Abstract
It is well known that the 3-D motion around the asteroid (433) Eros is chaotic for a wide set of inclinations. The main feature of this body is its elongated shape, which originates that the usual procedure of expanding the potential function in spherical harmonics is useless. This is the reason why we consider a simple model to describe its elongated shape, namely, a rotating finite straight segment. By so doing, it is possible to obtain the potential in closed form, with no need of further expansions. For this model, from the analysis of families of periodic orbits, we can find an explanation for most of dynamics already found for orbits around Eros.
