A novel tether-net configuration with double-linked bullets for suppressing reshrinking motion after full deployment

Tether-nets have attracted considerable attention as tools for capturing space debris. However, owing to the lack of aerodynamic drag to resist collapse in space, tether-nets tend to shrink back after deployment because of tension in the tether. Various strategies have been proposed to suppress this reshrinking motion before debris capture, such as equipping bullets with thruster modules to control their trajectory after ejection and incorporating a bullet ejection-angle adjustment mechanism. However, these approaches complicate the tether-net design and/or ejection systems. In this study, a novel tether-net configuration comprising double-linked bullets, wherein the inner and outer bullets are connected via a tether, was proposed to prevent the tether-net from reshrinking after full deployment. Upon full deployment, as the bullets start to rebound due to impulsive tension, the outer bullets fly outward, pulling the inner bullets and exchanging momentum to suppress their rebounding motion. The effectiveness of the double-linked bullets in suppressing the reshrinking motion of the tether-net was demonstrated by comparing the results with those obtained using typical single-linked bullets. Furthermore, the influence of the inner and outer bullet mass ratio on the tether-net deployment and reshrinking motion was numerically analyzed to identify the optimal mass ratio for effectively suppressing the reshrinking motion. The results indicate that a mass ratio of 1.0, or slightly less, between the outer and inner bullets is most effective in suppressing tether-net reshrinking.