The recent Mars photos make it seem like humans are closer than ever to landing on Mars. One of the biggest unknowns in space travel is exactly what effect radiation from the Sun and cosmic rays will have on the human body for the 1,000 days a journey to Mars might take. Deep space is filled with protons from solar flares, gamma rays from newborn black holes, and cosmic rays from exploding stars. A long voyage to Mars, with no big planet nearby to block or deflect that radiation, is going to be a new adventure. NASA weighs radiation danger in units of cancer risk. A healthy 40-year-old non-smoking American male stands a (whopping) 20 percent chance of eventually dying from cancer if he stays on Earth. If he travels to Mars, the risk goes up. The question is, how much?
Universe Today February 19, 2004