Comet Enthusiast

I believe a crystallizing, perhaps consensus, idea is that Hartley 2 is a contact binary (which resembles comets Borrelly and perhaps Halley, perhaps making this a usual conformation). The smooth part would then be kept and transported ejecta from jets and impacts that assembled in, and now delineates, the gravitational well in between. A lot of funny things may happen in, perhaps, 4.5 Gy (life, for one).

A test for that hypothesis is that the jets are extinguished in that area.