= Solution
The two-boundary map omits several effects that can alter <planetary scattering>.
The initial <semi-major axis>, <orbital eccentricity>, <orbital inclination> and <orbital phase> determine whether encounters occur and their relative <velocities>. A strongly bound <comet> needs more <energy> to escape; a nearly parabolic one needs less. The planetary radius and <mass density>, the finite <comet> radius, and <gravitational focusing> determine collision probabilities. <Tidal disruption>, atmospheric <gas drag>, <sublimation> and physical fragmentation can destroy a body before a nominal point-particle scattering sequence is completed.
Other <planets> can hand a <comet> from one scatterer to another, eject it, or lift its <periapsis> clear of the original scatterer's <orbit>. <Mean-motion resonances> and <secular perturbations> can protect objects from encounters or correlate kicks, contradicting the independent <random walk> assumption. <Planetary migration> changes the encounter geometry over time.
<Stellar flybys> and a <galactic tide> can change distant <comet> <periapses>, allowing new encounters or detaching an object from the planetary region. Stellar <mass> evolution changes both binding and planetary <orbits>. Finally, the age and the supply rate of new <comets> determine whether the observed population is a residual one or continuously replenished. Thus the mass-radius map is a useful conditional classification, not a complete survival law.
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