The Planetary and Space Science issue for 1 Oct (vol. 265) includes:
Gallot, T. Sedofeito, C. Ginares, A. et al. Seismic wave experiments in granular media with applications to asteroids Art 106153 .2025.106153
Barbieri, C. Beolchi, A. Bertini, I. et al. Preparing for the 2061 return of Halley’s comet. A rendezvous mission with an innovative imaging system Art 106165 .2025.106165
Bertini, I. Vincent, J-B. Marshall, R. et al. A composite phase function for cometary dust comae Art 106164 .2025.106164
The bad news is that typical comets don’t return for years, often decades (or longer). The good news is that we have lots of time to prepare for (returning) comets. Here’s Barbieri et al. preparing for yet another apparition of perhaps mankind’s most celebrated single comet. Considering the last (~1985) apparition was well-studied, by both Earth telescopes and an array of probes, we can get before and after comparisons. In this case, the authors plan on a fisheye camera (not all that innovative, I must say) to regularly map the comet coma, while keeping the nucleus in view.
The reason that the authors are publishing this paper now is that 2061 is not that far away, comet-wise. The plan is to send a probe into a comet-like orbit (like Rosetta did), and not just a quick flyby at one point in the comet path (like the prior Halley missions). In order to reach a comet-like orbit, the mission requires both a Jupiter flyby, and a low-thrust, electric rocket. Getting into a Halley-like orbit, including a Jupiter flyby to get in position, means launch in 2040, not just before 2061. If a significant mission is to be built and launched by 2040, we should start discussions soon.
The other two papers are (far) more general and extensible. Gallot et al. consider the dynamics of particle swarms in the form of rubble-pile asteroids: Itokawa, Ryugu, Bennu, and almost certainly Mathilde. This is non-obvious, because Earth piles are subject to gravity, air resistance, moisture, etc. Bertini et al. consider the effects of photons among comet comae. Again, we can’t just make terrestrial assumptions about what’s happening in space. The average comet coma is still less dense than the contaminants in a cleanroom on Earth. The comet looks like it’s shrouded in fog because we’re comparing it to the emptiness of space. Above a certain Earth altitude, space is a harder vacuum than the hardest vacuum ever pulled by mankind. Woe be he who thinks that a comet coma is actually thick, because it looks thick.