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Floating silently among the stars may seem idyllic, but the longer you stay in space, the more your immune system depends, according to these latest researches.
NASA has partnered with experts from the University of Arizona, the University of Houston and Louisiana State University, in the United States, to badyze blood samples of eight astronauts from the International Space Station. They discovered that natural killer cells (NK cells), a type of white blood cell essential for fighting viral infections and cancerous tumors, were damaged if they spent more than six months in space.
Blood samples were collected before, during and after the astronauts' stay in the scientific laboratory in orbit. Each batch of NK cells was stung against leukemia cells during a series of laboratory experiments, and the researchers watched the two groups fall apart.
They found that when the team members had spent 90 days in the space, the activity of their NK cells had decreased by about 50% and was less effective at combating the cancer cells.
Having a weak immune system in the space is dangerous, said Richard Simpson, badociate professor of nutrition science at the University of Arizona and lead author of the paper published by the American Physiology Society.
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"When you're at the space station, the environment is very sterile – you probably will not get the flu, a rhinovirus, or a community-type infection – but the problematic infections are the viruses that are already there. your body, "he explained earlier this month. These are mostly viruses that cause things like shingles, mononucleosis or cold sores; they stay in your body for the rest of your life and reactivate when you're stressed. "
Beyond viral infections, do not forget the onslaught of radiation particles from solar flares or intergalactic spaces, even with radiation protection in place. These highly energetic particles enter the human body and increase the risk of cancer and other degenerative diseases through genetic mutations. This is not the right time for the anticarcinogenic bio-policemen of your body to take a nap.
The effect will be even worse for future astronauts who embark on a long journey to Mars. Without the safe cocoon of the Earth's magnetic field, space explorers are exposed to higher radiation doses. Previous experience had revealed that a one – year round trip to the red planet absorbed more than half of the maximum recommended radiation dose for an astronaut 's entire career.
Interestingly, the effect of weakened NK cells was less pronounced in experienced astronauts than in novices. "Fortunately, we found that half of our crew members had already flown, and the other half had not done so," Simpson said. "The" recruits "have seen a greater decline in the function of NK cells compared to veterans."
The researchers do not know why the old players – one participant had spent 340 days in space – had a stronger immune system than the newcomers to space. This may be due to aging or the stress of adapting to a new unknown environment.
"When we look at the [NK cells] according to the samples of astronauts during the flight compared to their own samples before their flight, it breaks down. When we compare them to the controls that have remained on Earth, it continues to decline, "Simpson concluded. "I do not think there is any doubt about the fact that the function of NK cells decreases in the environment of spaceflights when it is badyzed in a cell culture system."
The mission on Mars could take up to three years. Astronauts hoping to see the red planet up close, will face a host of other health issues, such as back pain, long-term brain damage and distorted eyes. Thank you, space. ®
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