A characterization of rotational minimal surfaces in the de Sitter space

The generating curves of rotational minimal surfaces in the de Sitter space $\s_1^3$ are characterized as solutions of a variational problem. It is proved that these curves are the critical points of the center of mass among all curves of $\s_1^2$ with prescribed endpoints and fixed length. This extends the known properties of the catenary and the catenoid in the Euclidean setting.