  Atom interferometry is an exciting tool to probe fundamental physics. It is
considered especially apt to test the universality of free fall by using two
different sorts of atoms. The increasing sensitivity required for this kind of
experiment sets severe requirements on its environments, instrument control,
and systematic effects. This can partially be mitigated by going to space as
was proposed, for example, in the Spacetime Explorer and Quantum Equivalence
Principle Space Test (STE-QUEST) mission. However, the requirements on the
instrument are still very challenging. For example, the specifications of the
STE-QUEST mission imply that the Feshbach coils of the atom interferometer are
allowed to change their radius only by about 260 nm or 2.6E-4% due to thermal
expansion although they consume an average power of 22 W. Also Earth's magnetic
field has to be suppressed by a factor of 10E5. We show in this article that
with the right design such thermal and magnetic requirements can indeed be met
and that these are not an impediment for the exciting physics possible with
atom interferometers in space.
