A contingency trajectory analysis was performed for NASA Ames Research Center's (ARC's) Lunar Atmosphere and Dust Environment Explorer (LADEE) spacecraft in case of a missed lunar orbit insertion (LOI) maneuver. Recovery trajectory options are shown to exist for all LADEE launch opportunities throughout a one year period. Recovery ΔV costs primarily depended on the spacecraft's apogee location on or near the Sun-Earth weak stability boundary (WSB) and the time needed by the spacecraft to recover (e.g. to "wake up" from "safe" mode) to perform an escape prevention maneuver after the missed LOI.
NomenclatureΔV = delta-V, change in velocity (m/s) Apogee = spacecraft's farthest point from Earth while in orbit C3 = (Earth) orbit Keplerian energy or the square of relative asymptotic (Earth) velocity (km 2 /s 2 ) IP = in-plane, with regard to a nominal solution's inclination in Earth's equatorial plane LOI = lunar orbit insertion (m/s) OP= out-of-plane, with regard to a nominal solution's inclination in Earth's equatorial plane Perigee = spacecraft's point of closest Earth approach while in orbit WSB = weak stability boundary: First mentioned as "stability boundary" by Belbruno 1 and changed to "weak stability boundary" 2, 3 (alternately known as "fuzzy boundary" 4 ), the WSB is a complex region (and fractal set) in six dimensional space and is the approximate transition region between negative (temporary capture; stable set) and positive (escape; unstable set) Keplerian orbit energy (i.e., C3) with respect to the primary body. The WSB can be represented by invariant manifolds and approximated by zero-velocity curves [5][6][7][8][9][10][11] . WSB transfer = a transfer that contains negative Keplerian energy (C3) and passes on or near the WSB
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