Traveling to space is a shock to the human body. Despite our surprising adaptability, every system in the body is changed by being in microgravity. Bones lose calcium, muscles lose mass, and body fluids shift towards the head.
Another risk to space travelers is the increase in cosmic radiation. Here on Earth, we are shielded by the magnetic field of our planet. Beyond the magnetosphere, the increase in cosmic rays is such that before going to sleep, astronauts sometimes see flashes of light due to these particles hitting the retina.
Obviously, a rise in radiation can also lead to an increased rate of cancer. Therefore, scientists were curious to find out whether people who have been to space do indeed experience higher rates of the disease. As published in Scientific Reports, an American-Russian team of researchers looked at historical data on 301 astronauts and 117 cosmonauts that have been to space since 1959.
A potential connection between space and increased risk of cancer has long been investigated, but previous analyses couldn’t find any strong evidence one way or the other. This work reanalyzes all of that historical data and concludes that going to space doesn’t lead to an increase in cardiovascular disease or death from cancer.
“Based on the results reported here, we again fail to find evidence sufficient to conclude that historical doses of space radiation pose an excess mortality risk for astronauts and cosmonauts,” the researchers write in their paper.
While this is exciting news, it is also important to remember that space travel has changed significantly over the last 30 years. We have moved from short orbital flights to circum-lunar forays, to longer and longer missions in low-Earth orbit.
“[I]t is important to note that future missions of deep space exploration will likely offer much greater doses of space radiation than have historical doses, which will lead to a different risk profile for future astronauts and cosmonauts,” the team writes.
The Artemis program, which wishes to see NASA put humans back on the Moon by 2028, will have a permanent settlement on the surface and an orbital station around our natural satellite with individual missions lasting months. A mission to Mars, which is the next step in the program, will take years.
It is crucial that these types of studies are continuously updated, and their data analyzed and reanalyzed with both novel and current approaches.