Planetary ejection of a comet
= Planetary ejection of a comet
A <gravitational assist> ejects a weakly bound <comet> when the increase in its <specific orbital energy> exceeds its binding energy. For near-parabolic coplanar encounters, the weak-deflection ejection <impact parameter> scales as $(M_p/M_\star)Q$. Combining this with the <phase-mixed comet surface density> gives a one-encounter ejection time proportional to $Q^{1/2}$, within the local two-body encounter approximation.