Many worlds exist in the solar system with salty subsurface liquid-water oceans beneath icy crusts, facilitated by surface tidal and librational heating. Saturn's moons Enceladus and Titan are known to be water-ocean worlds. Enceladus exhibits impressive jets of water vapor that spray from fissures in the south pole region (Porco et al., 2006), likely the result of tidally driven fault-motion heating of water sourced from a global or regional subsurface ocean below a thick ice shell (Nimmo et al., 2007). Time-varying magnetic induction signatures measured by Galileo's magnetometers in the vicinity of Jupiter's moons Europa and Callisto suggest these bodies also have salty liquid-water oceans beneath their surfaces (

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Many science missions require an unobstructed view of space and a stable thermal environment but lack the technical or programmatic resources to reach orbits that satisfy these needs. This paper presents a high Earth orbit in 2:1 resonance with the Moon that provides these conditions, reached via lunar gravity assist. Analytical guidance and numerical investigation yielded deep insight into this unconventional orbit's behavior, making it possible to select a robust mission design. Solutions are available for a broad range of missions, from smaller Explorer-class missions such as the Transiting Exoplanet Survey Satellite to larger missions that seek lower-∆V alternatives to traditional Lagrange-point, drift-away, and geosynchronous orbits.

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