Open Space Elevator Cable: A Multilayer CNT-Graphene Tether Blueprint for 100 km Demonstrator

We present the first open-source engineering roadmap for a carbon-nanotube (CNT) / graphene composite tether capable of supporting a 100 km sub-orbital space-elevator demonstrator. Built on a multilayer architecture—Bio-Skin-DSUP, Waterbomb origami impact absorbers, NiTi SMA vibration control, CoolWave hydro-ducts, CNT/graphene core, and KCR-Lens fibre sensors—the design targets a tensile strength ≥ 45 GPa at a linear mass density of 0.98 kg km⁻¹. We detail material processing, layer integration, test protocols, and phased deployment scenarios. An open Bill-of-Materials and partner matrix are provided to catalyse collaborative R&D toward a full orbital elevator.