The explanations of the moon rotating while always keeping one side facing earth are still perplexing to me, but I hadn’t thought about how fast it’s actually orbiting us. I know the Apollo rockets traveled 24,000 MPH, but how were the astronauts able to safely land the lunar module on a body moving so fast? The lunar module wouldn’t have been able to slowly descend to the surface, it would have to race to catch it. There’s no air resistance to make astronauts or moon dust fly off, but wouldn’t there still be an insane amount of g-force at such high speeds?
In: Physics
Relative speed.
The rockets had to do that speed to leave Earth’s gravity. Once out of it, they could slow down. But what matter is relative speed – relative to the Earth, they would have been going as fast as the Moon. Relative to the Moon, they would hardly be moving at all.
And they slowed *lots* and orbited (I think) before they landed, they didn’t just aim at the Moon at 24000mph.
They launched up, at a point where they were behind the Moon (I believe), they then aim slightly to the side of the Moon, its gravity pulls them round and into an orbit, and they thus use the Moon itself to slow themselves down. Once the speed (actually velocity) relative to the Moon’s orbit / rotation is acceptable, then you can start to descend.
Air resistance plays absolutely not part.
G-Force is how fast you change the speed. So long as you don’t go from 24000mph to nothing instantly, you can do it well within G-forces that you experience on Earth, for example (60mph to nothing in 2.7 seconds is 1g, for example – in half that time is more g). And on launch they went from nothing to 24000mph in a matter of minutes. What makes you think it takes more the other way round?
Speed is a nonsense terms unless it’s relative to something else. Measuring space speeds relative to Earth is dumb. You measure the speed relative to where you are, where you came from, or your destination, depending on which part of the journey you are on. In that respect, the Earth is rotating at over 1000mph, going round the sun at 30 kilometers per second, etc. Those speeds mean nothing, its only the difference between *your* speed and the speed of the thing you’re aiming for that matter. And you can reduce that to virtually zero as you approach them by matching speeds and entering an orbit, so that you can touch down safely.
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