Downplaying Radiation Is Dangerous
Musk has often said that radiation is not a major threat. But scientists disagree. Space is full of cosmic rays and solar particles. Unlike Earth, Mars has no strong magnetic field or thick atmosphere to offer protection.
During the six to nine month trip to Mars, astronauts would face high doses of radiation that could increase cancer risk, harm the brain, and damage internal organs. Once on the surface, the danger does not go away. The best known protection involves surrounding habitats with thick materials like water or rock. For example, twenty centimeters of water could reduce exposure. But that kind of shielding would be heavy and expensive to launch.
