Geostationary, Molniya, Tundra, Polar & Sun Synchronous Orbits Explained

[@michaelpapadopoulos6054]

Scott Manley, you are my favorite bald youtuber and the source of 90% of my orbital mechanics knowledge.

[@--LZ---]

for me it's more like 50/50 kerbal/ Scott...

[@trygveplaustrum4634]

Hey, VSauce! Michael here. Apparently... I've been replaced...

[@hevgamer6087]

and the rest 10% are from KSP or another youtuber?

[@nathanaelvetters2684]

Interesting compliments but good ones for him

[@lawrencedoliveiro9104]

Favourite bald SCOTTISH KZbinr!

[@whatdamath]

I hope the US2 people watch this video and add these simulations to the game. It would be great to explore these.

[@scottmanley]

I’ve been trying to get the unstable Lagrange points to work for more than a single oribit with no luck.... twitter.com/djsnm/status/1083611011267973120?s=21

[@haroldinho9930]

Hello Anton!

[@the_1bane]

Hello wonderful Anton!

[@Peardud]

HI!

[@tybofborg]

Man, I used to think orbital mechanics was complicated. Well I stand corrected. It's even more complicated than I thought.

[@OCinneide]

@Charles Yuditsky I've to know the math, studying astrophysics in college :)

[@GregEwing]

Play Kerbel Space Program and you will find its easy!

[@Enatbyte]

@@GregEwing This is so true. I started playing Kerbal Space Program shortly before going to college to study aerospace engineering. I was surprised by how intuitive orbital mechanics is after you've been messing around with it for awhile in that game. KSP is something I have recommended to all of my friends in the same field. However, I could be wrong, but I don't think KSP accounts for planet oblateness by default, which would make some of the orbits in this video impossible to achieve in the game. I'm sure there is probably a mod for it though.

[@iain3713]

Enatbyte you can get principia for more accurate orbital mechanics

[@Hatchy_Auto_Engineering]

If you get used to the maths it’s actually fairly simple, I’m only in grade 9 and understand orbital mathematics

[@Ludvigvanamadeus]

"just hanging there, in space, in exactly the same way that bricks...don't' I died.

[@unclebrat]

I believe that is a quote from Douglas Adams.

[@patrikhjorth3291]

@@unclebrat It is, from the Hitch-hiker's Guide to the Galaxy.

[@michaelmoorrees3585]

More from the Hitch-Hiker's Guide. The secret to flying. Throw yourself at the ground and miss. That's how satellites work, btw.

[@stephengloor8451]

We just hope they are not Vogons.

[@nathanbrown8680]

And, of course, bricks don't hang in space like that because nobody with the ability to put something in geosync would waste their limited geosync real estate on a brick.

[@AnonymousFreakYT]

I love how the Molniya orbits line up so that with 3 satellites, when one starts dropping, another is *PASSING* it on the way up - makes moving the dish quick. They don't need to slew across a lot of sky to hit the next satellite, just a small change and follow the new one. That minimizes the amount of time there is no service while switching. (I suppose if it's done right, the downtime would be only a second or two.)

[@kazedcat]

The satellite is put exactly in a phase so they line up. You can also put the satellite out off phase so they don't line up but that would be a pointless thing to do.

[@R.Instro]

It's even more effective to have more than one ground station antenna. That way your handover is as easy as flipping a switch to select the new downlink stream. This also allows windows for antenna maintenance during normal operations (ie, windows you don't have to introduce or plan for specially) that you wouldn't otherwise have on a more traditional geosynchronous bird.

[@Wordsmiths]

The Molniya 3-satellite thing is actually very similar to juggling three balls. Of course, when juggling, you try to keep all the balls or bags in the same vertical plane (a single orbital plane, I guess), while a Molniya orbit must put each orbital plane at a 60-degree difference from one another (right? or 120 degrees? help me out...) But the cycling of the three satellites is very similar to the cycling of three juggling balls: slowing to a pause at apogee, the fast classic "scooping throw" at perigee to get the ball headed back toward apogee in an arc that will pass the other two. I'm sure it's exactly the same timing as juggling. And jugglers, like Molniya ground stations, keep their gaze fixed near apogee to "keep their eyes on the balls." (I got all excited when I recognized this similarity! I wonder if one of those Roscosmos orbital mathematicians was familiar with juggling, and adapted it? Or if it's purely a logical mathematical coincidence?)

[@DarkSideChess]

Pretty amazing stuff that the Russians figured out

[@fingmoron]

@@Wordsmiths it's actually very similar to some of the more stylised kinds of juggling too in the crossovers.

[@jerry3790]

I’m very inclined to see what Sun Synchronous orbits are about!

[@kc8omg]

-_-

[@scottmanley]

Assuming you’re in LEO you’re inclined about 98 degrees.

[@nagualdesign]

_Ba-dum bum tssh!_

[@CombraStudios]

pun intended

[@peterbrzezicki8810]

Constant Earth illumination throughout a year. Sensors observing Earth have day and night modes. Sun synchronous orbit gives satellites the same view of the Earth - about 1 h illuminated and 1 hour dark each rotation.

[@PayneMaximus]

How do all those orbits work in a more realistic flat-Earth simulation? ;-)

[@scottmanley]

They don’t

[@PayneMaximus]

@@scottmanley I knew it was all BS about space, the Moon, and beyond! This is clearly another thing that KSP doesn't teach.

[@Ignacio.Romero]

@@PayneMaximus My sarcasm detector is struggling

[@StaK_1980]

How do they work? They... you know... kind of fall flat. ta dumm tssss!

[@Fenrisboulder]

They can't

[@gordonrichardson2972]

At 02:33 should be ISS launches are to the north-east not north-west.

[@scottmanley]

Glad you know what I meant.

[@hansisbrucker813]

I was about to make the same comment

[@gordonrichardson2972]

Scott Manley Another mis-speak at 06:15 should be 23 hours 56 minutes sidereal period of the earth.

[@HangYuriYangFX]

@@gordonrichardson2972 hahaha 23 minutes 56 seconds! He did on purpose

[@RedGreene]

Also shortly before that time stamp he says "Inclination Space Station" XD

[@cosmoscenti5173]

"Just hanging there in space in exactly the same way that bricks don't." sneaky hitchhiker's guide reference, huh?

[@Mylitla]

It's too advanced for this type of introduction to orbits video, but a really cool thing about geosync sats is that they DO appear to move in the sky, albeit ever so slightly. Since EXACTLY zero inclination and eccentricity is impossible to maintain witnout expending a great deal of costly station keeping fuel, spacecraft in these orbits actually drift in a lissajous in the sky. Essentially a 3d figure 8 within a defined orbital "box". The box is small enough that the apparent motion is tiny and of interest only to earth station operators.

[@brianjuelpedersen6389]

This is the type of comment I like: presenting additional useful information I had not ever heard about, even though I like to present myself as and sometimes erroneously pretend to be rather enlightened. Here: Lissajous curves - never heard about them before, but Wikipedia is your friend. I just love to learn new stuff about this wonderful world and universe we all share.

[@R.Instro]

Mylitla Just to be clear, not all such satellites describe a figure 8/lissajou pattern. There are at least some which describe ellipses, which in those cases makes the term "center of box" effectively meaningless. Normally, as you say, the motion is small enough to make active tracking by the ground station unnecessary, but from time to time it's useful to "peak up;" with normal satellites this can be done in one shot at the point where the figure 8 meets at a single central point, but for one which describes an ellipse you have to adjust the antenna azimuth & elevation at different, separate times. Highly inconvenient if one is manually tracking. =D (Eutelsat I'm looking at you for no particular reason, only your birds have the only ephemeris plots I've ever seen where the term "squashed slinky" would be literally appropriate as a description. )

[@IDoNotLikeHandlesOnYT]

@@R.Instro Isn't an ellipse just a very simple Lissajous curve?

[@R.Instro]

Yes, that's correct! However, I'm not as sure that "Slinky (tm) Flattened By Steamroller" qualifies for the Lissajou set of orbits if it's not a repeating pattern. ~_^

[@timstoffel4799]

When geostationary satellites run low on fuel, they sometimes let the figure 8 pattern get bigger and bigger by not trying to aggressively correct for drift from station. They wouls then say these birds were in an 'inclined orbit'. Tracking one of these birds while uplinking to it, without automated equipment was always quite a challenge, and quite a lot of fun.

[@Lady8D]

It never ceases to amaze me how rare it is to find a video with zero dislikes - I'm beginning to think a video that's been up for quite a while with zero dislikes is impossible. Love your videos, thanks!

[@josephblomstrand6348]

This comment aged very poorly lol

[@kkpdk]

Another reason for the GPS orbits being what they are is that the orbital period becomes 11 hours, 58 minutes, ie. twice per rotation. That makes planning the ground segment (which, in normal operation, measures the orbit of each satellite and uploads it to the satellite so receivers can do the calculation) much easier.

[@mattbartley2843]

Yes, what that means is that the satellites' ground tracks are constant. The Molniya and Tundra satellites do the same thing, though because of their eccentricity, their ground tracks are pretty weird. Any geosynchronous (period ~= 1436.07 minutes) or half-geosynchronous (period ~= 718 minutes) orbit will do this. Any satellite in a lower orbit whose orbit is an integer fraction of 1436 minutes will repeat its ground track daily, though with several intermediate tracks during each day. Many Earth observing satellites do this intentionally, including some of (maybe all) of those sun-synchronous satellites. For example, a low orbit satellite can orbit with a period of 95.74 minutes, repeating its track every 16 orbits. Too bad this wasn't mentioned in the video. It's the reason the GPS satellites are at the altitude they are, and an important consideration in many other satellite orbits.

[@tomaspietravallo3832]

I’ve always been waiting for a video like this

[@CombraStudios]

I can hear all the celestial mechanics graduates crying of how they had to imagine the orbits from text, equations and pictures while we the enthusiasts have a brilliant visualisation that teaches weeks of lectures in ten minutes or so

[@aaronmcculloch8326]

Yeah it turns out I've been confusing Tundra and Molnya orbits in casual conversation for a while. Thankfully my cat is too polite to make a big deal about it...

[@dansv1]

Aaron McCulloch I actually chortled.

[@BenjaminBjornsen]

Glad to hear I'm not the only one who talks physics with the cat :p

[@kax5501]

When I worked with part of the Hinode team I couldn't understand how it stayed sun synchronous. Thank you for… illuminating… this concept.

[@oneofmanyparadoxfans5447]

Well played.

[@vladimirlenin4080]

4:08 The Earth around the equator is slightly oblate. *I T I S F A T*

[@Cedillallidec]

Another fat Earth conspiracy theorist.....

[@nagualdesign]

Technically, the whole Earth is slightly oblate, not just the equator.

[@Dutchcomentatah]

ArE yOU fAtShAMiNg tHe PlAneT!?!?!?

[@--LZ---]

#FlatNotFat lol.

[@vladimirlenin4080]

#FatNotFlat lol.

[@pyrusrex2882]

Out of a couple hundred YT channels I'm subscribed to, I spend about 70 percent of my time here on THIS one. Videos like this are exactly why.

[@Poodmund]

6:16 Should probably say 23hr 56m rather than 23m 56s, no?

[@benbaselet2026]

yep

[@marvinkitfox3386]

Its a very *short* day, ok? ;-)

[@El_Grincho]

And about 4.1 seconds.

[@florencegomer7937]

I think a correction caption can be added.

[@AnonymousFreakYT]

He *REALLY* sped up our days... No wonder my hair is standing on end...

[@WilliamRWarrenJr]

Scott Fewkin' Manley, a favorite space enthusiast channel since I found you, you won the "bheer-up-the-nose" award today at 7:11 "Exactly the same way bricks dont ..." I got to meet the gigantic Douglas Adams in Seattle once. But I never got to repeat the blessing. Sad ... We need more Doug Adamses. Adamses (Adamos) are beautiful people.

[@Sugamoto_Magazaki]

I love what an underrated achievement spaceflight is for humanity and what an amazing thing it really is. When you look at how complicated this stuff is and how incredibly amazing it is to be able to say that we've surrounded our planet by our own creations, it's just downright funny to think that every moment someone somewhere is going "Damn this stupid GPS it's taking me through the ghetto again!" xD - Awesome video as always Scott!

[@garytafoya8859]

Right that's crazy 🤣

[@konan4heather]

SCANsat is a great KSP mod that gave me the intuition of orbits - why we need polar orbit to eventually cover the entire surface, etc

[@OCinneide]

Me too

[@TheAechBomb]

I'll be launching an 8-sattelite constellation to maintain contact with my duna base soon, I love the way ksp implements comms

[@lmelin1959]

lol, I like the Douglas Adams quote at 7:10. The guide is still one of the few books that's ever made me burst out laughing in a room all by myself.

[@ReverendTed]

2:16 I've tried so many times without success to conceptualize intuitively why ground tracks look like sine waves, but this visualization made it click. Thanks!

[@a64738]

I still can not understand how it looks like sine waves even after watching this...

[@entropygenerator2646]

Give 15 minutes to Scott Manley and he'll show you the world

[@eleSDSU]

15 minutes, wow, the video felt like 2 minutes long.

[@RodrigoM3llo]

That was what she said

[@Mishkola]

shining, shimmering, splendid.

[@b4nes]

I'm in awe every time i see Scott's like / dislike ratio, It's one of the best on the site. And you deserve it man. For months now your videos are the very first thing I click upon arriving home from work. Second thing I view is Pedws. YEAH. You're that epic!

[@C_B_Hubbs]

This video just went live and it’s just what I wanted right now. Great timing, Scott.

[@AndrewHillis_2024]

BEST EXPLANATION I HAVE SEEN ANYWHERE THAT EXPLAINS ALL THE DIFFERENT ORBITS!!! WELL DONE SCOTT!!!👍👍👍👍👍👍👍

How can you even create these high quality videos so frequently?

[@rogueace9897]

Because he is very manly

[@marioghioneto1275]

Alex Rubey I got that. Lol

[@Arkaid11]

Talent, vast scientific culture, and of course manliness

[@EmyrDerfel]

High-quality camera and microphone and enough computational power to process them quickly.

[@jebediahkerman8245]

This is definitive proof that Scott has secretly mastered time travel.

[@worldsedge4991]

Thanks for the Douglas Adams reference. Ever since I was a kid I thought that “The ships hung in the sky in much the same way bricks don’t...” was one of his cleverest lines.

[@vikkimcdonough6153]

5:22 - It also means your orbit'll decay faster, since you're hitting the (tenuous upper portions of the) atmosphere harder when you and it are going in opposite directions than when you're both going the same direction.

[@Czecher262]

Your content is incredibly interesting. You have knowledge that I cannot comprehend. I normally come to KZbin to watch puppies surfing or dash cam crash videos. Your channel is a refreshing reminder that there are smart people left out there. Keep up the great work and I look forward to you 1 million subscriber moment.

[@bamischijf_2757]

As a kid I watched you because I loved your video's. Now I watch you for help in my studies. Thanks for being a huge inspiration Scot!

[@davidhuber6251]

Outstanding video. I've been trying to teach myself this stuff for decades and you probably doubled my understanding in just one sitting.

[@mikehillier6441]

I remember using a equatorial comm satellites while in Alaska. Almost anything could block our LOS such as parked trucks, carelessly placed equipment and trees. Our RADHAZ area had to be conspicuously marked to keep folks wandering in front of the dish and getting RF exposure.

[@ahaveland]

Excellent visualization software and great presentation aid... Just like to add that I was blown away when I discovered that the ground tracks of GPS satellites look just like the seam of a tennis ball!

[@pratherat]

I got a free trial subscription to SiriusXM with my new car and I live about 48°N. The music cuts out when I'm close on the north side of buildings (shame they wouldn't have a few seconds buffered). My guess is that this is because the signal comes from a geostationary satellite.

[@lmamakos]

All the new radios are using the the XM constellation which are geosync. Some years ago, I had a Sirius radio, and I had better coverage due to the higher elevation about the horizon where I lived, which is in central Pennsylvania where we have hills and mountains and passes. I had a chance to do a direct A/B comparison since my wife's car had an XM radio, and she would have very predicable dropouts due to terrain that I didn't have. And living out in the sticks, no terrestrial repeaters to pick up the slack. This was one of the differentiators between the two services (Sirius and XM) which most people had no clue about.. and now power merger, all the new user equipment is intended for the geosync constellation. Too bad... given the non-steerable antennas on automobiles for that service, the Tundra constellation with spacecraft moving around was a good fit.

[@artyshefartsy]

Amazing video. I am currently studying Orbital Mechanics to get my aerospace engineering degree, and was having a very difficult time understanding and visualizing how these orbits work (my professor is determined to use chalk to draw these out). This made it so much clearer, thank you very much for this amazing educational and fun to watch video!

[@johnholleran]

This is exactly the video I needed!

[@LeethLee1]

AMAZING INFORMATION. IM SORRY I CANT STOP HOLDING MY SHIFT KEY :D Really, your videos, combined with other great math, science and physics channels are increasing my knowledge to a great degree. I'm using it in video game work I'm doing (to fantastic effect), and am aiming for a job possibly at the new mission control in Adelaide, Australia. You give a lot of hope, many thanks.

[@emilartwave]

Another awesome Scott's video. Thanks a lot for explaining hard to understand things! I love this channel

[@LoblollyLights]

omg, I just started up KSP and yesterday I was telling myself I need to read up on the different types of orbits. Talk about a timely video! Cheers!

[@markmcculfor6113]

Can you please do a video about burns that satellites do in low earth orbit to stay in orbit?

[@danieljensen2626]

Probably not that much to say... There is still some gas from the outer edge of the atmosphere in low Earth orbit so things slow down because of drag. Periodically they then have to speed themselves back up.

[@markmcculfor6113]

@@danieljensen2626 yeah, I know, but I would like to hear more about the thrusters that do it at the ISS, and the different ways of doing so

[@PsychoMuffinSDM]

@@danieljensen2626 "Probably not that much to say" And I would have thought the same about rocket exhaust too, but somehow Scott made that interesting. I'm sure he could do the same for satellite and ISS boosters.

[@buffalobillswin187]

I second this request!

[@ahaveland]

@@PsychoMuffinSDM Would be interesting to have more of a handle on the fuel consumption of station keeping and the forces and burn durations involved.

[@KarldorisLambley]

i watched this vid 2 years ago when i become interested in all this sort of thing, and it made sod all sense. however, since then i have made model rockets, learned how electronics work, made model rocket avionics, and then learned how to play kerbal. i just re-watched the vid and it all made perfect sense, there is no finer feeling than that which is caused by the previously incomprehensible becoming understandable. cheers.

[@danieljensen2626]

When you reference another video you should also put the link in the description. I want to watch it after I finish this video, but I don't want to watch all the way through the video a second time just to find the link...

[@danieljensen2626]

@@rangeispow I'm watching on my phone, I rarely use my laptop unless it's work related these days, and I don't think I'm unusual in that. I could open it, then go to history and get back to this video, then at the end go back to history and get to the other one, but that's rather clunky. It used to be the norm to put such links in the description but people seem to get going away from that now for some reason.

[@robinflick5516]

At least ob my phone you can press the button on the top right with an "i". There are the proposed videos listed.

[@PainfulRenegade]

@@robinflick5516 WOW... Great Info, thank you...

[@ryccoh]

just search it after he told you what the title is called

[@PainfulRenegade]

@@ryccoh Holy Moley... that's a hell of a tip!

[@asraharrison]

Wow Scott! This video is a home run. I would love to see you do a long-format video on this subject. There are so many considerations to get maximum usefulness out of any given satellite! It is truly mind blowing! I had no idea that Israel was forced to use retrograde orbits because of geopolitical issues. Everyday Astronaut has had HUGE success with his long-format videos lately, I beg you to consider doing a few of them in the future.... starting with orbital mechanics! 99.9% of the population just wants their smartphone to work, yet they have no idea of the complex science behind getting their Instagram selfie broadcast to the world, or how their digital satellite dish actually works. I want a video that I can share with my muggle friends that explains it in a simple way. I love your style and your delivery, you should be the messenger!

[@MrMarcshair]

HGTTG fan, I see :) Nice educational video!

[@MatthewKelly247]

Thanks so much for clarification on this visually. Makes so much more sense. Please make more of these.

[@crsmith6226]

You have amazing hair

[@jerry3790]

He stole it from Brian May

[@watchfordpilot]

Scott, you answered many of my long standing questions in one go - many thanks.

[@M2M-matt]

Hi Scott could you do video explanation of LeGrange points please and how those kind of orbits work?

[@b.hagedash7973]

Vangelis's - Albedo 0.39 song has always been one of my favourites, it's nice to now understand what at least some of the terms and concepts refer to.

[@aaronncollier96]

6:15 You mean 23 hours, 56 minutes?

[@tiagogobbi3610]

The Molniya it's really like a Ballet, I already see it in a site that track all objects orbiting Earth! Even space trash and maann, are so many objects and satellites that seems Earth have a shield Lol!! Great explanation and very clear as always, Scott! Thank you and fly safe! ;))

[@tomasruzicka9835]

10:40 also the ping is relatively high because of the high distance

[@jannegrey]

"Inclination space station" "1400 an 36 minutes = 23 min 56 sec" Aside from that very informative video. I knew they had to come up with a plan for polar orbits, I just didn't know they were called Molniya (or Tundra) Thanks very much, and don't worry about nitpicks above ;)

[@vikkimcdonough6153]

6:17 - I think you mean 23 _hours_ 56 _minutes,_ not 23 _minutes_ 56 _seconds._

[@robinx1615]

I have waiting a lot for this moment! thanks Scott!

[@jonowack]

This was a good video. I learned something. Well done. Do probes put in the Lagrange points orbit around the L point or do they sit absolutely still? How much real estate is there at the L points? Do we call those objects at the L points satellites?

[@kazedcat]

L1 & L2 is unstable so satellite is put in an orbit that hangs around the L point. L4 & L5 is stable but it is not a point but a region of space that object naturally hangs around. This means that there are plenty of space to place satellites near L points. L1 and L2 needs station keeping to maintain precise orbit. L4 and L5 don't need it objects tend to stay on the region.

[@Pintuuuxo]

Dear Professor Scott, I'm so glad that we don't have to pay for these wonderful lessons!!! Thank you.

[@ppsarrakis]

Whats your though of the radio signals detected from that galaxy?

[@gregparrott]

Very impressive explanation. Other than 'low earth' and geosynchronous, I had not heard of the others, let alone the reasons prompting their existence. Thanks for posting

[@tom_something]

The first time I heard "Sun synchronous orbit" I thought it meant that the satellite would always be in direct sunlight as it orbits Earth. But then I realized the satellite would have to be more than five lunar distances away. So I figured I'd just wait until Scott Manley made a video about it. Thanks!

[@gordonrichardson2972]

There are a lot of different sun-synchronous orbits, the most unusual ones are satellites which need continuous power from their solar cells. This is called the dawn/dusk orbit, as it continuously rides the terminator between day and night.

[@--LZ---]

@@gordonrichardson2972 I feel like you only wrote that out to use "terminator" in a sentence :P

[@gordonrichardson2972]

@LZ Not at all, I was quoting from Wikipedia. Some very interesting orbits: en.wikipedia.org/wiki/Sun-synchronous_orbit#Applications

[@marvinkitfox3386]

" I thought it meant that the satellite would always be in direct sunlight as it orbits Earth" IT CAN BE! If the sunsynch orbit is around the day/night terminator, then the precession from its specific orbit will *always* keep it above the terminator, thus out of the earth's shadow. The only source of shadow would be from solar eclipse by the moon (somewhat common, unfortunately) , or from the sun going out. (rather rare)

[@dirichlettt]

If you want a trajectory that is always in the sunlight, you can try L1

[@Янус_Ырт]

Man, your pronouncion of Molniya is perfect!

[@zapfanzapfan]

So, you're saying that the boy band 98 degrees are actually fans of orbital mechanics? :-)

[@grummhd3020]

or fans of the sun

[@DavidB5501]

Body temperature in Fahrenheit?

[@lersusallarhand5831]

The theory behind the sun syncronous orbit is really amazing.

[@gordonrichardson2972]

There are several different sun-synchronous orbits: en.wikipedia.org/wiki/Sun-synchronous_orbit#Technical_details

[@venil82]

Molniya actually means thunderbolt

[@rasimbot]

No, it means lightning

[@BernardLangham]

actually, "thunderbolt" is an archaic term for... wait for it... lightning.

[@venil82]

@@rasimbot it's the same thing

[@gavinoaw]

That is fascinating, since it sounds very similar to the name of Thor's hammer, Mjölnir, and I think according to legend Thor uses his hammer to cause thunderbolts! Possible that it was brought over as a loanword by the Rus Vikings...

[@OCinneide]

@@gavinoaw Imagine the Rus Vikings whenever there was lightning they'd say something about Mjölnir and eventually it became common to call lightning that. Over time the pronunciation changed to Molniya. If you put it into google translate it actually sounds just like Mjölnir.

[@johnjn14]

Informative and engaging video as always thanks Scott!

[@Gribbo9999]

Talking about positioning systems orbits it's a shame you didn't mention the Japanese satellites that describe figure of 8 orbits from an Earth observer's perspective. This is designed to have the satellites at high elevations over Japan. I understand this is to improve reception in between tall buildings in urban environments. Try as I may I cannot visualise how that works.

[@R.Instro]

These orbits are still geosynchronous, but instead of being circular & uninclined (geostationary) they're inclined so that the northernmost portion of the orbit is over Japan, and elliptical enough that they spend most of their orbit in a useful spot in the sky while still maintaining a 24 hr period. You still need multiple satellites to make this work for constant coverage (as w/Molinya & tundra, etc.) but 4 is enough to make tracking & hand-over demands minimal, at least over the desired target region. There's a recently launched Japanese navigational satellite constellation intended to work alongside (yet independent from) the GPS system that uses this type of orbit as well.

[@Gribbo9999]

@@R.Instro thanks for that. I can usually see several of the Japanese constellation on my phone app.(GPS Status) here in Sydney, Australia. I can see them over Southeast Asia when I travel but not in Africa as you might expect. I still need to see a 3D animation before I can visualise the relative movement of Earth observer and the satellites. - there are some *very* clever scientists and engineers devising these systems.

[@Spaceventuresinvestors]

Thanks for the information about the different orbits. It is a good introduction to the large satellite fleets. Next gerenation satellites that can be refuelled, and the supply-chian to make that happen, are on our radar of possible investments.

[@mal2ksc]

I once almost ended up in a fight with a drunk guy who was convinced that just because you can't see a geostationary satellite from the poles, you can't use satellites up there at all! How dare I assault him with _facts?_ And he was Russian. Sheesh, you'd think he of all people would know about a Molniya orbit.

[@vikkimcdonough6153]

He probably _does_ know about it... when he's sober.

[@suskaklapp6641]

@@vikkimcdonough6153 who's Brian may?

[@jasonmccarthy9764]

Super educational , thank you Scott! Well done.

[@ScottMaday]

5:27 *Israel* : we don’t want to drop our stages for our satellites on our friends going east *US* : have you tried going west?

[@SimonClarkstone]

"friends".

[@CombraStudios]

Excellent video as always. No mistakes and simple explanation

[@niklas6576]

0:25 "... this is the earth and I put a satellite into it." Well, there's some digging involved with that I guess🤔

[@scottmanley]

Fun fact, but the relative density of the atmosphere in low earth orbit vs the ISS is comparable to the relative density of a the crust of the earth and neutron star material. So a chunk of neutronium could orbit inside the earth just fine.

[@niklas6576]

Seems like a good idea! Gimme a sek, I'm going to call Elon, he'll know how to make it happen😂 Now, seriously... I really like your combination of knowledge and wit, that makes your video really enjoyable! Keep it up and maybe, just maybe, someday they will name the subsurface neutron star orbit after you😂

[@joemiskell4849]

Another awesome vid Scott! Always learning things on here I didn’t know I didn’t know

[@chrismusix5669]

Israel's always having to do it the hard way!

[@gavrifalcao]

They also don't use to anounce when they're gonna launch something. Once I was in Ashdod doing my everyday stuff and simply the sound of the Shavit came loud. At first people though it was the defense system, but when the second stage kicked in, we realised it was the Shavit launching Ofek 11.

[@asraharrison]

Yep, I wonder why they can't build a launch facility on Diego Garcia or some other NATO/US held island or territory. It seems that launching from Israel is a real PITA... something I had never even considered before.

[@cmpe43]

Both my brother's are rocket scientists and I quit College to become a Pit Trader, I made the money but this is way more fascinating than making the donuts so thanks for educating us!

[@Lezzylree]

Who else is eating while watching this?!

[@--LZ---]

Who else is alive while watching this?!

[@Lezzylree]

@@--LZ--- I know right!!!

[@archenema6792]

They let me have this instead of food.

[@nikmathews555]

Awesome video, I’ve been curious about how these all work. I didn’t get sun-synchronous orbits at all until you explained them. Cool to see how to deal with communications at high latitudes as well (molniya) 👍👏

[@chris-hayes]

Fantastic explanations! I've never quite understood all the different orbits.

[@datalorian]

Great video, Scott. I had no idea you could do that sort of simulation in Universe Sandbox².

[@vijeykrishnaa2230]

Very interesting... I've been looking to learn about different types of orbits for a long time now! Thanks!

[@jeffk1482]

Always good stuff Scott! Have to say I laughed hard at the Vogon spacecraft reference about 7 or so minutes in!!! 🤣

[@bradley772]

Once again... thanks so much. Great information.

[@sapphiretownsend7329]

I can't believe I found the channel one day before my spaceflight exam :( Things I see an animation for I remember so much better

[@rosswarren436]

Wow, I didn't even know Universal Sandbox existed. Way back when there used to be a software program you could get called Satellite Tool Kit, but this is even easier to use with far better graphical representation. Cool. Thanks for showing it to us!

[@CavemanToaster]

@Scott Manley. Can a tidally locked planet have a sun-synchronous orbit?

[@deusexaethera]

...okay, whoever came up with the self-adjusting Sun-Synchronous Orbit is a freaking genius. I never would've thought of that.

[@lostpony4885]

I keep hearing about sun synchronous orbit. I really need this vid Scott thx

[@scottmanley]

Search for ‘fat earth theory’

[@mastur_grunt4244]

Excellent video Scott!

[@PaulNewfield-PasadenaCAU-wb4xg]

@ 6:05, when showing the geostationary orbit, do the orbit in retrograde where the satellite travels west around the equator, only increase the altitude slightly so the satellites period is 24 hours. If the satellite is launched at noon the satellite 🛰 will pass overhead the next day at noon, 24 hours later! THE SATELLITE 🛰 WILL BE DIRECTLY BENEATH THE SUN ☀️ FOR THE ENTIRE ORBIT! How could this be possible unless the Sun ☀️ was also orbiting the earth 🌍? Launch the satellite 🛰 at midnight, and the opposite will occur, the satellite 🛰 will pass overhead every night @ 12 and would never see the daylight side of the earth! The only way this is possible is for the earth 🌍 to be motionless, & the Sun☀️ AND satellite 🛰 BOTH ORBITING THE EARTH 🌍 EVERY 24 HOURS!

[@foximacentauri7891]

I've seen you doing so many cool things with universe sandbox and kerbal space program, I should probably buy them myself.

[@ToddDrew-h1j]

Hi Scott! I really, really enjoy your fine videos! Great work! I watched the “orbital classes” this morning and it made me think again about the growing problem of clutter in orbits from useful satellites AND debris….. have you done a video on this subject? If not, how about doing one?!

[@skyrien]

Most interesting things I learned something today came from this video. Thank you for sharing knowledge in the appropriately accessible level for space enthusiasts!

[@Obinjess]

It's fun to watch the Molniyas when they are at perigee. You can see them easily with binoculars and sometimes even the naked eye. They haul ass across the sky and you could mistake one for a jet at high altitude. They're really moving FAST on their way back up to apogee.

[@justanotherperson2960]

Another great thing with gnss or gps orbits in this case, is it's almost perfect ground track repeatability. The inclination and the almost nil eccentricity combined with the Oblateness of Earth having very low secular resonance with this orbit, allows for perfect ground track. This helps with almost perfect estimation of position while tracking. Edit: perfect tracking is required to prevent errors in satellite ephemeris during trilateration of your position.

[@engr.nemuelobas4923]

Ive been always waiting this topic for a long time. Thanks

[@qswat7268]

This is one of my all time favorite videos!

[@PowerScissor]

@12:40 he mentions signal intelligence satellites. I downloaded the SIGINT declassified documents, but they are terrible quality photocopy pdf files, almost 500 pages, and redacted pretty significantly. Does anyone know a good source for a summary of those programs?

[@buffalobillswin187]

This is a great example. Thanks. I'll save this to explain to a couple people.

[@arnoldgaarde7066]

Mann you are such a great explainer Thank you for all your informative work