Refined dynamical analysis of multi-tethered satellite formations

The dynamics of a multi-tethered satellite formation is considered here, in order to derive a minimum complexity model that successfully represents its dynamics under the action of gravity gradient force and tether tension, where tethers are modeled by means of a sequence of point-masses and massless springs (bead model). The results thus obtained are compared with those derived for a simple, massless tether model, in order to highlight the effects of tether mass on the resulting open-loop behavior. The analysis is performed by means of numerical simulation of the considered models. Once the dynamic behavior of the formation is identified for the nominal values of tether characteristics, the problems raised by the presence of tether mass are highlighted and possible solutions are outlined, when possible. A parametric analysis with respect to the tether linear mass, damping and stiffness is also discussed.

► Multi-tethered formation is an emerging technology for future space missions.
► Open hub-and-spoke formations can be modeled by means of massless tethers.
► In closed formations centrifugal pull on outer tethers makes inner ones loose tension.
► This effect can be represented only by means of a massive tether model.
► The use of circular external tethers is suggested as a means for solving this issue.