  Large angular scale surveys in the absence of atmosphere are essential for
measuring the primordial $B$-mode power spectrum of the Cosmic Microwave
Background (CMB). Since this proposed measurement is about three to four orders
of magnitude fainter than the temperature anisotropies of the CMB, in-flight
calibration of the instruments and active suppression of systematic effects are
crucial. We investigate the effect of changing the parameters of the scanning
strategy on the in-flight calibration effectiveness, the suppression of the
systematic effects themselves, and the ability to distinguish systematic
effects by null-tests. Next-generation missions such as LiteBIRD, modulated by
a Half-Wave Plate (HWP), will be able to observe polarisation using a single
detector, eliminating the need to combine several detectors to measure
polarisation, as done in many previous experiments and hence avoiding the
consequent systematic effects. While the HWP is expected to suppress many
systematic effects, some of them will remain. We use an analytical approach to
comprehensively address the mitigation of these systematic effects and identify
the characteristics of scanning strategies that are the most effective for
implementing a variety of calibration strategies in the multi-dimensional space
of common spacecraft scan parameters. We also present Falcons, a fast
spacecraft scanning simulator that we developed to investigate this scanning
parameter space.
