It's "the elephant in the room," NASA Chief Astronaut Robert Behnken recently told a National Academy of Sciences committee.
"We're talking about a lot of ionizing radiation, almost a guarantee for cancer, and you are really close to the edge of the range for lethal exposure," said Kristin Shrader-Frechette, a University of Notre Dame professor and a specialist in ethical issues that arise in scientific research and technology development. "If we can't get shorter transit times in space, and we can't get better shielding, then we really can't do (a Mars) spaceflight."
The situation is prompting a wholesale reconsideration of how much space radiation astronauts can be exposed to and whether those limits should be eased to enable deep-space exploration. .
The prospect raises scores of thorny questions, including these:
• Should astronauts be allowed to volunteer for a flight when NASA knows space radiation exposure limits almost surely will be exceeded?
• Should a true understanding of the risk, and informed consent, be enough for someone to volunteer for a Mars mission?
• Should NASA's chief astronaut or chief medical officer be given authority to grant individual waivers to the limits?
• Should NASA, Congress or the White House have the authority to knowingly approve a waiver, or going even further, a one-way mission to the red planet — one that includes no plans for a return to Earth?
The jury is still out. The National Academy's Institute of Medicine took up the issue this year and is deliberating. A report is due in April 2014.
The Bible has this to say on the topic...
The heaven, even the heavens, are the LORD'S: but the earth hath he given to the children of men.