Boldly going to the final frontier may be the stuff of Star Trek dreams, but it can be dangerous — and not only in the sense of a possible asteroid collision.
Cosmic radiation can be a literal killer for astronauts blasting off into deep space. If this still sounds like sci-fi horror, researchers at Georgetown University Medical Center recently published a study in the Proceedings of the National Academy of Sciences (PNAS) that reveals how exposure to galactic cosmic radiation (GCR) could do severe enough gastrointestinal damage to spawn stomach and colon tumors.
Once you break free from Earth’s atmosphere, you are subjected to forces that could mutate your cells and permanently alter your DNA. Heavy ions (radiation made up of particles heavier than helium) are something Earthlings on terra firma don’t have to worry about because our planet’s magnetosphere protects against them. The research team had previously found that heavy ions have the power to damage to brain tissue and even fast-forward aging.
“Proliferative gastrointestinal (GI) tissue is radiation-sensitive, and heavy-ion space radiation with its high-linear energy transfer (high-LET) and higher damaging potential than low-LET gamma rays is predicted to compromise astronauts’ GI function,” senior investigator and NASA Specialized Center of Research (NSCOR) GUMC project leader Kamal Datta and his team write.
Even X-rays and gamma rays, which are massless photons shooting through space, are nowhere near as potentially harmful as heavy ions like iron and silicon that are much higher in mass. Shielding technology is leveling up, but no superhero space suits that would be able to block heavy ions and other potentially cancerous forms of radiation have appeared yet, and neither have any medicines that could possibly give the human body immunity. While astronauts on a moon mission are probably not at risk for irreversible damage, the future odyssey to Mars could mean peril.
Datta’s team exposed mice to iron radiation to study its effects on the small intestine. Cells in the human GI tract are constantly supposed to renew themselves, with the mucosal layer on top regenerating every several days. Anything that messes with that could result in malfunctions and mutations that ultimately lead to cancer. Mice exposed to heavy ions over a period of time supposed to mirror a trip into deep space were much worse off than those exposed to gamma rays, with warped DNA and an increase in senescent cells, which make voyaging far beyond Earth even more of a risk.
"They generate oxidative stress and inflammatory molecules that induce more damage. This greatly affected migration of cells that are needed to replace the intestinal lining which slowed down GI functioning," Datta told Phys.org of the damage that could be inflicted by senescent cells.
Does this mean a human mission Mars is an impossibility in our lifetime? Not necessarily, but however thrilling it would be to witness those first boot prints in the red dust making the evening news, what is more important is that the astronauts themselves live to tell about it.