Moon & Mars Orbiting Spinning Tether Transport - Tethers Unlimited

Appendix L: Tether Boost Facility Design Final Report5.2 Sub-Scale Electrodynamic Tether Propulsion Flight ExperimentWhile substantial data exists that strongly suggests ED tether propulsion will workas predicted, to date a flight experiment has not been conducted to verify this. An EDflight experiment should verify not only the basic concept but also associated factorsand modes of operation as well (e.g., station keeping and altitude raising) to bring mostelements of an ED tether transport system to TRL 6. The objectives of an ED tetherflight experiment should include:• Verify models of high-current contact between FEACs and the ionosphere.• Validate high-power, high-voltage electrical systems.• Measure FEAC lifetime.• Validate systems and procedures for ED tether reboost and deboost.• Validate systems and procedures to maintain tether tension and configurationwithin acceptable limits in all flight regimes.• Verify capability for a full range of collision avoidance maneuvers.Optional tasks such as orbit phase adjustment may also be verified. Also EDtether issues, such as off-angle thrust, out-of-plane libration, and the shifting of thevehicle center of mass will be verified as to the predicted magnitude of effects.An ED tether flight experiment would need an ED tether of at least 4-5 km inlength and enough power to adequately demonstrate the mission parameters describedpreviously. Power requirements would depend on size of the flight experiment, but akilowatt or more of power would be required to adequately perform the required flighttests. An operational life of a few days may be adequate to meet the basicrequirements, but a longer life to demonstrate or verify some tether concepts andconcerns is preferred. Tether life in the predicted LEO environment of atomic oxygenand ultraviolet light has been a recent concern. A long term flight experiment couldaddress basic tether material questions as well as ED tether propulsion; however, thisapproach is not considered a requirement for the ED tether flight experiment.Several flight design configurations are possible to demonstrate ED tetherpropulsion. The most obvious option, and probably the best technical launch option, isto use an ED tether to launch a small satellite. This would require a dedicated launchvehicle, thus the most costly option when the launch vehicle cost is added in (e.g.,$20M and up). Even using a secondary PAF (Payload Adapter Fitting), the ED tetherportion of cost for the launch vehicle can easily exceed $10 million (possiblyconsiderably more).Alternative lower cost or near zero cost launch options were explored, such ariding in the avionics shelf of an expendable vehicle, such as a Delta II or IV, or usingone of the many Space Shuttle options. Table 5-1 lists some possiblecarrier/deployment options.The two best options appear to be the Delta IV avionics shelf and a Shuttle carriersuch as the Hitchhiker. Hitchhiker at first glance is the better option, it can provideadequate power for an ED tether at up to 1500 watts and additional costs like avionicsF-29