“…Small bodies of the Solar system (asteroids, trans-Neptunian objects, cometary nuclei, planetary satellites) with diameters less than one thousand kilometers usually have strongly irregular shapes (Melnikov & Shevchenko 2010;Jorda et al 2016, p. 270), in many cases resembling dumb-bells, or "contact binaries". Various models for gravity fields of the "central body" were used: that of a triaxial ellipsoid with uniform density (Chauvineau et al 1993;Mysen et al 2006;Olsen 2006;Mysen & Aksnes 2007), a rod (Bartczak & Breiter 2003), a dumb-bell or "bilobed" model (Marchis et al 2014;Feng et al 2016), a collection ("molecule") of gravitating points (Petit et al 1997), a polyhedral model (Werner 1994;, a truncated gravitational field derived from a shape model (Feng et al 2017). Orbits around actual small bodies, such as asteroids Castalia, Eros, and Hektor were extensively modeled (Scheeres et al 1996(Scheeres et al , 2000Marchis et al 2014;Yu & Baoyin 2012).…”