain climbers, exhibited increased levels of telomeric RNA, termed TERRA.

Telomeres are made up of numerous repetitive DNA sequences, which are transcribed into TERRA, which contributes to the structure of telomeres and helps them perform their function.

Together with laboratory studies, these findings tell us that telomeres are being damaged during spaceflight. While there is still much we don't know, we do know that telomeres are especially sensitive to oxidative stress. Therefore, the chronic oxidative damage experienced by astronauts when exposed to space radiation 24 hours a day likely contributes to the telomere responses we observe.

We also wrote a Review article with a more futuristic perspective. A better understanding of telomeres and aging could help determine the ability of humans not only to survive long-duration space travel, but also to thrive and even colonize other planets. To do so, humans would have to reproduce in space, and future generations would have to grow up in space. We don't know if that's possible — yet.

Plant telomeres in space

My colleagues and I also contributed other work to the Spatial Medical and Omics Atlas package, including: An article published in Nature CommunicationsThe study team, led by Texas A&M biologist Dorothy Shippen and biologist at Ohio State University Sarah WyattThey found that, unlike people, plants that flew in space did not have longer telomeres during their stay aboard the International Space Station.

However, the plants increased their production. telomerase productionthe enzyme that helps maintain telomere length.

As anyone who has seen “The Martian”You know, plants will play an essential role in long-term human survival in space. This finding suggests that plants may be better adapted by nature to withstand the stressors of space than humans.

This article is republished from The conversation under Creative Commons license. Read the original article.

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