Dictionary of Space Concepts

Source: http://solarsystem.nasa.gov/multimedia/display.cfm?IM_ID=2143, https://commons.wikimedia.org/w/index.php?curid=18049439

Short Definition:

Gravity assistance describes the intentional use of the gravitational attraction of a celestial body, in order to modify the trajectory of a space vehicle. This maneuver allows the spacecraft to save rocket fuel.

Detailed Definition:

Etymology:

1. Gravity (Noun.), originating from the Latin word gravitatem, with the meaning of “weight, heaviness, pressure”

2. Assist (Verb.), originating from Latin word assistere, which means “standing by, help”

Sample Sentence(s):

“The global minimum velocity increments of direct transfer trajectory and gravity-assist trajectories are obtained for each candidate target.”

Translations:

• French: Assistance gravitationnelle
• German: Schwerkraftumlenkung
• Polish: Asysta grawitacyjna
• Swedish: Gravitationsslunga

Links to Videos/Articles:

1. "Section 1: Environment, Chapter 4: Trajectories". Basics of Space Flight. NASA. 
   
2. "Gravity assist". The Planetary Society.