A DESIGN METHOD FOR LOW ALTITUDE, NEAR-EQUATORIAL LUNAR ORBITS

In 2013 the Lunar Atmosphere & Dust Environment Explorer (LADEE) mission will return to an orbital regime not visited since Apollo. The lunar orbit required for LADEE poses unique challenges to the mission designer: low, retrograde, near circular, near equatorial, 100 days duration, with the line of apsides aligned near the solar terminator. Due to the close proximity to the surface, the lunar gravity creates havoc on the LADEE orbit, perturbing the eccentricity and line of apsides while the semi-major axis remains largely unchanged. LADEE uses a novel, visual approach to allow the orbit designer to predict altitude decay and shifts in argument of periapsis and to plan orbit maintenance maneuvers.