The report describes results of an investigation of the propellant economies of using the gravitational attraction of Jupiter's four large moons to effect the transfer of a spacecraft into orbit around that planet. Use of a simplified model to approximate the maximum possible energy change as a function of the approach energy shows that the maximum energy loss from a flyby of Ganymede, the largest moon, is less than half that required to transfer from a high-thrust approach trajectory to an acceptable elliptical orbit. Thus, chemical retro-thrust is necessary to effect the transfer, and a moon swingby may not be justified. With a low-thrust trajectory approach, however, economical gravity assist from a moon is more promising. The lower approach energies of optimal low-thrust trajectories can be further reduced by retrothrusting, and guidance problems are more easily handled. A no-impulse capture could result in a final orbit with a one-year orbital period. Moreover, the relaxation of the required velocity endpoint conditions for low-thrust trajectories may allow significantly increased payloads or shorter flight times. (Author)
Gravity Assist from Jupiter'S Moons for Jupiter-Orbiting Space Missions
1968
48 pages
Report
Keine Angabe
Englisch
Spacecraft Trajectories & Flight Mechanics , Interplanetary trajectories , Space navigation , Orbital trajectories , Jupiter(Planet) , Transfer trajectories , Elliptical orbit trajectories , Flyby , Gravity , Asymptotic series , N-body problem , Numerical methods and procedures , Planetary orbits , Ganymede , Callisto , Two-body problem , Gravity assisted trajectories , Planetary satellites
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