Determine whether launched dust escapes or falls back onto the nucleus

Determine whether the dust particles launched by the two-layer outgassing and dust-ejection model for comet 67P/Churyumov–Gerasimenko ultimately escape the cometary system or fall back onto the nucleus.

Background

The model calculates the mass flux and size distribution of dust particles at launch but does not propagate those particles after ejection. Consequently, its predicted dust flux represents launched material rather than material known to have escaped the nucleus.

The distinction is central to interpreting comparisons with Rosetta dust measurements and to constructing the intended coupled activity-fallback model, because fallback can modify the local dust-crust depth and thereby alter subsequent outgassing and ejection activity.

References

Note that we do not track the dust after ejection, so strictly speaking this is only `launched' dust and we cannot currently say whether it is truly ejected from the comet system, or eventually falls back on the nucleus.

— Towards a coupled activity-fallback model for comets I) 67P/Churyumov-Gerasimenko's water activity from a microphysics model with dynamic dust-depth  (2610.13230 - Attree et al., 9 Oct 2026) in Section 3, Results, discussion of Figure 3