Spinning tethers for rapid orbital plane change

Abstract

I describe the use of a spinning tether to change the orbital plane of a payload via momentum exchange. In this concept, the tether’s rotation axis is roughly perpendicular to its orbital axis. At two points in the orbit, the tether rotates in the local horizontal plane. Near these two orbital locations, an orbiting spacecraft that attaches to a tether tip for half a rotation will be released into a new orbit that is at a substantial angle to the original orbit. The plane change angle for relatively small payloads and existing materials can easily exceed 28.5 degrees, enough to shift a payload launched due east from Kennedy Space Center to either an equatorial orbit or the orbit of International Space Station. Larger plane changes are achievable with lower safety factors or stronger materials. Attachment and release at different points in the tether rotation allows acceleration of sub-orbital payloads to orbital speed with little or no plane change. Though conceptually simpler in an equatorial or polar orbit, the system is able to operate in orbits with intermediate inclination. For a reasonable range of inclinations and rotation rates, gravity gradient torque causes rotational precession to keep pace with orbital precession. The angle between the orbital and rotational axes remains constant, so rendezvous opportunities are frequent.I describe the use of a spinning tether to change the orbital plane of a payload via momentum exchange. In this concept, the tether’s rotation axis is roughly perpendicular to its orbital axis. At two points in the orbit, the tether rotates in the local horizontal plane. Near these two orbital locations, an orbiting spacecraft that attaches to a tether tip for half a rotation will be released into a new orbit that is at a substantial angle to the original orbit. The plane change angle for relatively small payloads and existing materials can easily exceed 28.5 degrees, enough to shift a payload launched due east from Kennedy Space Center to either an equatorial orbit or the orbit of International Space Station. Larger plane changes are achievable with lower safety factors or stronger materials. Attachment and release at different points in the tether rotation allows acceleration of sub-orbital payloads to orbital speed with little or no plane change. Though conceptually simpler in an equatorial or polar or...