  The Satellite for Orbital Aerodynamics Research (SOAR) is a CubeSat mission,
due to be launched in 2021, to investigate the interaction between different
materials and the atmospheric flow regime in very low Earth orbits (VLEO).
Improving knowledge of the gas-surface interactions at these altitudes and
identification of novel materials that can minimise drag or improve aerodynamic
control are important for the design of future spacecraft that can operate in
lower altitude orbits. Such satellites may be smaller and cheaper to develop or
can provide improved Earth observation data or communications link-budgets and
latency. Using precise orbit and attitude determination information and the
measured atmospheric flow characteristics the forces and torques experienced by
the satellite in orbit can be studied and estimates of the aerodynamic
coefficients calculated. This paper presents the scientific concept and design
of the SOAR mission. The methodology for recovery of the aerodynamic
coefficients from the measured orbit, attitude, and in-situ atmospheric data
using a least-squares orbit determination and free-parameter fitting process is
described and the experimental uncertainty of the resolved aerodynamic
coefficients is estimated. The presented results indicate that the combination
of the satellite design and experimental methodology are capable of clearly
illustrating the variation of drag and lift coefficient for differing surface
incidence angle. The lowest uncertainties for the drag coefficient measurement
are found at approximately 300 km, whilst the measurement of lift coefficient
improves for reducing orbital altitude to 200 km.
