space travel kills you
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Researchers Discover Yet Another Way That Space Travel Kills You

New research shows that space travel slowly kills you due to the effects of zero gravity on the immune system. Engineers that plan future human space missions already mitigate a range of known hazards from traveling in space, including things like radiation and bone loss, so this latest research only adds to the growing list of things that make space travel particularly dangerous to humans.

Longer and More Complex Space Missions Reveal More Ways Space Travel Kills You

As humanity travels deeper and deeper into space, including upcoming missions to the moon and Mars, technological advancements will be needed to keep these astronauts safe and healthy. Some of the worst effects of radiation in space have been somewhat mitigated by shielding during flight, but fears of long-term exposure may force would-be space colonists to live underground.

Gravity is another issue. More specifically, the lack of gravity experienced by humans in space has proven to be particularly challenging. Some exercise and resistance training have helped, but over time, astronauts tend to lose significant bone and muscle mass. There are also deleterious effects on human eyes, hearts, and other organs from long-term exposure to zero-g environments.

Now, a research team says that a weakening immune system may also result from time on zero-g, with the worst effects resulting in a decreased resistance to infection, latent viruses, and even cancer.

Simulated Zero G Causes T-Cells to Become Less Effective

To evaluate the effects of zero-g on T-cells, a key component of the human immune system when it comes to fighting infections and tumor growth, Lisa Westerberg, principal researcher at the Department of Microbiology, Tumor and Cell Biology, Karolinska Institute, and team recruited volunteers to undergo a simulated zero gravity experiment. Called “dry immersion,” the technique involves having volunteers spend long periods of time each day in a type of water bed that has been custom-built to “trick” the body into thinking it is in a zero-g environment.

For their experiment, Westerberg and the research team exposed volunteers to this simulated zero-g for a total of three weeks. Blood analyses were performed before the study began and then again after 7, 14, and 21 days of simulated zero-g exposure.

Those tests revealed that the zero-g environment seemed to change the way genes were expressed by the T-cells, resulting in a less effective infection and tumor fighter.

“The T cells began to resemble more so-called naïve T cells, which have not yet encountered any intruders,” explained Carlos Gallardo Dodd, Ph.D. student at the Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet. “This could mean that they take longer to be activated and thus become less effective at fighting tumour cells and infections.”

In effect, the result of the zero-g exposure revealed yet another way that space travel kills you.

Preparing the Human Immune System for Long-Term Zero G Exposure

Published in the journal Science Advances, the new study seems to indicate that exposure to zero-g weakens T-cells by making them less effective. Fortunately, learning this now offers researchers the opportunity to look for treatments and mitigation strategies before astronauts start dropping dead from the common cold.

“If astronauts are to be able to undergo safe space missions, we need to understand how their immune systems are affected and try to find ways to counter harmful changes to it,” said Westerberg. “We’ve now been able to investigate what happens to T cells, which are a key component of the immune system when exposed to weightless conditions.”

Dodd agrees, noting that “Our results can pave the way for new treatments that reverse these changes to the immune cells’ genetic programme.”

Christopher Plain is a Science Fiction and Fantasy novelist and Head Science Writer at The Debrief. Follow and connect with him on X, learn about his books at, or email him directly at