Gravitationel slynge

En gravitationel slynge (på engelsk kaldet gravity assist (flybys), der betyder forbi-flyvninger - og gravitational slingshots) er et begreb, der bruges om et rumfartøjs udnyttelse af gravitationen fra de himmellegemer det passerer til acceleration eller deceleration. Formålet er fx at spare brændstof og komme hurtigere frem til målet, planlægningen af sådan en rejse laves ud fra matematiske beregninger. Det er himmellegemets masse, der bestemmer hvor stor gravitation den har - og fartøjets mindsteafstand til planeten har betydning for, hvor stor effekt planetens gravitation får udøvet. Nogle gange passeres Lagrange-punkter for at komme i "stilling" til nyttige gravitationelle slynger.^[1]

Den gravitationelle slynge blev opdaget af Michael Minovitch (allerede da han var studerende) og præsenteret for Jet Propulsion Laboratory i form af en 47-siders teknisk artikel dateret d. 23. august 1961. ^[2]

^ "From Stargazers to Starships" -- Site Map: (35) Starships Citat: "...What the public might not have realized was that not only were these planets worthy targets for exploration, but their gravity pulls were an essential ingredient making this "grand tour" possible...This sort of maneuver is often used by interplanetary probes. Encounters with the Moon have also been used, for sending spacecraft towards the Lagrangian L1 point or the L2 point in the tail, for modifying missions (such as that of Geotail) and on December 22, 1983 for sending ISEE-3 away from Earth towards Comet Giacobini-Zinner...In this manner the stars nearest to Earth might be reached..."
^ gravityassist.com: The Creation of a new Theory of Space Travel -- Gravity Propelled Space Travel Citat: "...When Minovitch presented it to JPL in the form of 47 page technical paper dated August 23, 1961, it was dismissed by the head of JPL’s Trajectory Group as impossible...How could a young graduate student in mathematics and physics who never studied the problem of space propulsion, space travel or astrodynamics before the summer of 1961 ever invent a completely new theory of space travel..."

[1] "From Stargazers to Starships" -- Site Map: (35) Starships Citat: "...What the public might not have realized was that not only were these planets worthy targets for exploration, but their gravity pulls were an essential ingredient making this "grand tour" possible...This sort of maneuver is often used by interplanetary probes. Encounters with the Moon have also been used, for sending spacecraft towards the Lagrangian L1 point or the L2 point in the tail, for modifying missions (such as that of Geotail) and on December 22, 1983 for sending ISEE-3 away from Earth towards Comet Giacobini-Zinner...In this manner the stars nearest to Earth might be reached..."

[2] ravityassist.com: The Creation of a new Theory of Space Travel -- Gravity Propelled Space Travel Citat: "...When Minovitch presented it to JPL in the form of 47 page technical paper dated August 23, 1961, it was dismissed by the head of JPL’s Trajectory Group as impossible...How could a young graduate student in mathematics and physics who never studied the problem of space propulsion, space travel or astrodynamics before the summer of 1961 ever invent a completely new theory of space travel..."

[1]

[2]