  A major challenge common to all Galilean drop tests of the Universality of
Free Fall (UFF) is the required control over the initial kinematics of the two
test masses upon release due to coupling to gravity gradients and rotations. In
this work, we present a two-fold mitigation strategy to significantly alleviate
the source preparation requirements in space-borne quantum tests of the UFF,
using a compensation mechanism together with signal demodulation. To this end,
we propose a scheme to reduce the gravity-gradient-induced uncertainties in an
atom-interferometric experiment in a dedicated satellite mission and assess the
experimental feasibility. We find that with moderate parameters, the
requirements on the initial kinematics of the two masses can be relaxed by five
orders of magnitude. This does not only imply a significantly reduced mission
time but also allows to reduce the differential acceleration uncertainty caused
by co-location imperfections below the $10^{-18}$ level.
