Contour Mission Overview And Trajectory Design

A Discovery-class mission called the Comet Nucleus Tour (CONTOUR) is proposed. The baseline mission plan calls for flybys of three comets over a five-year period. Two launch opportunities are identified; one in July 2002 and another in July 2003. The first comet encounter would occur in November 2003 (Encke), the second in June 2006 (Schwassmann-Wachmann-3), and the third in August 2008 (d'Arrest). Five Earth gravity-assist maneuvers are used to construct the baseline multi-comet trajectory sequence. It is shown that, by using a small propulsive maneuver (Delta V similar to 54 m/sec) and two additional gravity-assist maneuvers, it is possible to achieve a second encounter with comet Encke in October 2013. Finally, it is shown that, by using different combinations of Earth gravity-assist maneuvers, it is possible to substantially alter CONTOUR's baseline trajectory. With a modified trajectory, the d'Arrest encounter could be replaced by an encounter with either comet Wirtanen in February 2008 or the dormant comet Wilson-Harrington in September 2009. It might also be possible to intercept a bright first-apparition comet.