Astronauts and cosmonauts aren’t at any elevated risk from radiation damage — at least so far. (Credit: NASA)

As NASA and other agencies look forward to placing humans on the Moon, Mars, and other destinations far beyond Earth’s sheltering atmosphere and magnetic fields, their worries about the harmful radiation that permeates space will only grow.

Many aspects of how the human body will react to long periods in space remain unknown. But using the small group of people who have already b