gravity assist maneuver in planetary programs

Paper number

IAC-08.E4.3.7

Author

Ms. Leila Khaladjzadeh, K.N. Toosi University, Iran

Coauthor

Prof. Mehran Mirshams, K.N.Toosi university of technology, Iran

Year

2008

Abstract

Gravity assist is a maneuver in which a spacecraft flies by a celestial body like a planet and uses its relative movement and gravity to alter the spacecraft's speed and path. Each gravity assist maneuver changes the shape, size and tilt of spacecraft's orbit and can add or subtract momentum to increase or decrease the energy of a spacecraft's orbit. Hiring such maneuvers leads to save fuel and time in a mission. 

The maneuver was first developed in 1959, and Mariner 10 was the first interplanetary spacecraft to use it in 1974, when passing by Venus to use its gravitational slingshot effect to reach Mercury. Since then, several robotic spacecraft have taken advantage of the gravity assist flyby technique to reach their targets of exploration in distant areas of the solar system.

The two Voyager spacecrafts provide a classic example of utilizing gravity assist flybys to reach their destinations. Voyagers gained the energy necessary for escaping the sun's gravity by performing slingshot maneuvers around Jupiter and Saturn. Before Voyagers, Pioneer 11 probe, following in its predecessor's footsteps, had passed by Jupiter and hired a new technique of gravity assist to take its first look at the planet Saturn. Following these, Galileo flew by Venus once and the Earth twice in order to reach Jupiter. Ulysses also used the giant planet's gravity to hurl itself into an orbit out of the ecliptic plane, allowed it to fly over the Sun's polar regions. Furthermore, Cassini-Huygens spacecraft has taken two assists from Venus, one from Earth, and another from Jupiter to gain enough momentum to reach Saturn. Stardust performed an Earth gravity assist flyby that enlarged its heliocentric orbit. And the most recent one, MESSENGER uses gravity assists from Earth, Venus and Mercury to lower its speed relative to Mercury to orbit around the small planet. Worth to mention New Horizons that is a mission designed to fly by Pluto and its moon Charon.

This paper describes how planetary gravity assist maneuvers, during about forty years of developing the technique, have been used to design trajectories of spacecrafts and save expenses which have enabled interplanetary missions. 

Abstract document

IAC-08.E4.3.7.pdf

Manuscript document

IAC-08.E4.3.7.pdf (🔒 authorized access only).

To get the manuscript, please contact IAF Secretariat.