Moon & Mars Orbiting Spinning Tether Transport - Tethers Unlimited

Appendix L: Tether Boost Facility Design Final ReportAnother design under consideration is using the waste heat to drive a Stirlingengine/ generator combination which would reduce the amount of waste heat to beremoved by radiators and would convert a large fraction of the waste heat into usefulwork to drive other subsystems. Stirling engines are currently being used in solarenergy conversion projects and we will be monitoring this technology to see if thereliability and life of the Stirling engine would be adequate.3.5.2 New Issues and Requirements IdentifiedRemoval of 35-40 Kw of concentrated heat has not been designed anddemonstrated in an on-orbit thermal control system. The International Space Stationused an active system with heat exchangers but is designed for much less wasteheat removal and much less waste heat density. Removal of concentrated wasteheat without incurring large mass penalties will require innovative techniques.3.5.3 Trades and Recommendations• Heat exchangers vs. Heat-pipes vs. combination of both• Mix of CCHP and VCHP configuration trades• Stirling engine usage and sizing3.5.4 Recommended Follow-on studies• Detailed Study of Sizing and Performance Trade-offs of Heat exchangersvs. Heat-pipes vs. combination of both• Detailed Study of Sizing and Performance of Mix of CCHP and VCHPconfigurations• Detailed Study of Stirling engine usage and sizing for conversion of wasteheat3.6 Structure/Configuration/Mass Properties3.6.1 Design Requirements, Drivers, and AssumptionsThe Control Station structure supports subsystem components, and protectsthese components from the launch environment and on-orbit loading environmentfrom Facility rotation. The Control Station must be configured to accommodate futureon-orbit expansion (mass addition) and will be composed of aluminum and compositestructures. Equipment bays will have aluminum isogrid shelves for mounting avionicsand routing cables. The deployable solar array supports will also have cable trays.Main design drivers are as follows:• Current Facility expansion concept (mass growth) — Drives placement ofarrays, radiators, and FEACs• Size of reel, CMG’s — Sizes equipment bays• Total PV array area — Drives launch configuration, and determines bulkof structure required to support gimbaled arrays and transmit on-orbitloadingL-66