How did we land back on earth from the moon

927 viewsOtherPlanetary Science

Wouldn’t when we land on the moon, the earth would still be in motion bc of the orbit, and so whenever we exit the orbit of the moon (Which was orbiting the earth) the earth would still be in a constant orbit moving at high speeds, how did we calculate and intercept earth in said orbit.

In: Planetary Science

15 Answers

Anonymous 0 Comments

The movement between the Earth and Moon isn’t that big of a deal.

The Moon orbits around the Earth at the same speed a satellite the same distance from.earth would need to move.

When in orbit around the moon, you just need to move fast enough to reach the moon’s escape velocity. If you escape the moon’s gravity in the direction away from the way the Moon is currently moving, you get your remaining velocity “subtracted” from the speed of your orbit around the Earth.

This makes your closest approach to the Earth (perigee) even closer, so you essentially get to return to Earth for free.

The big issue with returning from the Moon is it is MUCH further away than low Earth orbit, so as you are essentially falling from the Moon back to Earth, you gain a lot of speed, so you either need to use fuel to slow down, or hit the atmosphere even harder than a normal reentry.

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