  One of the major issues to be solved is the protection from the effects of
ionizing radiation. Exploration mission, lasting two to three years in space,
represents a very significant step from the point of view of radiation
protection: both the duration (up to 5 times) and the intensity (up to 5 times)
of the exposure to radiation are increased at the same time with respect to
mission on the ISS reaching and sometime exceeding professional career limits.
In this ARSSEM report, after reviewing the physics basis of the issue of
radiation protection in space, we present results based for the first time on
full physics simulation to understand the interplay among the the various
factors determining the dose absorbed by the astronauts during a long duration
mission: radiation composition and energy spectrum, 3D particle propagation
through the magnetic field, secondary production on the spacecraft structural
materia, dose sensitivity of the various parts of the human body. As first
application of this approach, we use this analysis to study a new magnetic
configuration based on Double Helix coil and exhibiting a number of interesting
features which are suited to active shield application. The study also proposes
a technology R&D roadmap for active radiation shield development which would
match ESA decadal development strategy for human exploration of space.
