  Current radiobiology studies on the effects of galactic cosmic ray radiation
utilize mono-energetic beams, where the projected dose for an exploration
mission is given using highly-acute exposures. This methodology does not
replicate the multi-ion species and energies found in the space radiation
environment, nor does it reflect the low dose-rate found in interplanetary
space. In radiation biology studies as well as in the assessment of health risk
to astronaut crews, the differences in the biological effectiveness of
different ions is primarily attributed to differences in the linear energy
transfer (LET) of the radiation spectrum. Here we show that the LET spectrum of
the intravehicular environment of spaceflight vehicles can be simulated with a
single particle, mono-energetic ion beam accelerated at target blocks
constructed of one or more materials. The LET spectrum of the emerging field
can then be moderated by the amount of mass or length of material the primary
and secondary nuclei travels, thus preferentially producing specific nuclear
spallation and fragmentation processes and allowing for a continuous generation
of ionizing radiation that mimics the space radiation environment. This
approach could allow more accurate simulation of not only intravehicular
spaceflight conditions, but also could be used to simulate the external
galactic cosmic ray field, planetary surface spectrum (e.g., Mars or Moon), and
the local radiation environment of orbiting satellites, providing a much-needed
ground-based space radiation analog for future experimentation.
