Moon & Mars Orbiting Spinning Tether Transport - Tethers Unlimited

Tethers Unlimited, Inc.MMOSTT Final Reportcan be flown to provide reliability statistics, but to date only the Shuttle has re-used rocketengines, with significant maintenance after each flight. In a tether transportation system, thetether facility could be tested many times with “dummy” payloads – or, better yet, with lowinherent-value payloads such as water or fuel – to build confidence for use on high value ormanned payloads. In addition, "using" a tether does not damage or "wear it out", as long as theloads placed on the tether do not approach the yield point of the tether material. This meansthat the tether used in the operational system is the same tether in nearly the same condition inFigure 3. The Cislunar Tether Transport System concept.which it underwent strength and reliability testing with the "dummy" payloads.D. Summary of Phase I ResultsIn the Phase I effort, we investigated the feasibility of designing tether transportarchitectures for travel between LEO, the Moon, and Mars. We developed a design for aCislunar Tether Transport System that uses one tether in elliptical, equatorial Earth orbit andone tether in low lunar orbit to provide round-trip travel between LEO and the surface of theMoon. This design, illustrated in Figure 3, includes considerations for finite tether facilitymasses, the complicated Earth-Moon orbital geometry, and the behavior of orbits in the nonidealgravitational potentials of the Earth and Moon. We found that, using currently availabletether materials, such a system would require a total mass of less than 28 times the mass of thepayloads it can handle. Because a rocket-based system would require a propellant mass of atleast 16 times the payload mass to perform the same job, the fully-reusable tether system wouldbe competitive from a mass perspective after only two trips, and would provide large costsavings for frequent round-trip travel. Using numerical simulation tools with detailed models4