  Precision mass spectrometry of neutron-rich nuclei is of great relevance for
astrophysics. Masses of exotic nuclides impose constraints on models for the
nuclear interaction and thus affect the description of the equation of state of
nuclear matter, which can be extended to describe neutron-star matter. With
knowledge of the masses of nuclides near shell closures, one can also derive
the neutron-star crustal composition. The Penning-trap mass spectrometer
ISOLTRAP at CERN-ISOLDE has recently achieved a breakthrough measuring the mass
of 82Zn, which allowed constraining neutron-star crust composition to deeper
layers (Wolf et al., PRL 110, 2013). We perform a more detailed study on the
sequence of nuclei in the outer crust of neutron stars with input from
different nuclear models to illustrate the sensitivity to masses and the
robustness of neutron-star models. The dominant role of the N=50 and N=82
closed neutron shells for the crustal composition is confirmed.
