  The composition of the space radiation environment inside spacecrafts is
modified by the interaction with shielding material, with equipment and even
with the astronauts' bodies. Accurate quantitative estimates of the effects of
nuclear reactions are necessary, for example, for dose estimation and
prediction of single-event-upset rates. To this end, it is necessary to
construct predictive models for nuclear reactions, which usually consist of an
intranuclear-cascade or quantum-molecular-dynamics stage, followed by a
nuclear-de-excitation stage.
  While it is generally acknowledged that it is necessary to accurately
simulate the first reaction stage, transport-code users often neglect or
underestimate the importance of the choice of the de-excitation code. The
purpose of this work is to prove that the de-excitation model is in fact a
non-negligible source of uncertainty for the prediction of several observables
of crucial importance for space applications. For some particular observables,
the systematic uncertainty due to the de-excitation model actually dominates
the total uncertainty. Our point will be illustrated by making use of
nucleon-nucleus calculations performed with several
intranuclear-cascade/de-excitation models, such as the Li\`{e}ge Intranuclear
Cascade model (INCL) and Isabel (for the cascade part) and ABLA07, Dresner,
GEM, GEMINI++ and SMM (on the de-excitation side).
