How Much Radiation Will Mars Explorers Have to Endure? Astrobiology Magazine

About eight months before the NASA rover Curiosity touches down on Mars in August 2012, the mission’s science measurements will begin much closer to Earth.
The Mars Science Laboratory mission’s Radiation Assessment Detector, or RAD, will monitor naturally occurring radiation that can be unhealthful if absorbed by living organisms. It will do so on the surface of Mars, where there has never before been such an instrument, as well as during the trip between Mars and Earth.
RAD’s measurements on Mars will help fulfill the mission’s key goals of assessing whether Curiosity’s landing region on Mars has had conditions favorable for life and for preserving evidence about life. This instrument also will do an additional job. Unlike any of the nine others in this robotic mission’s science payload, RAD has a special task and funding from the part of NASA that is planning human exploration beyond Earth orbit. It will aid design of human missions by reducing uncertainty about how much shielding from radiation future astronauts will need. The measurements between Earth and Mars, as well as the measurements on Mars, will serve that purpose.