Moon & Mars Orbiting Spinning Tether Transport - Tethers Unlimited

Tethers Unlimited, Inc.Cislunar Tether Transportlaunch large quantities of propellant into Earthorbit.SummaryOur analyses have concluded that the optimumarchitecture for a tether system designed totransfer payloads between LEO and the lunarsurface will utilize one tether facility in anelliptical, equatorial Earth orbit and one tetherin low lunar orbit. We have developed a systemconcept design for a 100 km long Earth-orbitTether Boost Facility capable of picking 1,000 kgpayloads up from LEO and injecting them into aminimal-energy lunar transfer orbit. This systemwill also boost 2,500 kg payloads to GTO. Thepayload capacity of the system can be builtincrementally by deploying additional tethermodules. After boosting a payload, the facilitycan use electrodynamic propulsion to reboost itsorbit, enabling the system to repeatedly sendpayloads to the Moon without requiringpropellant or return traffic. When the payloadreaches the Moon, it will be caught andtransferred to the surface by a 200 km long lunartether. Using two different numericalsimulations, we have tested the feasibility ofthis design and developed scenarios fortransferring payloads from a low-LEO orbit tothe surface of the Moon, with only 25 m/s of ∆ Vneeded for small trajectory corrections. Thus, i tappears feasible to construct a Cislunar TetherTransport System that can greatly reduce the costof round-trip travel between LEO and the surfaceof the Moon by minimizing the need forpropellant expenditure.AcknowledgmentsThis research was supported by Phase I andPhase II grants from NASAÕs Institute forAdvanced Concepts. The author wishes toacknowledge significant input by ChaunceyUphoff of Fortune Eight Aerospace, and valuablediscussions with Kirk Sorensen of NASA/MSFC.References1. Hoyt, R.P. Uphoff, C.W., ÒCislunar Tether TransportSystemÓ, J. Spacecraft and Rockets, 37(2), March-April 2000, pp. 177-186.2. Hoyt, R.P., ÒCislunar Tether Transport SystemÓ,Tethers Unlimited, Inc. Final Report on NASAInstitute for Advanced Concepts Phase I Contract07600-011, May 1999. Downloadable fromwww.niac.usra.edu.3. Forward, R. L., ÒTether Transport from LEO to theLunar Surface,Ó AIAA paper 91-2322, July 1991.4. Hoyt, R. P., Forward, R. L., ÒTether System forExchanging Payloads Between Low Earth Orbitand the Lunar SurfaceÓ, AIAA 97-2794, July 1997.5. Danby, J.M.A., Fundamentals of Celestial Mechanics,2 nd Edition, Willmann-Bell, 1992, Ch. 14.6. Failure Resistant Multiline Tether, Robert L. Forwardand Robert P. Hoyt, PCT/US97/05840, filed 22April 1997.7. Mart’nez-S‡nchez, M., Gavit, S.A., ÒOrbitalModifications using Forced Tether LengthVariationsÓ, Journal of Guidance, Control, andDynamics, 10(3) May-June 1987, pp 233-241.8. Hoyt, R. P., ÒMaintenance Of Rotating Tether OrbitsUsing Tether ReelingÓ, Appendix F in Ref. 2.9. Moravec, H., ÒA Non-Synchronous Orbital Skyhook,ÓJournal of the Astronautical Sciences., 25(4), Oct-Dec1977, pp. 307-322.10. Landis, G.A., ÒReactionless Orbital Propulsionusing Tether Deployment,Ó Acta Astronautica 26(5),IAF Paper 90-254, 1992.11. Kim, E., Vadali, S.R. ÒModeling Issues related toRetrieval of Flexible Tethered Satellite Systems,ÓJournal of Guidance, Control, and Dynamics, 18(5),1995, pp 1169-76.12. Uphoff, C., ÒMission Analysis Evaluation andSpace Trajectory Optimization ProgramÓ, FinalReport on NASA Contract NAS5-11900, March1973.11