I read that when the Apollo 11 spacecraft reached the earth's orbit then the engines burnt to initiate TLI(Trans-Lunar Injection) which increased the speed of the spacecraft to 24,500 miles per hour, this happens so the spacecraft overcomes the earth's gravity. When you convert this speed to meter per second then you get 6800 meters per second which means the astronauts were controlling an object that was covering 7 kilometres per second. If this holds then they didn't need three days to travel to the moon. The distance from the earth to the moon is 384, 400 kilometres. If you divide the speed the astronauts were moving at from the Trans-Lunar injection with the distance to the moon's orbit then you get roughly 15 hours to get to the moon. Its also not possible to control an aircraft moving at that speed. How do you defend that?
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2$\begingroup$ Check your math, your calculations are off by a factor of a thousand. $\endgroup$– Nuclear HoagieCommented Aug 8, 2023 at 17:53
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8$\begingroup$ Normal person: "I did some math and it doesn't agree with the numbers on the Moon landing. My math must be wrong." $\endgroup$– Organic MarbleCommented Aug 8, 2023 at 18:15
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2$\begingroup$ Obviously, they took the scenic route! $\endgroup$– FredCommented Aug 9, 2023 at 6:06
1 Answer
If you divide the speed the astronauts were moving at from the Trans-Lunar injection with the distance to the moon's orbit then you get roughly 2288 days
I believe you've confused seconds for hours. 384000 km / 6.8 km/s = 56470 seconds, which is less than a day. The trajectory is not a straight line towards the moon, and slows as the altitude above Earth increases, just like if you throw a ball up into the air, so it takes about three days to meet the moon.
Its also not possible to control an aircraft moving at that speed.
Apollo is not an aircraft. You can't control a car moving at 500 mph, but airplanes routinely fly at such speeds. How do you defend that?
Speed is not really a significant factor in controlling an object moving through space. There's essentially nothing to hit, there's no wind to blow you off course, and the distances are so great that there's plenty of time to make adjustments.
Control of a spacecraft is a cycle of determining where you are and where you're going, comparing that to where you want to be, and making the necessary corrections. For Apollo, ground-based radar stations tracked the spacecraft to determine its position and trajectory, and the spacecraft used either its main engine (for large corrections) or its smaller thrusters to correct its course. The radar tracking was very accurate, and the position of the spacecraft when it entered lunar orbit didn't need to be exact, so Apollo 11 (for example) only needed to make one course correction, about one day into the flight.
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3$\begingroup$ I've edited my answer to explain a little bit about guidance and control. The laws of physics work just fine at seven miles a second. $\endgroup$ Commented Aug 8, 2023 at 18:02
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10$\begingroup$ That said, you are falling prey to the fallacy of argument from incredulity. $\endgroup$ Commented Aug 8, 2023 at 18:21
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4$\begingroup$ @user51882 Oh, did you do the math on that? $\endgroup$ Commented Aug 9, 2023 at 10:21
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6$\begingroup$ @user51882 I'm sure you think you're asking incisive, hard-hitting questions but all everyone else is hearing is "I have absolutely no idea how any of this works, but my ignorance trumps your knowledge so checkmate" and frankly I'm amazed anyone is still taking you seriously. $\endgroup$ Commented Aug 9, 2023 at 17:53
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3$\begingroup$ @user51182 Your core error is that you understand absolutely nothing about orbital mechanics and are thinking in terms of a terrestrial journey. Your assumptions are failing because of all the ways the former is not like the latter. $\endgroup$ Commented Aug 10, 2023 at 16:17