NASA Advisory Council Recommendation 

Radiation Risk for Human Mars Missions 

2015-02-03 (SC/HEOC-01) 

Recommendation: 

The Council recommends that NASA openly communicate the radiation risks while proceeding 

with preparations to send hwnans to Mars in the 2030s. As part of the mission development 

process, NASA should continue its work to mitigate radiation risks through improved knowledge 

and technology. In particular, there may be additional means of investigating the full extent of the 

radiation problem (for example, stellar observations, geologic record, further understanding of the 

heliospheric environment). Synthesizing expertise from both human exploration and science is 

essential to achieving this goal. Furthermore, we encourage NASA to initiate a long-term medical 

care program for astronauts which includes long-term astronaut health monitoring to mitigate long 

duration exposure health consequences, and build a baseline for future long-term health and 

engineering decisions. 

Major Reasons for Proposing the Recommendation: 

The Council's Science Committee and Human Exploration and Operations Committee were 

impressed by the breadth and depth of the radiation research presentations and progress being made 

for understanding the nature of the deep space radiation environment, its implications for human 

space flight and the ethical issues that arise. The overarching message was that radiation for deep 

space flight is indeed a serious issue to be addressed as technology and understanding evolve. It 

was also clear that it is not likely we can mitigate all radiation risks to fully meet current radiation 

health standards. Therefore, some level of risk must be accepted (mission risk and long-term 

astronaut health risk) within the broader context of all risks associated with a mission to Mars. 

Because knowledge of key components continues to move forward, it is difficult to quantify the 

overall risk. For example, it is not clear how accurately we can defme mission risk and long-term 

astronaut health risk based on our current understanding ofheliophysics and human biology. Still, 

based on current estimates of the radiation risk, sending hwnans to Mars seems to be reasonable at 

this time. 

Consequences of No Action on the Proposed Recommendation: 

Accurate information regarding the Agency's planned approach to the critically important issue of 

radiation safety will not be adequately provided to all the relevant stakeholders. 

NASA Response: 

NASA concurs with the recommendation of the NASA Advisory Council. Work to mitigate 

radiation risks will continue through the research and technology development efforts of the Hwnan 

Exploration and Operations, Science, and Space Technology Mission Directorates. Overall mission 

risks, including those posed by radiation, will be assessed and communicated through appropriate 

processes and mechanisms. Finally, while NASA concurs with the concept of "a long-term medical 

care program for astronauts .... " as stated in the recommendation, it should be recognized that 

NASA's ability to provide such a program is limited by the authority given to the Agency by 

statute. 

Enclosure