Elon Musk was asked about this after his Mars announcement and he didn't seem to think it was a big issue. Not saying he's right, but he's not dumb either.
I'd say Musk has been a fanatic about sending men to Mars since he was a child. Today, he's a grownup child with billions of dollars to spend on his dreams and his toys. And a still a fanatic. Not dumb, but not reasonable either. It's not possible for a fanatic to be reasonable.
http://www.smithsonianmag.com/scien...ns-problem-any-mission-mars-180959092/?no-ist
In the vast emptiness of space, two forms of radiation menace astronauts: Cosmic rays zip through the galaxy at near-light speeds, while solar activity produces a more subdued form of radiation. Both are a problem for space travelers, causing conditions ranging from impaired vision to cancer.
This radiation isn’t a problem here on Earth thanks to the planet's protective atmosphere, which blocks the worst of it. But engineers still don’t have effective methods to shield astronauts from these dangers, and that adds an extra level of risk to already risky plans to send
humans to Mars on a
three-year journey by the 2030s.
"There may be mission-level risks that literally put the mission at risk—the whole mission, not just the individual astronauts—if one or more crew members are incapacitated," says radiation expert Ron Turner, a senior science adviser at NASA's Institute for Advanced Concepts in Atlanta who studies risk management strategies for human space missions. "It's important that we get that data over the next ten years so we are able to make prudent planning for a future Mars mission."
The sun constantly sheds energetic particles through the solar wind. And levels of these particles rise and fall during the sun’s 22-year solar cycle. Solar storms also can hurl massive blobs of charged particles into space, with the 11-year peak producing the most activity. The powerful radiation can not only increase long-term cancer risks but also cause immediate issues such as
vomiting, fatigue and vision problems.
http://www.space.com/24731-mars-radiation-curiosity-rover.html
The
Mars rover Curiosity has allowed us to finally calculate an average dose over the 180-day journey. It is approximately 300 mSv, the equivalent of 24 CAT scans. In just getting to Mars, an explorer would be exposed to more than 15 times an annual radiation limit for a worker in a nuclear power plant.
Data from Curiosity also demonstrated that landing only partially solves the problem. Once on the Martian surface, cosmic radiation coming from the far side of the planet is blocked. This cuts down detected GCRs by half. The protection from strong solar particles, though, is shoddy and inconsistent. Substantial variations in SEPs occur as the meager Martian atmosphere is tussled by solar wind.
"The variability [in radiation levels] was much larger than expected," Hassler said. "[This creates] variability in weekly and monthly dose rates. There are also seasonal variations in radiation."
