TRAJECTORY OPTIONS TO PLUTO VIA GRAVITY ASSISTS FROM VENUS, MARS, ANDJUPITER

Analytic and numeric techniques are used to assess trajectory options for the Pluto Express sciencecraft for a launch early in the next deca de, The constraints placed on the Pluto Express trajectory for this st udy are severe-total flight time to Pluto of 12 years or less using a Delta-class launch vehicle. In addition, no flybys of Earth are permit ted. Suitable trajectories are found with launch windows before, near, and after the date of the baseline launch, All of these trajectories take advantage of a gravity assist with Jupiter, and all use two or th ree gravity assists with Venus before arriving at Jupiter. In two case s, a Mars gravity assist is used in conjunction with three Venus gravi ty assists. Several asteroid flyby opportunities are presented for the baseline mission and for a backup trajectory, which launch in March 2 001 and July 2002, respectively. For example, a flyby of the asteroid Seraphina (which has a radius of 32 km) can be accommodated in the bas eline mission for an additional deterministic delta velocity of 0.12 k m/s, well within the capability of the system.