I don't know the exact numbers. but on the way home they did no have to lift a massive rocket against Earth's gravity. I imagine that helped a lot (most of the fuel was probably used to lift the other fuel).

One question per post, please. Please do some prior research too. The answer to your #3, for example, is obvious.

New here. I apologize for multiple questions but they are all related to re-entry. No one has answer any of these questions yet. And if #3 is obvious... share the answer. Of course I did research and found nothing. THAT's why I'm here.

I would write a full proper answer, but the question has been closed. In the future, try asking 1 question per question. Then it will probably not be closed so quickly.

@LARick question 1, almost no fuel was needed because they only needed a bit for course correction, the rest was freefall. Question 2 they had fuel tanks which contained the Cryogenic Oxygen and hydrogen. Question 3, because the Service Module did not have a heat shield and the Command Module did. Question 4, during lift off the Saturn V accelerated them to that speed. When they returned, the gravity of Earth accelerated them to that speed. They also reentry Earth at around 25 mph.

Thanks Rocket fan! I'd like to followup with a deeper dive into your answers. My email is [email protected]. Not sure how else to converse without agitating the forum folks.. 🤷🏽‍♂️

@TheRocketfan After reading again.. your #1 and #4 answers are DEEPLY flawed.

@LARick given the information from The Rocket Fan and your research the next step is to edit your post so it can be re-opened. The issue as is that the stack exchange structure includes you selecting a 'correct' answer from the responses and with four largely unrelated questions that is not really possible. Given your interaction here it looks like you have two perfectly valid and answerable questions about fuel to come home, and arrival velocity, one of which can be edited here, and the other spun into a new question.

I voted to reopen the question, but @LARick I am not so sure why you think that my response to question 1 & 4 were deeply flawed. For question 1, the moon‘s gravity has only 1/6 the strength of Earth’s gravity. So one would think that you would need a rocket that is only a sixth of the size. However, lots of the fuel in the Saturn V was used to lift the remaining fuel up. This is the case for all rockets and cause their size to grow proportionally bigger. See this for more info: space.stackexchange.com/a/17576/44505 So in 1/6 gravity you would need a much much smaller rocket.

Question 4, The speed to re-enter Earth's atmosphere varies depending on the specific re-entry trajectory, but it typically ranges from 17,000 to 25,000 miles per hour (27,000 to 40,000 kilometers per hour). The conical module, such as a spacecraft or capsule, reaches this speed by using the gravitational pull of Earth during descent, combined with its own propulsion systems, if available, to adjust the trajectory and control the re-entry speed. Here is an animation: en.m.wikipedia.org/wiki/…

Be aware that the animation only shows a spacecraft going to the moon and not returning.

LA Rick - I think the reason @The Rocket fan's answers for #1 and #4 may seem flawed is because we are limited to 600 characters in the comments so not much room for more detailed explanations. #1 to throw a rock high up in the air requires a bit of energy. But it takes no additional energy for the rock to be pulled back to Earth. The energy you invest when you throw the rock up is reclaimed as gravity pulls it back down at a similar velocity. In the same way it took a huge amount of fuel to "throw" the Apollo capsule to the Moon, but essentially no energy was needed to fall back to Earth.

LA Rick - what @The Rocket left out regarding #1 because of comment length limits is that when the Apollo capsule reached the Moon it had to use some fuel to go into lunar orbit. To return home they had to use some fuel to undo this and break free of lunar orbit. This allowed Earth's gravity to begin pulling the capsule back to Earth, accelerating it the entire time. For #4 I'm not sure what the concern is, other than they left off the "k" in 25 k miles per hour. Apollo 11 burned fuel to accelerate to 24,236 mph on the way to the Moon, they reentered Earth's atmosphere travelling 24,735 mph.

I greatly appreciate the additional info!

I greatly appreciate the additional info! But, Earth's gravity would NOT play a role on speed UNTIL the command module has passed through the outer edge and into our atmosphere. Even then, objects fall at a set speed. Also, the majority of the inner-atmosphere descent was after the parachutes deployed. Fact is, the Command module had to travel ~225,000 miles with VERY little room to store fuel.

Regarding the Command Module not burning, but the Service Module burning.. on re-entry... Um... They both passed through to space on the way out.. and if the service module did NOT have the "protective coating" then.. you guessed it.. can't have it both ways. Lastly, aerodynamically, the conical module ain't reaching speeds of 25,000 mph .. let's be real. Anyway, I love this kinda of stuff, but I have serious and common sensical questions about a lot of things we are told. Thanks guys!

@LARick I am happy that you have taken an interest in space exploration and also this site. However, you have some misunderstandings about some things which I would be happy to explain, but it is really difficult to do so in the comments. I really recommend asking those questions individually so that each one can be throughly answered.

LA Rick, your statement "the conical module ain't reaching speeds of 25,000 mph .. let's be real" implies that you believe that the Moon landings were faked. Perhaps that is not what you meant. It will help if you clarify your position on the Moon landings, and also explain why you think that the Command Module was not capable of reaching speeds of 25,000 mph.

Hey Steve! Fair question. I am firmly planted in mid air. I see as many arguments against, as I do for. So, I do as much research as I can to fill in the blanks. But I must say, most answers to tough questions are very vague, assumptive, and spoken as if fact when not really challenged or proven.

@LARick if you click on the blue button „ask question“ and then ask each question there individually, then I could give you an answer that would explain things in detail with proper sources. It is not easy to do so with comments and this closed question probably will not be reopened.

will do when free - thanks again, Rocket Fan!!!