The Mission that put a Man on the Moon - Apollo Mission

Hi Astronomy Enthuists,
First of all, I want to start out by wishing all of you a very happy and prosperous New Year. In today's blog post, I am going to be exploring the famous mission that put a man on the moon which is, of course, the Apollo Mission. I am going to make this post a little different in that I'm going to explain to you guys the Apollo Mission in-depth, separating the different aspects into bite-sized chunks, making all the info much easier to understand. 

The Apollo Space Mission's Logo

Before we get into the actual Mission, let's talk about the Spacecraft which took the 3 astronauts to the moon and the components of the spacecraft a little.

Saturn V

The Saturn V was the rocket that took the supplies, crew, and everything needed to get to the surface of the moon. The rocket is massive at 363 ft or 110 meters. The Saturn V was split up into 3 stages: S-IC, S-II, SIVB, and the lunar module, Service Module, Command Module, and the Lunch Escape System which is directly attached to the command module and is used for getting the 3 astronauts safely away from the service module if anything goes wrong with the other components of the Saturn V rocket. After everything is good and the Saturn V takes off from the earth, the real deal is yet to come.

Stages of the Path to the Moon

As the spacecraft gains speed, the astronauts in the Saturn V will feel as much as 4 times the gravity as they would feel on the earth. The first stage, or the S-IC, shuts off at 2 minutes and 42 seconds at a height of 42 miles away from the surface of the earth. Right after the first stage shuts off, it separates from the second and falls to the earth. This is also the time when the Launch Escape System is detached from the command module because the rocket is high enough in the altitude that it is no longer needed. Right as the Launch scape System is detached, the second stage or the S-II is activated. The second stage shuts off at an altitude of 109 miles from the surface of the earth at 9 minutes and 12 seconds and then detaches off the SIVB. The SIVB fires for a short period of time to get the astronauts at a parking orbit. For the people who don't know what a parking orbit is, it's called a parking orbit because it's not as high to stay in orbit. To give you an idea of how high that is, the Karman line is generally considered to be the start of space which is about 62 miles above the surface of the earth. And the ISS orbits the earth at an altitude of 249 miles. The third stage shuts off at an altitude of 118 miles at 11.39 minutes but does not detach yet. After orbiting the earth 2 or 3 times, the third stage activates again for about 6 minutes. This is called the Trans-Lunar Injection because this is what sends the spacecraft away from the earth and towards the moon. Now, the SIVB is useless. So, the third stage of the Saturn V disconnects from the Service, and Command Module. But what about the Lunar Module? Since the Lunar Module is attached to the third stage of the Saturn V rocket which is no longer needed, the Command and Service Modules come into action. Just a side note, from now, I will be calling the Lunar Module LM and Command and Service Module CSM when they are combined. So, now the CSM does a complete 180 turn and dock with the LM. Then, the CSM pulls out the LM and continues with their journey to the moon. Here that the important parts of the mission are getting exposed to the extreme heat on the side facing the sun and extreme coolness on the side facing away from the sun, the LM and the CSM implement an idea called Passive Thermal Control which is when the CSM and the LM engaged in a slow roll as they approach the moon.

Moon part of the Mission

Now, let's talk about the actual path or trajectory of the remaining spacecraft. If we were to see the trajectory of the CSM and the LM without the moon, it will look like this: 

Although with the moon, it all comes together:
As you can see, the 2 are still orbiting the earth but in the form of an ellipse. So, if there were something to go wrong with the spacecraft, they will return right back to earth.

As the CSM and the LM orbit the earth, the path of the 2 are altered by the moon because as the spacecraft gets to the spot, the moon comes into play and changed the orbit to this:

Still, if something went wrong with the mission, the crew would come right back to earth. This is called a Free Return Trajectory. If everything is good, the crew enters the lunar orbit. This is called the Lunar Orbit Injection. As the spacecraft is getting into the lunar orbit, the Service Module's engines fire up for about 6 minutes to slow down the CSM and the LM, and unfortunately, this is when they will be on the far side of the moon which is when they will lose contact with mission control in Houston, TX. And this is also where some important things happen. When the astronauts are ready, 2 of the 3 astronauts get into the LM. That's right, only 2 astronauts out of the 3 land on the moon. The other stays in the CSM and continues to orbit the moon. This is when the LM separates from the CSM and starts to descend towards the surface of the moon. How this is done exactly is that the LM has its own propellers. Since the propellers are facing the direction the LM is going in, the propellers in the LM fire up to start their descent to the surface of the moon for about 30 seconds. This is called the Descent Orbit Insertion. Side note: the LM has to get 2 miles away from the CSM to start their descent. Now, the LM is on the surface of the moon, the 2 astronauts set foot, and do science. After being about 50,000 ft above the surface, the engines fire up again for Powered Descent Initiation.

Heading Back Home

Now, it's time to head back home. Just to learn more about the LM, it's split up into 2 stages: the Decent Stage Which got the crew safely to the surface of the moon, and the Ascent Stage. The Decent stage is no longer needed so it will be left but the Ascent stage has its own propulsion system and will be used to carry the 2 astronauts back to the CSM. The propellers in the Ascent stage fire up at the right time and after 3 engine busts or 1 is later missions, the ascent stage on the LM docks with the CSM, and all valuables are transferred to the CSM and the ascent stage is detected and left abandoned in the lunar orbit. But, it doesn't matter because there's nothing left there. This whole process is called Rendezvous and Docking. Now, time to head home for real with all 3 astronauts. This is very similar to what happened before. On the far side of the moon, the CSM fires up for about 2.5 minutes. This is called the Trans Lunar Injection. Now, the crew just has to sit tight until they get to the earth with is about 3 days long. Remember the CSM is the Command and Service Module, you cant actually go inside the Service Module so the crew will have to sit in the tightly packed Command module for the rest of the journey. As we get closer to the earth, the Service module is no longer needed so it's detached. We started the journey with the huge 363 ft Saturn V rocket and we end it with a 10 ft and 11 inches command module. It's finally time for Rentary now. Below the Command module is the Heat Shield which protects the command module as it renters the earth through the atmosphere. After getting about 2 miles above the surface of the earth, the parachutes raise and then, Splashdown. The Mission is over. The 3 finally reached earth after a week of being so far away from home. 

Anyways, that's it for today's blog post. Hope you enjoyed this post and learned something. I had a lot of fun writing and learning about the Apollo mission. Come back for more awesome posts like this one and don't forget to comment on things you liked! Thanks a lot and have a great rest of your day.