Radiation Measurements of the Mars Science Lab Radiation Assessment Detector (MSL-RAD) on the Surface of Mars

Abstract

The Radiation Assessment Detector (RAD) was designed to characterize the radiation environment as “Life Limiting Factor” to habitability and to help to prepare for future human exploration of Mars. The Mars Science Laboratory spacecraft (MSL), containing the Curiosity rover, in which RAD is integrated, was launched to Mars on November 26, 2011. Although not part of the mission planning, RAD was operated already during the 253 day and 560 million km cruise to Mars and made the first detailed and time-resolved measurements of a radiation environment that will exist inside future spacecraft carrying humans to Mars and in other deep space missions. On August 6, 2012 the Curiosity rover landed on the surface of Mars. RAD started measuring the surface radiation exactly 100 years after the discovery of cosmic rays on August 7, 1912 RAD made the first observation of the radiation environment on the surface of another planet and is still gathering/recording data today. Here we present data on particle fluxes, absorbed dose and dose equivalent from both galactic cosmic rays and solar particles together with model calculations. The dose equivalent rate is found to be 0.64±0.12 mSv/day on the surface on Mars from Aug 7, 2012 until June 1, 2013 and 1.84±0.3 mSv/day during cruise. The high level of complexity of the data allows for benchmarking of space radiation transport models and thereby supports the validation and improvement of predictive models for health risks of astronauts during space missions.