Space Travel

( Figure 1 : Two Astronauts out of the Lunar Module and Exploring surface of the Moon)

Galileo measured gravity’s strength but couldn’t explain it any further. Newton interpreted gravity as a force and wrote down the theory of gravity in its mathematical form.  Einstein saw gravity differently. Einstein linked gravity with the geometry of space-time and that is the most accurate theory of gravity till date.

Gravity is neither a boon nor curse to humankind. We are used to it. You fall from height and injure yourself but without gravity there wouldn’t be any rivers nor valleys. Sometimes Gravity make you fall in love. You see that when someone madly in love threatens to jump off a building. Gravity causes tides which enables surfers to show their moves. Gravity is omnipotent and it is impossible to write down about all the things that Gravity is capable of.

However, I would like to share how far humans have ventured in  quest of conquering the Gravity. Here, we would see how NASA’s Apollo mission made it to the moon.

(Figure 2 : Saturn V Rocket on the Launch pad)

On earth, we have flying machine with wings. An airplane has engines which provides thrust which propels the aircraft forward whereas wings generate lift and keeps the aircraft in air. How about outer space? Where there is no air. Wings won’t help us and a jet engine will be dead without air. That is when rocket fuel comes in to equation. Liquid hydrogen and oxygen are used along with other chemicals to form rocket fuel and the best part, it doesn’t need air for burning.

We have got rocket fuel, what else do we need?  We need a rocket engine. Rocket engines work by burning fuel and generating thrust in a direction opposite to the rocket’s motion.  We then attach payload to the rocket engine and we are ready for the launch.

But before that we need to know what payload contains. It consists of a Command and Service Module (CSM) and a Lunar module. CSM carries crew(astronauts). Its role is to stay in moon’s orbit and retrieve the Lunar module and get back to earth. Lunar module is the spacecraft which will land on the moon’s surface with a couple of astronauts.

(Figure 3: Saturn V Rocket Stages)

Now with Rocket fuel, Rocket engines and all the payload, what are we waiting for??  But before the rocket lifts off, I will bombard you with another  very important information. These rockets doesn’t come in single piece . It has stages(see figure 3) . Saturn V rocket which NASA used for the Apollo mission had three major stages as shown in the figure. The whole purpose of separating a rocket into stages is to lower the amount of mass being propelled as the rocket gets higher and higher . By doing this, rockets are able to carry more payload which would not have been possible otherwise.

Now it’s time, we lift off. The countdown begins. Fuel starts burning and slowly the Saturn V rockets starts accelerating upward from the launch pad (see figure 4). The first stage of rocket gets on work at this moment .

(Figure 4: Saturn V taking off)

The first stage of the rocket burns for about 168 seconds and propels the Apollo spaceship about 67 km above the surface of the earth at a speed of 2300 m/s .

(Figure 5: First stage propelling Saturn V up high )

The first stage is used up and then separated . Its of no use so now.  It falls in to the Atlantic Ocean.

(Figure 6: First Stage getting separated)

we are now left with the second and third stage of the rocket plus the Apollo spaceship (see figure 7).

(Figure 7: Second stage ignition )

The second stage fires up and for approximately  6 minutes and gets separated (see figure 8).

(Figure 8: Second Stage separation)

Now the third stage ignites (see figure 9 ) and takes Apollo spaceship on course to insert it into the earth’s orbit .

(Figure 9 : Third stage ignition )

Rockets needs to gather approximately a speed of 7 km/s to get itself in the low earth orbit before making a Trans Lunar Injection (TLI).  Don’t panic!! We will get a good idea of what a Trans Lunar Injection (TLI) is(see figure 10). The third stage of the rocket delivers necessary push to get spaceship speeding at the required speed . Now the the spaceship along with rocket’s third stage is at about 191 km above the surface of the earth and orbiting.

(Figure 10 : Trans Lunar Injection (TLI) and the trajectory towards the Moon)

After the rocket makes it to the earth’s orbit, the spacecraft needs to make its course towards the moon. The process of maneuvering spacecraft’s on a trajectory that will make it arrive at the moon is called a Trans Lunar Injection (TLI).  This process lasts for approximately 6 minutes. The third stage of the engine burns and propels the spacecraft to near earth’s escape velocity (i.e. 11 km/s). The aircraft is now on its way to the moon(see figure 11).

(Figure 11: Spaceship on its course to the moon after TLI)

After the completion of TLI, the third stage of the engine is separated from the spacecraft . First, the Command and Service module gets separated from the third stage (see figure 12).

(Figure 12: Command and Service Module(CSM) Separation )

Now it’s the time we extract Lunar Module  from the rocket’s protective case. The panels covering the Lunar Module gets jettisoned out exposing the Lunar Module (see figure 13 ).

(Figure 13:  Four panels protecting the  Lunar Module being jettisoned)

The Command and Service Module(CSM) then  turns 180 degree and extracts the Lunar Module from the rocket’s body(figure 14).

(Figure 14: Command and Service Module(CSM) turning around, docking and then extracting the Lunar Module )


(Figure 15 : The CSM and the Lunar Module on their way towards the moon)

Now all what remains is Command and Service Module (CSV) and the Lunar Module, drifting in empty space towards the moon(see Figure 15). It is going to take more than 2 days to reach the moon. When the spacecraft nears the moon it performs another maneuver to get itself in the moon’s orbit ( Show in figure no. 16 as dotted line).

(Figure 16 : dotted line is the course taken by the spacecraft to get into the moon’s orbit)

(Figure 17: The spacecraft in making it into the moon’s orbit)

The spacecraft makes to the moon’s orbit(figure 17) and now comes the fun part . There are three crew members in the Command and Service Module (CSV). Two of the crew member transfer into the Lunar Module. One remains in the CSV. The Lunar Module is detached from the CSV and prepares to land on the Moon’s surface(see figure 18).

(Figure 18 : Lunar Module detachment from the CSM)

The Lunar Module performs engine burning maneuvers(see figure 19 & 20) and lands itself on the Moon’s Surface all while the CSV keeps orbiting the moon(See figure 21).

(Figure 19 : Lunar Module performing engine burning maneuvers )

(Figure 20: Lunar Module maneuvering to land on the Moon’s surface)


(Figure 21 : CSM keeps orbiting the Moon while Lunar Module is on the verge of landing on the Moon’s surface)

Hip Hip Hurray!! Congratulation. We have landed on the moon (See figure 22)

(Figure 22: Lunar Module lands on the Surface of the Moon)

What good a Lunar mission is if you do not step on it’s surface. As mentioned earlier the Lunar Module carried two astronauts in it. The First Apollo manned mission, i.e Apollo 11 had three astronauts on board the spaceship . They were Neil Armstrong, Buzz Aldrin and Michael Collins. Neil Armstrong and Buzz Aldrin were given the task of getting Lunar Module to surface of the Moon and step on the Moon’s surface . Michael Collins, on the other hand was tasked with holding the Command and Service Module into the orbit of the Moon .

All of the Apollo missions were quite the same with two astronauts making it to the surface of the moon(see figure 23) and one remaining in the CSM . The astronauts on the Moon’s surface collect some samples of the moon rock and soil and installs some scientific instruments. Not to forget they also perform “The Moon Walk”.

(Figure 23 : Two Astronauts out of the Lunar Module and Exploring surface of the Moon)

However, the job is still far from finished. We need to get back to the earth.  The Lunar Module has an Ascent stage which is fired up to get the two astronauts back into the moon’s orbit (see figure 24).

(Figure 24: Ascent stage of Lunar Module firing up)

When in the moon’s orbit the Ascent stage of Lunar Module rendezvous with the Command and Service Module (CSV) (See figure 25, 26 & 27).

(Figure 25 : Ascent Stage of Lunar Module getting into same orbit as that of CSV )

(Figure 26: Ascent stage of Lunar Module and CSM starts to rendezvousing )

(Figure 27 : Ascent stage of Lunar Module and CSM rendezvous completion )

After the rendezvous, the two astronauts from the Ascent stage of the Lunar module  gets transferred to the CSM . Now it’s time to ditch the Ascent stage of the Lunar Module as it is of no use to the crew. The Ascent stage of Lunar Module is separated from the Command and Service module(CSM) . (See figure 28)

(Figure 28: Ascent stage of the Lunar Module separation and preparation to head back home)

Now its time to head back home. The spacecraft performs Trans Earth Injection, the maneuver to align itself along the trajectory towards the earth (figure 29).

(Figure 29 : Spacecraft performing Trans Earth Injection)

It takes more than 2 days to return to the earth’s surface. Before the spacecraft lands on the Earth’s surface , it maneuvers itself to get into the Earth’s orbit (see figure 30).

(Figure 30 : Spacecraft getting into Earth’s influence)

Now before the final descend , the Service module of the Spacecraft is separated and the conical shaped Command module is all left with three astronauts inside which lands on the surface of the Earth(see figure 31). The atmospheric drag causes friction which generates enormous heat . This heat engulfs the service module and it looks as if a fireball is falling from the sky. The outer coating of the Command module is such that it can withstand this high temperature.

(Figure 31: The Command module with three astronauts inside performing re-entry into the Earth’s atmosphere )

In order to slow down the Command module, parachutes are deployed and finally it lands on the Earth’s surface(see figure 32). During Apollo mission these Command modules were made to splash down in the Atlantic Ocean.

(Figure 32 : The command module deploying parachute to slow down before the landing)

The landing spot is  predetermined and astronauts are retrieved from the vessel .

This was a very rough picture of how Apollo mission made it to the moon and got back home safely. Lots of technical details are skipped here but I think one can get a fair idea of how it was done. It’s been more than 50 years since  humankind first landed on the Moon but little progress has been done to explore other heavenly bodies with humans on board after that. All of the manned space mission of today have only been to low earth orbit  . With new space enthusiast , we are hopeful for the future space travel . As far as we know, Mars is going to be our next destination. I strongly believe space travel is going to create a huge buzz in immediate future .

Therefore, If you happen to make a rocket powerful than Saturn V and a spaceship in your garage , please let me know. I will volunteer to go to Mars.





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Surya Kiran Yadav

I write on Physics, Space Travel and military technologies
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Last modified: September 9, 2019

10 Responses to :

  1. Prakriti says:

    The way you explain things is awesome.. Student from any subject can understand it..

    1. Surya Kiran Yadav says:

      Thanks a lot Prakriti. That is going to get me write more. 🙂

    2. Nishant Khidtta says:


      1. Surya Kiran Yadav says:

        Thanks Nishant . I hope you are still singing songs . 🙂

  2. Shyam says:

    It’s the pictorial description with soft twining words. It is fist time study astronomy looking so interesting. Thanks you for hard work and Keep it up.

    1. Surya Kiran Yadav says:

      Thank you Shyam ji. Your words are encouraging. We will try to keep this going and improve wherever necessary .

  3. Loved your presentation and insights. The contents are precise, illustrative and moreover even minor details are stated really well. Good job dai.

    1. Surya Kiran Yadav says:

      Thanks a lot Abhisek.

  4. Yuwaraj Adhikari says:

    Awesome. I was just travelling to moon while reading this Article. Kudos to Surya.

    1. Surya Kiran Yadav says:

      Thank you Yuwaraj and if you have reached moon please stay there . Earth is a terrible place 🙂

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