  CubeSats offer a flexible and low-cost option to increase the scientific and
technological return of small-body exploration missions. ESA's Hera mission,
the European component of the Asteroid Impact and Deflection Assessment (AIDA)
international collaboration, plans on deploying two CubeSats in the proximity
of binary system 65803 Didymos, after arrival in 2027. In this work, we discuss
the feasibility and preliminary mission profile of Hera's Milani CubeSat. The
CubeSat mission is designed to achieve both scientific and technological
objectives. We identify the design challenges and discuss design criteria to
find suitable solutions in terms of mission analysis, operational trajectories,
and Guidance, Navigation, & Control (GNC) design. We present initial
trajectories and GNC baseline, as a result of trade-off analyses. We assess the
feasibility of the Milani CubeSat mission and provide a preliminary solution to
cover the operational mission profile of Milani in the close-proximity of
Didymos system.
