  Space radiation is a major risk for humans, especially on long-duration
missions to outer space, e.g., a manned mission to Mars. Galactic cosmic rays
(GCR) contribute a predictable radiation background, the main risk is due to
the highly variable and currently unpredictable flux of solar energetic
particles (SEPs). Such sporadic SEP events may induce acute health effects and
are thus considered a critical mission risk for future human exploration of
Mars. Therefore, it is of utmost importance to study, model, and predict the
surface radiation environment during such events. It is well known that the
deep-space SEP differential energy spectrum at high energies is often given by
a power law. We use a measurement-validated particle transport code to show
that, for large SEP events with proton energy extending above ~ 500 MeV with a
power-law distribution, it is sufficient to measure the SEP flux at a pivot
energy of ~ 300 MeV above the Martian atmosphere to predict the dose rate on
the Martian surface. In conjunction with a validation by in-situ measurements
from the Martian surface, this remarkable simplification and elegant
quantification could enable instant predictions of the radiation environment on
the surface of Mars upon the onset of large SEP events.
