In several comets, including the interstellar comet 3I/ATLAS, a non-gravitational acceleration is observed, i.e., a net thrust not fully accounted for by gravity. While outgassing is known to produce force, this alone does not fully explain two commonly observed features: (1) the non-gravitational acceleration often turns on and off abruptly rather than varying smoothly, and (2) these transitions appear to be temporally correlated with changes in the coma morphology (e.g., jet orientation and stability, asymmetric brightness contours). This behavior is difficult to reconcile with a purely gradual change in sublimation rate.
Data from Rosetta (67P) indicate that the nucleus surface is not homogeneous, but composed of porous aggregates, mechanically stressed structures, and evolving fractures. The ability to maintain a stable, directional jet pattern appears to depend on a minimum level of surface cohesion. If that cohesion decreases, the geometry of the outflow sources may reorganize abruptly without requiring a significant change in the total mass-loss rate. This could explain sudden shifts in thrust direction.
Under this view, the coma functions as a visible map of the outflow organization. A change in coma morphology would reflect a change in the cohesive structure of the surface. The net non-gravitational thrust would depend not only on the amount of outgassing but on its spatial asymmetry relative to the rotation axis.
My question is:
Are there published studies that explicitly interpret non-gravitational acceleration in terms of changes in mechanical surface cohesion or jet-organization structure, rather than solely in terms of sublimation rate variation? And have any works jointly analyzed rotation-state evolution, coma morphology, and non-gravitational acceleration time series to test for such transitions?
I am familiar with the Marsden NG formalism and Rosetta results on jet-driven torque and fracture evolution on 67P. I am asking specifically whether the hypothesis “surface cohesion change → jet pattern reorganization → abrupt thrust change” has been examined directly.
