Who was it that discovered that you could use the moons gravity to slingshot around and use that momentum to ?

Question

get back to earth? I'm watching Apollo 13, again, and thats the plan. So is that just your basic Isaac Newton or is it some sort of ...man i have no idea what im talking about...thats obvious.

Answer 1

Its called a gravity assist, gravitational slingshot, or a swing-by, and is used fairly often with space probes.

In 1919, Yuri Kondratyuk suggested that a spacecraft traveling between two planets could be accelerated at the beginning of its trajectory and decelerated at the end of its trajectory by using the gravity of the two planets' moons.

In 1925, Friedrich Zander made a similar argument.

However, neither realized that gravitational assists from planets along a spacecraft’s trajectory could propel a spacecraft and that therefore could greatly reduce the amount the fuel required to travel among the planets.  That discovery was made by Michael Minovitch in 1961.

The gravity assist was first used in 1959 when the Soviet probe Luna 3 photographed the far side of earth's moon. The maneuver relied on research performed at the Department of Applied Mathematics of Steklov Institute.

New Horizons used Jupiter to give it a gravity assist on its way to Pluto.

Messenger did the same with Venus and Earth on its way to Mercury.

Many probes have used this maneuver to speed them up, slow them down, or change their trajectory without using much fuel.

Answer 2

It's been known since Newton that it would be possible.  It was known in his time that the planets moved faster the closer they were to the sun and slingshot around before slowing back down.  This was one of the factors that lead him to his theories on gravity.  The acceleration is simply the energy added to the object from falling into the Moon's gravity.