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This conference presentation explores the impedance matching between Low Earth Orbit (LEO) and Beyond Earth Orbit (BEO) transportation systems. Challenging the analogy of LEO as Earth's harbor, it argues that commercial companies will not tow vessels from Earth’s surface, advocating instead for a better analogy of shallow-draft boats in a deep harbor. It examines the stark differences in vehicle requirements between atmospheric operations on Earth and the vacuum of space. Additionally, the discussion emphasizes how innovative architecture can optimize access to LEO, improve propulsion efficiencies, and address orbital mechanics constraints.
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Rand Simberg Wyoming Aerospace Space Access Conference April 9, 2010 Phoenix, AZ Impedance Matching Between LEO And BEO
LEO As A Harbor • Recent Quote From Pete Worden: “You can look at low Earth orbit as Earth's harbor, and you don't need a government tug boat company anymore.“ • Is This A Good Analogy?
Harbor Tug Analogy Has Problems • Commercial Companies Aren't Going To Guide Or Tow Space-Faring Vessels To/From Earth Surface (Tug Analogy) • Anchoring In Deep Harbor With Shallow-Draft Boats For Access Better Analogy • Harbor Is Atmosphere, Earth Is Dock • BEO Is Ocean
Vehicle Requirements Conflict • Earth-LEO-Return Has Dramatically Different Requirements Than In-Space Transportation • Earth/LEO – High T/W, Atmospheric Operations, Extreme Aerothermodynamics, High Structural Stress (Small Speedboat) • In-Space – Varying T/W, Vacuum, Little/No Atmospheric Interaction, Orbital Mechanics, Low Structural Stress (Ocean Liner) • Aeronautics Versus Astronautics • Having To Do Both With Single Vehicle Gets Very Expensive (e.g., Apollo, Shuttle) • Have To Interface Them In LEO (Part of “Impedance Matching”)
The Ideal Scenario • The Clarke Vision • Pan Am Shuttle For ETO And Back • LEO Space Facility For Transit • Lunar (And Beyond) Excursion Vehicles • (At Least) Two Problems • Fitting Through The LEO Portal • Getting To The LEO Portal
Fitting Through The Portal • ISS Was Extruded Through A Five-Meter Hole • Lots Of Programmatic Stiction/Friction • Probably Cost $20M Per Foot (~1500 feet) • We Should Be Able To Do Better • What Is The Minimum Maximum Diameter? • What drives it? Optics? Tankage? • Do We Need Not “Heavy Lift,” But Really-Wide Fairing? • How To Deliver Items To Ocean Liner With Speedboat?
Getting To The Portal • How Accessible Is LEO From BEO? • Orbital Mechanics Constraints • Delta Vee Issues • Do All Paths To LEO Go Through Earth Surface? • Can We Innovate Architecture To Allow LEO Return Via Aerobraking? • Can We Make In-Space Propellant Cheap Enough For Propulsive Circularization?