Influence of a small end mass on tether-mediated orbital injection

The tether-assisted slingshot injection allows raising the apogee up to abo ut 14 tether lengths, depending on the angular speed, whereas the perigee o nly rises by one,tether length. With a two-cut procedure, the tether depart s with the satellite at the first cut and is discarded close to the apogee, so that the momentum transferred by the tether provides an additional rais ing of the perigee. This results in a longer lifetime. The disadvantages ar e that typical tethers are light and can transfer little momentum at the se cond cut and that libration with a free end is highly unstable. With zero t ension at the tip, perturbations easily propagate and the rectilinear shape is lost. A modification is proposed that improves on both counts, leaving a mass attached to the free end of the tether. It can be part of the deploy er assembly, so that no additional weight is needed. This increases the mom entum transferred at the second cut, thus raising drag-sensitive perigee. E ven small masses appreciably increase in lifetime. Tether tension is higher , so that libration is more stable and the rectilinear shape is preserved f or a longer time. The new mass distribution changes the frequencies of the tether oscillations and can be used to avoid resonances.