“It’s not Rocket Science.” This is a phrase that many of us have used at least once our life to say that you do not think that something is very difficult to do or to understand.

Let's put the notes down. A Rocket (space transportation, launch vehicle) is a “thing” that “spits out” hot gasses, a simple yet forceful machine that propel objects into the air.



Some sort of chemical reaction occurs in closed or sealed volume (tank) that causes the escape of a gas with a high speed. Similar to a balloon!!! 


For every action there is an equal but opposite reaction

Newton’s Third Law


Skin of the balloon is stretched tight, squeezing the air inside so it has a high pressure than than the air in the room. To equalise this pressure, the air is forced out the stem and following Newton’s 3rd law, the air is forced out (action) and an equal force pushes the balloon in the opposite direction (the reaction). Balloon flies wildly because its unstable!!! Finally, with some form of ‘control’ like adding fins we can have a small rocket!


Consider yourself sitting on a wagon armed with a bag of tomatoes aiming to me (NOT). If you are at rest and begin to throw tomatoes to me because of Newton’s 3rd law an equal but opposite force will move you (and the wagon and tomatoes) in the other direction.


Now you had to use some force to throw the tomatoes, the force moving you on the wagon is identical in magnitude but opposite in direction. From the concept of conservation of linear momentum: Change of speed of tomato (because its small) will be greater than the change in speed of the wagon.




This is how a rocket works: it expands energy to eject mass out the back at high speeds, pushing the rocket in the opposite direction. Mass is being ejected at a rate we refer to as mass flow rate:


Δm / Δt = ṁ (kg/s)


A rocket engine has three basic parts: combustion chamber, a throat and a nozzle!



It’s not that hard! In future articles and courses you will be able to learn in more and more about Rockets. GEO University opens new learning Horizons.

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Written by

Mr. Fotias is a Space Expert and Satellite Remote Sensing Specialist with specialty in Radar Remote Sensing (SAR). He graduated as a MEng in Informatics and Telecommunications Engineer in 2012, and MSc in Space Technology and Planetary Exploration in 2014 from University of Surrey. From his graduation till today he has work for several private and public entities related to Space, E/O and GNSS applications, participating in more than 15 RTD funded Projects. He currently works as a Project Manager in Worldwide, European R&D and Commercial Industry Projects. He is a motivated, enthusiast and results-oriented professional in Satellite Remote Sensing (high level of technical competence and ability in SAR theory, applications and general image) with expertise in radar processing algorithms. He has more than 5 years experience in geospatial and remote sensing analysis. Well versed in quantitative analytical research, particularly with ESRI ArcGIS suite and ENVI. Expertise in advanced satellite imaging processing, interpretation, land cover mapping, agriculture applications, time-series analysis, and land use and land cover change (LULC) analysis. He is also involved in managing a dynamic portfolio of Technological Innovation projects

Vasilis Fotias

Space Expert | Remote Sensing Specialist

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