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

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

Play Kerbel Space Program and you will find its easy!

@@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.

Enatbyte you can get principia for more accurate orbital mechanics

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

I believe that is a quote from Douglas Adams.

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

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

We just hope they are not Vogons.

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.

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

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

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

Interesting compliments but good ones for him

Favourite bald SCOTTISH RU-vidr!

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

Hello Anton!

Hello wonderful Anton!

HI!

-_-

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

_Ba-dum bum tssh!_

pun intended

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.

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.

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.

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?)

Pretty amazing stuff that the Russians figured out

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

They don’t

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

@@PayneMaximus My sarcasm detector is struggling

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

They can't

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.

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. )

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

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. ~_^

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.

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.

Another fat Earth conspiracy theorist.....

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

ArE yOU fAtShAMiNg tHe PlAneT!?!?!?

#FlatNotFat lol.

#FatNotFlat lol.

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

That was what she said

shining, shimmering, splendid.

Right that's crazy 🤣

Well played.

Glad you know what I meant.

I was about to make the same comment

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

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

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

This comment aged very poorly lol

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

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...

Aaron McCulloch I actually chortled.

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

Me too

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

yep

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

And about 4.1 seconds.

I think a correction caption can be added.

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

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

Because he is very manly

Alex Rubey I got that. Lol

Talent, vast scientific culture, and of course manliness

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

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

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.

He stole it from Brian May

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.

@@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

@@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.

I second this request!

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

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.

@@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.

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

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

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

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

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.

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

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

" 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)

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

or fans of the sun

Body temperature in Fahrenheit?

No, it means lightning

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

@@rasimbot it's the same thing

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...

@@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.

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

@@vikkimcdonough6153 who's Brian may?

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.

@@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.

"friends".

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.

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😂

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.

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.

Who else is alive while watching this?!

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

They let me have this instead of food.