Ricerc@Sapienza

In this paper, the feasibility of exploiting the Sun’s gravitational force to design the final
phase (capture and orbit circularisation) to Mercury with a low propellant consumption has
been investigated. The initial conditions, on the eccentricity and argument of pericentre, for
the circularisation phase are obtained from a prime integral of motion, which takes place
when the probe moves over a polar orbit. A numerical analysis has highlighted how these
initial conditions allow, under the third-body effect, an optimal reduction of eccentricity
(circularisation phase) with limited variations of the other orbit elements, without requiring
orbital manoeuvres. Then, by introducing a small velocity variation, the phase of ballistic
capture has been joined to the circularisation phase. The obtained results can encourage the
exploitation of this phenomenon in future missions for the exploration of Mercury.