Sunlight Can Kill You!

We all know the Sun produces U.V. rays and that if you spend too much time sunbathing, you’ll probably get skin cancer. Well, the Sun spews a lot of other stuff into space too. Ultraviolet radiation may be the least of your worries if you happen to live in space.

In addition to U.V. rays, the Sun also produces:

  • X-rays: sort of like U.V. rays, only with more energy and, therefore, more harmful.
  • Gamma rays: even more energetic and harmful than X-rays.
  • Solar ejecta: solar flares and other nasty explosions on the Sun can accelerate protons, electrons, and other little bits and pieces of atoms to ludicrous speeds. Do not stand in their way!

Fortunately, Earth’s atmosphere and magnetic field protect us from most of the Sun’s deadly radiation. Even the crew of the International Space Station are in a low enough orbit that Earth still keeps them safe. Well, safe-ish.

But all this radiation makes human space exploration beyond low Earth orbit extremely hazardous. Before sending astronauts to the Moon, NASA had to wrestle with their collective conscience over how much radiation exposure should be considered acceptable. Now, NASA is wrestling with its conscience again as it plans to send astronauts to Mars.

Current technology cannot protect humans from solar radiation. The problem gets worse with increased solar flare activity. One of the things science fiction writers (like myself) have to figure out is how to keep our characters from dying of radiation sickness within the first few chapters of our books.

P.S.: Starlight can kill you too. In addition to solar radiation, astronauts have to worry about cosmic radiation: radiation from other stars, quasars, and God knows what else.

9 thoughts on “Sunlight Can Kill You!

  1. Amazingly – some women wanting to go to Mars are complaining of discrimination – because the “acceptable” radiation levels for female astronauts are lower than for male ones!. That’s because – biological fact – women are more susceptible to radiation than men are. It’s as if they don’t care if they put themselves in more danger.


    1. I think the bigger issue is that NASA sets its radiation safety guidelines on a rather arbitrary basis depending on their current mission. Radiation exposure for a Mars mission is so high that (it pains me to say this) we probably shouldn’t allow anyone to go, regardless of gender.

      But since we are going, setting an arbitrary safety guideline that just so happens to exclude women does seem a bit sexist. I’m willing to give NASA the benefit of the doubt that they’re trying to do the right thing, but I can understand why women astronauts might think the current policy is unfair.


  2. It’s my understanding that the NASA red line for solar radiation exposure is a conservative estimate based on pretty much no data. They just picked one. This may contribute to the dissatisfaction of being excluded. Other astronauts, including men, have been grounded because they were approaching the “line” of acceptable radiation exposure, and they don’t take it well. In absence of any usable data, NASA feels it must be ultra conservative to protect its astronauts. And the type of person who’s willing to rocket into space is ready to take risks, so yeah, female astronauts are mentally more inclined to accept risks in order to further science.


  3. That makes sense. As I said, I’m sure NASA is trying to do the right thing. We probably won’t know all the risks associated with space travel until we’ve done a lot more of it. Until then, the debate over what is or is not safe will continue.


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