Why Spacecraft Are Using These Crazy Routes To The Moon - Weak Stability and Ballistic Capture. 

I’m an orbital mechanics engineer at ESA and I wouldn’t have explained it better 👏🏼👏🏼

Hitchhikers Guide to Lunar Orbit

This is mathematically and physically beautiful and I cannot imagine the happiness the original scientists felt when putting all of this together

Danuri is Korea’s first lunar satellite! It wasn’t originally planned to do these harder, efficient orbit maneuvers but they kept adding new equipments and sensors to the satellite to a point where they had no options but to take the harder approach. Crazy considering that this is our first spacecraft to the moon. Anyways, huge thanks to Scott for covering space launches and projects from Korea in your videos!

Awesome stuff, n-body physics interactions are fascinating. Have you heard of the Interplanetary Transport Network? It's the concept that all these chaotic interactions create 'pathways' between the Lagrange points of pretty much every body in the solar system. From the Moon to Jupiter, without a single drop of fuel. You'll just need a LOT of patience. (for everything to line up, and for all the natural gravity assists...)

Thinking of the Lagrange points as low effective potential "portals" between Hill spheres is an amazing insight. Thanks for sharing it. I've seen (and derived) the effective potential contour maps many, many times in my life, but never thought of the implications in quite this way. It certainly makes the captures, whether planned or accidental, so much more intuitive.

Did my PhD on ballistic capture, worked with Ed Belbruno at Princeton University, and I'm currently an active researcher on this topic. Yet, I'm always fascinated by this concept as the first days I started studying it.

I really need to try one of these with the Principia mod one of these days. Amazing stuff and the 3D diagram of gravity around the lagrange points really makes everything click into place.

It's kinda crazy that only 50 meters of dV is enough to go past Moon to the edge of Earth's sphere of influence.

I never thought of using Universe Sandbox to reverse engineer orbits like that. Now I have something new to play with. Thanks, Scott. I also am quite surprised that these techniques were developed only very recently.

I remember reading about Bellbruno's work a little over a decade ago. I hunted him down online and emailed him to ask if it was possible to recreate this kind of orbit on the space flight simulator called Orbiter. He actually wrote me back with all kinds of diagrams and explanations. I still haven't been able to totally recreate it on Orbiter but your video helps out a lot. Thanks.

I've struggled to visualize how bodies are captured into orbits without delta-V. Now it's crystal clear. Thank you.

I'd be really interested to hear much mass (as a percentage of the spacecraft's mass) these maneuvers save the craft's designers. Seems like it has to be substantial for the time and effort they spend to perform it successfully! The calculation and risk assessment that must go into it is mind-boggling.

Great stuff Scott. I love your deep-dives in orbital mechanics.

Awesome video. Love the casual solving of a 4-body problem by 2 x 3-bidy problems!

Kudos to your acknowledgment of Ed Bellbruno and his contribution to object deployment in the space environment.

At a high level this makes sense. At a detail level of actual calculations it's a nightmare of instabilities and corrections and changing coordinates between earth, moon and sun. Glad someone else is doing the number crunching.

Seeing that capture tube extend all the way out from the moon was so cool!! It really helped tie the concept together in my head as well. ❤

I know someone who worked on the Lunar Flashlight mission, learning more about it is so cool :O

I took a class this last semester that focused entirely on finding periodic and quasi-periodic orbits and orbital transfers in the circular restricted 3 body problem, as well as extending these results to find solutions in ephemeris models. Fascinating stuff and really cool to see it used in real life!!

I think if you did a video on coordinate transformations, you'd have enough material to just teach a university orbital mechanics course. Certainly better than the one I got...

Every time I read or hear somebody proposing that a planet "captured" a passing body and made it a moon, I think of the delicate - and extremely unlikely - orbital mechanics required to make that possible. You'd need some sort of decelerating collision, at just the right time and place, to act as an "insertion burn". (Anybody think that tidal forces could enable the process, given enough time?)

This is so high level, big respect Mr. Manley!

Who would've thunk that rocket science was this complex

As I watched the video, I wondered if you would get around to giving Ed Belbruno the credit he deserves. I was the Lunar GAS system engineer, Kerry Nock was the project leader, so I saw genius at work. Ed explained the math to me in the hall at JPL. I am still in awe.

Great stuff. I heave a sigh of relief over straightforward mechanical explanations. This is a perfect public level of science. Well done!

To really understand this stuff you need to have some background iin KAM theory (Kolmogorov- Arnold-Moser ) in the context of dynamical systems. Helmut Hofer has done some good Princeton IAS videos on the technical issues in the context of explaining what Ed Belbruno did with the Hiten probe and the concept of ballistic capture. Ed was one of Jurgen Moser's students. Dynamical system stuff is pretty deep - according to Helmut when Ed came up with his idea of saving Hiten many of his colleagues said he was nuts but his ideas worked.

This is a great example on how to do terrific outreach, kudos to Scott. I am a PhD Candidate at Politecnico di Milano, Italy, and at the Deep-space Astrodynamics Research and Technology (DART) group we are currently researching on how to engineer the ballistic capture mechanism for autonomous interplanetary CubeSats with limited onboard resources. We have released in open access on Zenodo a dataset of initial conditions granting temporary capture at Mars in case you are interested!

0:30 What a very sturdy-looking orbit. I don't think a grade 7 pupil could (/would) have done better (/differently.)

Once clearly explained like this, surfing on gravitational forces seems pretty intuitive. I hope KSP2 will have some kind of n-body simulation. That would be so much fun to improvise a last resort trajectory around a L point to prevent Jeb being slingshoted towards the sun. Er. I mean.... that would be so much intellectual satisfaction to carefully plan in advance complex missions using such gravitational tricks. Of course.

The way I think about it is basically a bi-elliptic transfer from LEO to the moon's orbit, but using the Sun's gravity to perform the velocity change at apogee.

I saw many Apollo lunar landing profiles like the one at 0:43 drawn on walls in many cities. Never knew taggers are such space fans.

Thanks for the lowdown, Scott! Hello from Vandenberg Space Force Base!

That is absolutely wild. Blew my mind. The illustrations really do it justice. Thanks for documenting this!

Excellent video! I wondered about the Artemis mission timeline from the moment I first saw it published - since I remember hearing about Sputnik, and remember watching Vanguard 1 fall back and explode on the pad, am an Apollo junkie, and have been in the space game ever since. My very favorite book of any genre is Richard Battin's "An Introduction to the Methods and Mathematics of Astrodynamics", and despite its deep mathematical insights, it contains nothing of this sophistication. Thank you so much for this one, Mr. Manley!

Orbital Mechanics has become much more complex (and cooler) than what I studied in the 1980s!

Love this one. Almost makes me want to play around with this stuff. I do have a question which might also be an idea for one of your videos. With all the variables involved, I imagine that various trajectory adjustments (aka burns) have to be calculated just before they are done in order to deal with actual velocity rather than those calculated before launch. This must especially be the case with these critical paths near Lagrange points. How sensitive are they? How precise do the pointing and burn times have to be? I imagine some missions fail because they get this wrong and fall outside the envelope in which adjustments can be made.

well done. tracking these satellites has required an upscaling of my orbital dynamics and this is a great discussion/explanation hope the flying is going well. RGO

How many objects can we put into the L2 area before they start to affect one another? With the James Webb Telescope already in that area, do orbits need to calculated with that fact in mind. How close did Artemis 1 get to L2?

These types of discussions are WAY outside my pay grade, but I can still appreciate the thought & the amount of computations that it requires. Stay curious!

Fabulous video and explanation! Loved it! Thank you Edward Belbruno

Nice video, but you got a few things wrong. 0:19 Hakuto-R is a landing demonstration programme. The lander is simply called Series 1. The rover is Rashid and is a payload here. 12:00 Hiten is MUSES-A yes, but the smaller satellite is Hagoromo. It's not actually known if Hagoromo made it into orbit because the antennae failed and they were unable to verify its orbit :(. MUSES-B is a radio telescope satellite, not a part of the Hiten mission.

I've been curious about this for my entire life. I never thought it was something I could understand. Thank you so much Scott! You are an amazing teacher.

Using L1 & L2, LaGrange Points for a Ballistic slowdown into lunar orbit is a neat idea. 🚀🌙

So good! Thanks for explaining this beyond-Kerbal idea with such detail and diagrams. Drinking wine at conferences paid off, surely this justifies a bit more?

I listened to everything that you said. all very interesting. I am writing to commend you for your interest and understanding of all things space and for helping us mere mortals grasp the details.

Wow... just as I feel I am starting to make my way up the second mountain, Scott Manley firmly puts me back onto the first mountain of the Dunning-Kruger peaks. Thank you for teaching us these awesome things!

I could never understand how a planet can capture a body and turn it into a moon - if they're arriving they are necessarily in a hyperbolic trajectory (forwards and backward being the same) and should simply fly off. Finally I can see how a capture can happen, especially with the saddle visualisations. Thanks! I still don't know how two galaxies can merge, again hyperbolic trajectories, but maybe that's a future video? :P

the amount of computation required for these lovely dances still blows my mind and the amount of wacky imagination required to conceive these orbits blows my mind out past pluto

Taking advantage of the highly-complex locations where a minute bit of thrust can produce massive differences in trajectory. Simply brilliant.

It’s honestly amazing that at 26 I basically grew up in a world where n-body simulations are trivial. I know about this stuff, but every time I hear about more of the specifics of how this stuff actually works the more it’s incredible anybody not only solved 3+ body problems by hand, but that we figured out how to make computers solve them for us. The more you learn about engineering the more you realize how insanely unbelievably useful computers have been for science. It’s not all about social media lol. The speed of computation allows brute force methods like this. You would spend a million lifetimes solving 10,000 4 body problems by hand, but nasa supercomputers can back date probably a million possibilities in a reasonable amount of time and we have these orbits that basically just would be incomprehensible without computers. We have the knowledge to understand the process without computers, we just don’t have the power to calculate that fast as humans.

I got to see Scott. I always look forward to watching your videos. Awesome stuff. Thanks for all your time and energy. Excellent job.

Wow, Scott, I’ve always had a trouble getting my head around body influences, until you explained langrange points like a topological map and it blew my mind, thank you so much.

Somehow the video title gave me "The 10 Best Lunar Transfer Orbits and Number 8 Might Surprise You" vibes 😄

Beautiful stuff clearly explained, as usual. I remember viewing your material about distant retrograde orbits some time ago. Are there two distinct cases for DROs and for what you present in this video? Does it make sense to compare them? What are the pros and cons of each one?

This was one of the most interesting videos about space exploration i've seen!

In a computational physics undergrad course over 25 years ago, we had an assignment to fire a spaceship from Earth, have it orbit around the moon, and return safely to the earth. If I recall correctly we implemented the Runge-Kutta method which took the 3 body problem and had variable time steps to give the most accurate simulation. I took the assignment way too far, and graphed out the entire space. Given a starting angle (x-axis) and initial velocity (y-axis) what happened to the spacecraft? Impacted the moon? Lost in deep space? Skipped off the earth and ejected? The graph was not simple. I recall one set of initial parameters had a free return trajectory that ridiculously skirted the moon's surface by about 1.5mm, then returned safely to earth. All of this to say that your video has me really curious. All kinds of "bank shots" off those Lagrange points (L1 and L2, both sun and moon) could lead to some fascinating paths with minimal fuel. Would love to see more on this topic. (even if just a recommendation for other videos)

Now I understand why Rich Purnell was a steely eyed missile man. 🤣

This video contains some of the best illustrations and explanations of Lagrange points and orbital mechanics that I’ve ever encountered. Thanks!

0:37 contrary to our intuition, in winter, this length shortens and in summer it grows longer. 😛

having a more efficient trajectory also means less weight contributed for fuel, which means less weight overall, means less payload to orbit, means cheaper launches etcetc, ultimately cascading into more people able to launch smaller, cheaper payloads to the lunar orbit

You really are so good at distilling down complex concepts and serving them up in easily digested bites of information. In other words, you dumb it down real good so that even dodos like me can follow the plot. Kudos! No, seriously, this was a really good video. Make more!

SUPER, frist time I’ve had a explanation that made sense. Nice job.

I don't remember any explanation this intuitive, ever!👍👍👍

This was awesome! I don't think I could do the math, but you explained it perfectly.

Cool, I can't wait to try out 3-Body orbital mechanics in KSP2.

How timely! I started learning in ernest about Lagrange, yesterday. This is a fantastic example! Fly safe. :)

A secondary or tertiary benefit of these long, slow ballistic captures is proving out the reliability of the hardware. I know we have fantastic records of “beyond mission design” longevity in Mars and outer planets missions, but the 2+ years requirements for human Mars missions is better proved (IMO) in the lunar neighborhood.

Great video! Love this kind of content. Very informative and not too computation-intensive!

I’d be worried about making some critical mistake figuring out these weird orbits. I mean, even with the Apollo orbits like 0:37, it looks easy to cock things up.

I heard Scott say "this orbit is perfectly balanced..." and now I'm just imagining a certain RU-vidr at NASA talking about how the orbit is perfectly balanced with no exploits... Joking aside, really interesting and as always, your breaking down complex orbital mechanics into layman's guide is appreciated!

I was disappointed that Scott didn't point out how the "primary" body changed back to Earth for a moment during the final capture. This math is crazy, but with a wonderful result. I'm sure there's a bit of chaos function in the math for those orbits, so tracing it backwards like that probably is the best way to solve it.

i dont want to take anything away from this very great video explaining the complexity and challenges one takes to get to the moon... but that damn first picture.... XD

Would've been nice to hear about this in any of my orbits or GNC classes. Lol. Though maybe I got through before this was much known. Welp. That's why I follow people like you Scott.

Some years ago, perhaps just after the year 2000, I recall reading about the "Interplanetary Super Highway" or "Interplanetary Transport Network", which was all about orbital calculations were now possible that go beyond the classic Hohman transfer orbits.

Bravo, Scott! One of your best explanations.

This stuff is so cool! It's become perhaps my favorite area of space/science. Thank you Scott, we are all lucky you know this so well. Fly safe!

I’m amazed that anyone figured this stuff out.

That's a nice idea to implement in KSP2. Not exactly Principia, but n-body gravity with planets and moons on rails. Only the spacecrafts would be dynamically affected by lagrange points.

This shows how well designed and well organised the universe is, like a giant mechanical clock, only more complicated!

You are a terrific astrophysicist. I hope your employer appreciates you as much as your RU-vid fans.

7:59 there's a tool that NASA (or subcontractors?) used called Deep Space Trajectory Explorer. Might be worth looking into.

Thank you for this video. I have been wanting to better understand how the vehicles get into orbits and transfer to other orbits since the Artemis 1 mission.

Very understandable explanation, thank you, Scott!

This stuff is really interesting and is why Scott Manley rules

This is bananas. I personally want to know how they solved those 3 body problem equations, that’s interesting enough on its own.

My new favorite Scott Manley video. The other favorite video is. WTH is orbital mechanics

Back in the early 1990s while the Strategic Defense Initiative Organization (SDIO) was still in existence, we had designed a lunar orbiter that had a small 2MeV linear accelerator aboard. The spacecraft would be targeted for a 60 km altitude. The proton beam would hit the lunar surface and produce neutrons with energy distribution characteristic of the atoms on the surface. The launch vehicle was the Delta 2. We had Ed Belbruno consult with us on using his weak stability boundary/ballistic capture trajectories since the payload was too heavy for the Delta 2 to fly an Apollo-like trajectory. Alas, there was no interest from either NASA or the Ballistic Missile Defense Organization (BMDO), which was working on its Clementine lunar orbiter, which carried six science instruments for mapping the lunar surface in 1994. Clementine was launched on a Titan II.

This reminds me of similar ways of looking at travel through the solar system I am sure I saw som thing on. Wish I could remember better, but it was something about finding tubes (I guess these would be the manifolds) that allowed efficient travel between planets and then planning missions based on those pathways. So you would basically end up with a roadmap for travel in the solar system. These manifolds would of course change position over time, but now I really wish I could see a 3D manifold map of the solar system evolving over time. That would be so cool!

Universe Sandbox is really amazing! Great video!

Orbital physics hurt my brain at any time of the day.🥵Still, thank you for sharing. Have a great Holiday and stay safe.🙂🙂

Thank you I was wondering why they sent it way out past the moon’s orbit!

As a guy dappling into KSP - these long entry arcs blew my mind.. Imidatly when i saw the animation of it tourning back and then being catched by the moon i was like "damn thats so smart!" Can you do this in Kerbal?

The refinement of orbital mechanics has come along way since Apollo making deep space missions much more accessible to countries and spacecraft that otherwise would be able to participate. We really are in the Renaissance of space travel!

38 seconds in little phallic don't you think? Love your videos Scott 🤣

Wow thanks. I understood the L points but not how to use them. That’s really cool and excellent demonstration.

This reminds me of how in juggling you can take any pattern and time-reverse it to give you a new pattern. The similarities actually makes sense since you're dealing with free-falling bodies in a gravitational field

Scott, excellent work! Very informative for me personally!! Some i's dotted, some t's crossed, so thank you!! 👌 🚀 Fly safe!! 🙏

Wasn't Apollos orbit and route also chosen because if the lunar insertion burn would fail, they'd automatically be returned to earth?