The problem of close approach of two small masses in the field of massive oblate primary

The present work deals with the encounter problem of two small masses m2 and m3 describing initially elliptical orbits around a massive oblate primary. The equations of motion are developed, up to the power 13 of the small parameter, both for the center of mass and for the relative motion of m2 and m3 without any restrictions on the orbital elements. The equations of motion of the center of mass are expressed in terms of the Struble variables.