Comet 72P/Denning–Fujikawa: down but not necessarily out

It is argued that Comet 72P/Denning–Fujikawa is an old and intermittently active comet evolving, at least observationally, towards a transitional minor planet status. We have studied the fate of hypothetical meteoroids ejected from the comet during its two known periods of activity (1881 and 1978). A complex history of orbital evolution is found. Meteoroids ejected in 1881 first become Earth‐orbit‐crossing in 1960, while meteoroids ejected in 1978 appear to hold stable, non‐Earth‐orbit‐crossing orbits until at least 2110. If copious amounts of meteoroids were ejected in 1881 we find some indication that the Earth may encounter a populous, coherent subgroup, or ‘streamlet’, of them in 2009 and 2010, leading to the possibility of outburst activity in those years. We have investigated the possibility that the activity of Comet 72P/Denning–Fujikawa, over the past ∼200 years, has been governed by impacts suffered by the comet as it moves through the main‐belt asteroid region. While encounters with centimetre‐sized objects will take place each time the comet orbits the Sun, the likelihood of the comet encountering a large metre‐sized asteroid is essentially zero on the time‐scales considered. The outburst activity of the comet may be impact‐modulated in the sense that small‐object impacts might trigger the explosive release of gases trapped in subsurface cavities.