The Only Video Needed to Understand Orbital Mechanics

** Re-uploaded to fix small errors and improve understandability **

Do you find orbital mechanics too confusing to understand? Well, you wont after this video!

In this Animation we're in space! We are going to look at why when navigating in an orbit, to speed up, you need to slow down your spacecraft! But before we answer that question, we will first review what an orbit is in the first place and what mechanical energy is! So grab a coffee and I really hope you enjoy and learn from my latest work! Thanks for passing by and please consider subscribing for more!!

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Time Stamps:
Intro - 00:00
What is an Orbit 00:31
What is Mechanical Energy 1:13
Different Burns and Their Effects on orbits 2:48
Trying to Navigate in an Orbit 5:30

*Disclaimer* Im well aware that the ISS travels around the earth from west to east, I've animated this in the opposite direction as I felt like the concepts are easier to grasp with a top down clockwise motion of orbits.

Note: The physics and their respective principles throughout this animation are in no way faultless. Theories, speeds, altitudes have been simplified for comprehensibility.

[barnymc]

Love this, KSP really made me understand orbital mechanics

[animationsxplaned]

After a 10 month hiatus to get married, buy real estate and create this animation, I am back! At the time of my last post, there were just over 13, 000 subscribers, and now over 40, 000! 100, 000 subscribers...were coming for you! I'm so grateful to everyone who has watched my videos and patiently waited for the next one! I really hope you all enjoy this one! Cheers!

[magran]

I've wondered about this for 20+ years. Great explanation. You know, this was most of Buzz Aldrin's Ph.D thesis that he never revised.

[starroger]

Great Video and explanation.

So to summarize in a nutshell, and to quote Larry Niven, “Forward is out, out is back, back is in, and in is forward.”

[somedude]

Cool video, great animations! I learned orbital mechanics playing Kerbal Space Program, and I love it so much I'm in college now to become a physicist and hopefully work somewhere like SpaceX. Love that you used the Dragon capsule as your ship!

[photogagog]

Very well done! Have you considered a similar explanation for planetary slingshots? I think a lot of sci-fi writers and even news outlets get it wrong.

[andieeidnaandieeidna]

One suggestion is that towards the end of the video when describing the ISS rendezvous, to start the retrograde burn from the same initial circular orbit starting condition, instead of trying to correct the previous prograde burn. That way, it will be more obvious what the two difference are and how to intercept the ISS.

[sparkelstr]

Kerbal space program players: **I AM 9 PARELLEL UNIVERSES AHEAD OF YOU**

[patricktilton]

The only thing I would change is to show the planet inside the orbital paths rotating about its axis, showing how the suborbital position -- the Earth coordinate -- moves with respect to the orbiting body. Depending on the orbiter's inclination, the North (or South) Pole would be in the center of the spherical planet when the craft is orbiting above the Equator, but would be offset from such a vertical position when the craft is orbiting in an inclined plane relative to the Earth's equatorial plane, with an Ascending Node and a Descending Node associated with this inclined orbital path. Also, depending on the period of the orbit, there would be certain times when the craft would appear above the same point on the Earth below, say, if it orbits 16 times per sidereal day, once every 89 minutes 45.25 seconds. If a spacecraft orbiting above the Equator were to be above 0 deg N, 75 deg W at one point, then after 16 such orbits it would again be above that spot, one sidereal day later. Animating the spinning Earth -- and including a terminator, with a Day side and a Night side -- and having a red wavy line representing the Ground Track as the planet wobbles like a top, now THAT would be cool to see. Maybe a later video could depict these things . . . ? 😎

[Randomguy]

You want to understand orbital mechanics ? Just buy kerbal space program and start playing. At the end you will be a master

[procrastinatinggamer]

At least for orbital mechanics, I think Douglas Adams was right - the trick to flying is throwing yourself at the ground and missing. :D

[jayrussell]

That was pretty EASY to understand...and it IS rocket science. I'm impressed !!!!

[WilliamRWarrenJr]

Thanks! Your explanation is excellent, elegant and accurate! I tend to get technical when I explain it to non-scientific types, but Buzz (he actually changed his name) used to be called "Dr. Rendezvous" because he could figure orbital mechanics in his head, and he is one of my heroes!

[SJR_Media_Group]

*_Former Boeing... your videos are well thought out, easy to understand, even for non-engineers..._*

The ISS loses altitude due to friction with Air Molecules. Even at 250 miles up, some Air Molecules remain. NASA has to change speed and direction of ISS to get it back in it's normal orbit.

*_ISS experiences 90 percent of Earth's Gravity even at 250 miles altitude..._*

[birbeyboop]

I would add that when you do a normal or anti-normal burn, you also add a small bit of prograde velocity to your new orbit at the new inclination, slightly raising your apoapsis

[nicholasspicer]

really helpful if you are struggling to rendezvous while in orbit on KSP, thank you!

[hellorsanjeev]

This channel deserves more subscribers. What an amazing animation. Just subscribed !!!

[giovannicorso]

simple yet effective. One small error: the spacecrafts don't rotate. They would keep the sine direction relatively to space, so they wouldn't be always heading towards their motion direction.

[hupsou]

Just a caution for those looking to understand more carefully. There is a difference between absolute velocity and angular velocity. By doing a prograde thrust to apply force you are increasing the absolute velocity of the craft and decreasing the angular velocity. Another term used in the space industry is "ground trace" that applies here. If you take a straight line from the center of the earth (this gets more complicated as the earth is an oblate spheroid rather than spherical, but that is another topic) to the spacecraft at any given instant the point on the ground (earth's surface) that intersects this line will "appear" to speed up or slow down relative to time. This is a depiction of angular velocity. By increasing the area of the ellipse, the spacecraft must increase absolute velocity, which will expand its total distance from the earth short of escape velocity. In other words, prograde will always increase absolute velocity and decrease angular velocity (even if it does reach escape velocity--i.e. no longer in orbit) and, conversely, retrograde will always decrease absolute velocity and increase angular velocity (up until the point that the orbit remains outside of other physical forces--particulates of atmosphere, space junk, solar winds, and electromagnetic drag, etc.). For reference, geosynchronous and geostationary orbits are much "faster" and "higher" than other orbits, but the angular velocity is nearly zero (it appears to stand still in the sky from the ground. Much higher orbits are still possible, but they will then appear to go "backwards" (negative angular velocity). In other words, the earth's rotation will progress farther than the rotation of the satellite orbit, from an angular or ground observational perspective.

[imagineexp]

Wow, this video is amazing!
Iam in my first year studying physics where we already talked a bit about orbital mechanics but this video is an absolutely gem to get a better understanding of what is really happening…
Thx for the effort, you got my sub!