Two Paradoxes of Space Navigation

I will be the first commenter to say I learned something I didn't know. Seems like everybody else is a Rocket Scientist with a degree from KSP :). Henry is the best with his amazing artistic skills and measured melodious delivery.

Finally now know what Hohmann transfer is thanks to this!

I learned this all in KSP

For the first time i knew everything in a minutephysics video Thank you 3700 hours in ksp

500 hrs in ksp makes these "paradoxes" seem not very paradoxical

Back when I was i high school, I learned “East takes you Out, Out takes you West, West takes you In, In takes you East. Port and Starboard bring you back.” Where East means in the direction of orbit, West means retrograde, In means towards Voy (primary), Out means away from Voy, and Port and Starboard are the orthogonals to In and Out. Pretty easy to figure out what to do, once you understand the mnemonic. From Niven’s _The Integral Trees_

Buzz Aldrin’s words of wisdom.

Finally my 1000000 hours of KSP will be useful

WOW! But well explained. Thank you.

1:52 it is important to note that accelerating towards an object in the same orbit and then decelerating once you get there will work if your craft has enough fuel to do it, and this is indeed what spacecraft do to make it the last little bit of distance to link up with each other. It’s just that doing it that way is really inefficient and becomes more inefficient exponentially the weaker your rocket’s thrust is and the farther away you start because you are fighting orbital mechanics the whole time you are trying get there. The reason for the exponentially increasing inefficiency is pretty easy to understand: You are in an orbit and your target is in an orbit and therefore your relative position is constantly changing so the target is always moving away from where you were rocketing towards a second ago, so now you are going the wrong way and have to turn and fight against the momentum going in the wrong direction that you yourself spent fuel to create, so the longer it takes the worse it is. Because we have weak rockets with limited fuel, we always want to take a path that takes advantage of orbital mechanics almost the whole way rather than fighting them the whole way, then only use the simple and obvious method of getting closer for the final docking when the vehicles are already so close to each other that we hardly get any benefit from trying to take advantage of orbital mechanics the rest of the way, and hardly any hinderance from fighting them, so we can use the simple method of pointing towards where we want to go to get it done faster and with more precision. Interestingly, beyond the simplest path and the most efficient path there is also a fastest path, in which you head directly towards a point ahead of the vehicle you are behind of on its orbit such that you arrive there before the other vehicle does. Just enough ahead of it that you can cancel your relative velocity by the time you both get there so you are back on the same orbit and don’t get shot out in a highly elliptical one. The more powerful your rocket or the closer you are to your target, the more the fastest path looks like the simplest path because you have to aim less ahead of the other rocket to get there and slow down in time. The weaker your rocket and the further you are from the target, the more the fastest path looks like the most efficient path, because you have to lead by so much that the place where you need to meet the rocket is on its next orbit and is behind you so you have to propel yourself in the opposite direction if you want to go towards it and thus you will drop into a lower orbit to get there first. Understanding that there is a simplest path, a fastest path, a most efficient path, and the relationship between them I think removes a lot of what is counterintuitive about the most efficient path. Namely that many people think based on how it’s presented that you must do it that way, and that is counterintuitive because it pretty obviously isn’t true if you think about it.

I grew up in the 60's. All we talked about was space and orbits. Breakfast cereal came with cardboard models of the Lunar Lander. These don't seem like paradoxes, they just seem perfectly obvious. Prograde burn at perigee to increase apogee. Prograde burn at apogee to increase perigee. What could be simpler?

I recently started playing ksp again. I see that I'm not alone.

0:30 did you just low-key admit you never played KSP?

Excellent observations, no real paradox though, maybe just anti intuitive, or maybe we just lack intuition in these scenarios.

During the Gemini space program, the first attempt at rendevous with another spacecraft had that problem. They used a lot of thruster fuel and couldn't seem to get closer. It was Buzz Aldrin (yes, the second man on the moon) to right a thesis paper on orbital mechanics to show how you 'thrust away from your target in order to catch up'. Yes, orbital mechanics is... wierd..

Variant of #3 is that I've heard it's easier to leave the solar system than to reach Mercury.

If only there was a game to visualize these

The Anker chargers reboot when you plug in another device, and sometimes they just reboot on their own, which is useless when I got devices connected that don't tollerate power interrupts (like sensors or when I'm soldering with a stereo microscope, and suddenly the ring-light stops working because it's connected to a Anker charger)

I recently watched another video about orbital mechanics that tried to explain the same thing, leaving me none the wiser. You brought it on point in a very understandable manner. Thank you for that!

0:00 I like when I double tap to rewind repeatedly on my mobile phone, I can make a beat