Many people have asked me what the dangerous radiation levels are. The answer that I’ve found is 100,000uSv in a year. Cancer has been directly linked to this exposure value. Jet pilots and Flight Attendants can expect to get around 6000uSv per year if they fly 800 hours. That’s not to say radiation can’t make you sick at lower levels. It can. But it’s really hard to link things like the common cold to a couple days of flying at high altitude. This is what has caused so much confusion about it and why it’s so hard to find concrete data on what radiation can do. The best advice I can give to aircrew and frequent flyers is to maintain a healthy lifestyle. Any detrimental affects to the mild doses we receive are probably magnified by poor eating and other health habits.
So what’s the radiation level at the International Space Station?
I’ve been getting measurements at a maximum altitude of 8.5 miles. The International Space Station orbits at about 280 miles up. The average astronaut on the ISS, during their 6 month stay, gets a whopping 70,000 uSv! So you can see why they don’t, normally do more than 6 months.
In fact, man will never conquer space travel without handling the radiation problem. Low Earth Orbit is about the best we can do for extended periods of time, right now. The Van Allen belts extend from roughly 600 miles to 22,000 miles above the Earth. These are belts of high levels of radiation that men can’t stay in for long. Above this, the effects of the Earth’s magnetosphere are so diminished, that solar activity is uninhibited.
Throughout the years of the Apollo moon landings, there were regular solar flares. A couple of them would have cooked the astronauts going to the moon. The success of these missions was mostly luck of timing. The future of space travel depends entirely on finding the best ways to shield against radiation.