Scientists Prove That Human Gut Bacteria Can Survive a Trip to Space Without Us

Space travel is not for the weak. Astronauts suffer from motion sickness, disorientation, and cardiovascular stress before they reach orbit. Fortunately, the bacteria that live inside us are much more resilient. Gut bacteria essential to human health can withstand the stress of being launched into space on a rocket, the microgravity environment, and reentering Earth’s atmosphere, a new study shows.

A group of scientists in Australia launched spores of Bacillus subtilis, a Gram-positive bacteria that lives in our gut, to the edge of space to see how well the microbes fare. Upon examination after the bacteria returned to Earth, scientists found that the microbes had not seen any change in their ability to grow and that their structure remained intact.

The findings were detailed in a study published Monday in the journal npj Microgravity. The work suggests that bacteria are likely functioning as needed inside the gut of any human en route to Mars, information that is important for astronauts’ health. But it also suggests that contamination of Mars with terrestrial bacteria may be inevitable.

Space-faring bacteria

Previous experiments aboard the International Space Station (ISS) have shown that certain types of bacteria can survive in space. However, not much research has been done on the effects of rocket launch and reentry on human gut bacteria survival rates.

In order to test the bacteria, the researchers packed the spores aboard a sounding rocket and launched it about 160 miles (260 kilometers) above the Earth’s surface. During the second stage of burn, the rocket experienced a maximum acceleration of 13 Gs (or 13 times the force of gravity).

Once it reached the desired altitude, the researchers initiated a short period of weightlessness that lasted for about six minutes when the main engine stopped. The rocket then began descending to Earth, slowing down with a force of 30 Gs while rotating at a rate of 220 times per second.

After the arduous journey, the researchers examined the bacteria’s spores to see how well they survived during the rocket’s launch and re-entry into the atmosphere. Surprisingly, the bacteria did not show any change in their structure, nor did the intense forces affect their ability to grow.

“Our research has shown that a species of bacteria important for our health can withstand rapid changes in gravity, acceleration, and deceleration,” Elena Ivanova, a professor at the Royal Melbourne Institute of Technology in Australia, and a co-author of the study, said in a statement. “It has expanded our understanding of the effects of long-duration spaceflight on the microorganisms that live in our bodies and keep us healthy. This means we can design better life support systems for astronauts to keep them healthy during long missions.”

However, the idea of ​​bacteria surviving and thriving on their way to the Red Planet isn’t always met with enthusiasm. These findings follow a separate study published last year that warned that bacteria not only have the ability to survive a trip to Mars, but also feel at home in Martian soil. As space agencies plan human missions to Mars, there is growing concern that these missions could contaminate the Martian environment without Earth’s microbes. This could lead to false detections of life on the planet, but it could also pose a direct danger to the astronauts themselves – or, indeed, to any life that might exist on Mars in the first place.