Rien de tel que la merde pour se protéger des radiations solaires.
A 17-month-long dose of space radiation would be seriously bad news. The good news, though, is that water and organic materials can both be effective shields against radiation exposure, and any manned space voyage will necessarily involve plenty of both. MacCallum said the Inspiration Mars spacecraft could leave Earth with its walls lined with bags of drinking water and food. Then, as the astronauts consume these provisions over time, the empty bags could be replaced with others that the craft's occupants had filled with solid and liquid human waste.
[The Register : Tito's Mars mission to use human waste as radiation shield. ]