Radiation risks
Here on terra firma, we’re protected from cosmic radiation by Earth’s magnetic shield, which includes the
Van Allen belts. Outside this zone, however, highly charged particles streaming from the Sun (or beyond) can
slice through the bodies of astronauts, damaging cells.
This causes a whole host of issues, such as radiation sickness and increased lifetime risk of cancer. Right now, we mitigate the risk of radiation by shielding spacecraft and closely monitoring radiation exposure.
But research also suggests that cosmic radiation during a Mars trip might cause more immediate issues. Radiation damage to tissue may affect astronauts’ behavior, cognition, and general health while on the Moon or Mars, so it’s vital to shield a lunar or martian crew from as much of it as possible.
Some potential solutions including building habitats with an insulating layer of water, which effectively blocks radiation. Or by shielding habitats with a layer of readily available regolith. Or, perhaps, the answer is to tweak our own genomes.
Professor Nesrin Sarigul-Klijn, a specialist in aerospace engineering, believes that the best way to protect astronauts from radiation is a multi-pronged approach. “The most exciting countermeasures, in our eyes, are the ones that seek to unite hybrid approaches to radiation mitigation.”
Though the exact countermeasures that will be used during a Moon or Mars journey are still up for debate, Sarigul-Klign argues that combining both spacecraft shielding and biological methods, such as gene editing, will provide the most protection from hazardous space radiation
Hazards to the microbiome
Many aspects of our health, from good digestion, to stable mood, to healthy skin, are maintained by our microbiome — the complex cultures of bacteria, fungi, protozoa, and viruses that live on and inside us.
In space, however, the balance of these tiny helpers changes from what you’d expect on Earth. Studies following astronauts who have recently stayed on the ISS show that microbial diversity in the gut increases upon return to Earth, whereas in other areas of the body, such as the nose, it decreases. These microbiome changes may relate to common astronaut health issues, such as skin rashes and episodes of hypersensitivity.
While researchers are getting a grip on these changes in low-Earth orbit, some experts believe that we’re likely to run into different alterations of the microbiome during extended trips to other worlds.
“Cosmic radiation, for instance, may increase the mutation rate of commensal bacteria,” explains Hernan Lorenzi, an expert on the astronaut microbiome and profess at the J. Craig Venter Institute. These bacteria help instigate protective immune responses in the human body. So, if they mutate more often, it “may potentially lead to new bacterial behaviors and the way they interact with the human host,” adds Lorenzi.
But some of the best solutions for keeping spacefarers’ microbiomes healthy seem deceptively simple.
“Maintaining a healthy, balanced diet will be very important,” says Lorenzi. “Diet could be complemented with the use of prebiotics and probiotics.”But he also notes significant challenges, such as an astronaut needing antibiotics. Treating an astronaut with antibiotics can deplete the natural supply of probiotics in their microbiome.
However, according to a paper co-authored by Lorenzi, the answer to that problem might be fecal transplants:
“One option for emergency in-flight antibiotic use may be to package astronauts' stool into probiotic capsules while they are healthy on Earth. This would allow an astronaut to refresh their GI microbiome with a diverse set of organisms from their own healthy GI tract. Regardless of the source, one or more methods of rebalancing a damaged microbiome will be essential for long-duration space missions.”