Interplanetary Trajectories for Multiple Satellite-Aided Capture at Jupiter

Abstract

Multiple-satellite-aided capture employs sequential gravity-assist flybys of more than one of Jupiter’s Galilean moons. These flybys substantially reduce the amount of propellant required for a spacecraft to capture into orbit around Jupiter. The “average” plane of the Galilean satellites constrains the arrival V-infinity vector, which in turn constrains the interplanetary trajectories from Earth to Jupiter. The solution space of interplanetary trajectories that permit multiple-satellite-aided capture is explored, and trajectories that start from Earth and end at Jupiter capture are integrated. I. Introduction Satellite-aided capture is a mission design technique that is used to decrease the V required to capture a spacecraft into orbit around a planetary body. The technique employs gravity-assist flybys of massive satellites of a planetary body, so only missions to planets with large moons can benefit from this technique. Hence, satellite-aided capture is only available to Earth-return missions and missions to Jupiter, Saturn, Uranus, or Neptune. Jupiter, in particular, has four massive Galilean moons that can be used for satellite-aided capture. These satellite-aided capture trajectories were first proposed for missions to Jupiter by Longman 1 and by Longman and Schneider. 2 Cline 3 determined the best use of a Ganymede gravity-assist to minimize the Jupiter insertion maneuver (JOI) V required for capture into Jupiter orbit. Nock and Uphoff 4 performed a tour-de-force of satellite-aided capture trajectories for the entire Solar System by varying several trajectory parameters, including perijove radius after flyby, flyby altitude, declination of the incoming satellite-centered hyperbola, and the distribution of V between powered satellite flybys and the JOI maneuver. They also briefly investigated double-satellite-aided capture by determining the phasing and transfer orbit parameters necessary to achieve capture. Malcolm and McInnes 5 employ a vectorial targeting approach to solve the satellite-aided capture problem. Yam 6 and Okutsu et al. 7 present a central-body-changing algorithm that can model a satellite-aided capture using a patched-conic method. The algorithm accepts a planet-centeredV1 vector and a moon’s radius vector as input and outputs the phase angle between the incoming Jupiter-centered asymptote and the flyby. Landau et al. 8 proposed using solar electric propulsion (SEP) to reduce the Jupiter arrivalV1 of interplanetary trajectories in order to ballistically capture an SEP spacecraft into orbit about Jupiter with gravity assists of one or two of Jupiter’s Galilean moons. The first implementation of a single-satellite-aided capture occurred during the Galileo mission to Jupiter. 9 Two proposed NASA missions to Jupiter (the Europa Orbiter Mission 10‐12 and the Jupiter Icy Moons Orbiter 13 ) had designed single-satellite-aided capture trajectories using Ganymede and Callisto, respectively. The planned Jupiter Europa Orbiter mission has a nominal trajectory that includes an Io-aided capture. 14 Lynam et al. 15 proposed the use of double-, triple-, or quadruple-satellite-aided capture as another method of capturing a spacecraft into orbit around Jupiter with still lower V cost. That study focuses on the Jupiter capture phase of these trajectories and only briefly discusses the interplanetary trajectory phase of these missions. In this paper, we connect several of the multiplesatellite-aided capture sequences designed by Lynam et al. with interplanetary trajectories to form complete trajectories from Earth launch to Jupiter capture. Figure 1 shows a complete trajectory that begins at Earth launch and then performs gravity-assist flybys of Ganymede and Io as it approaches Jupiter. We also determine how often some of these capture trajectories are available for use in a future mission and how much total mission V can be saved. As in Lynam et al., we assume that the (non-trivial) navigational challenges associated with these trajectories can be surmounted.