Wikipedia writes to say

Once the spacecraft reached the far side of the Moon, its rocket motor was fired in order for it to be captured by the Moon's gravity into an elliptical lunar orbit.[27]

I vaguely recall reading the Apollo 11, and Apollo 13 slowed in the shadow of Luna, or just shy of the far side.

Is LOI (lunar orbit insertion) usually performed on/close to the far side of Luna? Why?


Typically yes. Basically, it provides the best delta V to achieve an orbit. Let's see if I can sketch a picture of each case.

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Okay, so what are the relative advantages of each? The first is closer to an actual orbit around the Moon. A short burn will lower the apogee of the moon such that it will be orbiting well. The second case is quite a bit more work. I'm struggling to fully understand what will happen, but basically you'd have to increase your speed somehow, and it's much less natural and thus would probably take more fuel than the alternative.

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  • $\begingroup$ A corner case - low-energy transfer (via Lagrange points) does not necessitate LOI on the far side. Which may be convenient for tracking. $\endgroup$ – Deer Hunter Sep 13 '13 at 6:22
  • $\begingroup$ @DeerHunter: True, but that would add some time. Rocket thrusts, especially big ones, are almost always automatic, it really just doesn't matter if it's done in view of the Earth, and time is more important than a bit more info. $\endgroup$ – PearsonArtPhoto Sep 14 '13 at 1:18

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