There are 10,341 satellites
orbiting right above our heads.
One is the moon, but the rest were put there,
and in some pretty interesting orbital configurations.
In this episode, I'm serving up a tier list of my favorites,
starting from the edge of space and working our way up.
Who knows, along the way, you might even learn
some interesting orbital mechanics.
But what is an orbit?
You can imagine spacetime like a giant trampoline.
Or in this case a small trampoline,
'cause I spent all my money on coffee.
Massive objects like this pile of rocks,
bend spacetime around them so that if we put in a satellite,
then it just rolls to the center,
brought in by the curvature of space time,
which is a force we call gravity.
If we push it, the satellite still experiences gravity,
but now the net effect of sideways velocity
plus that downward force
make it trace out an elliptical orbit.
As you can see, closer to the Earth,
we need to go faster to stay in orbit,
higher up, slower.
(very low music)
Very low earth orbit blends the line between satellite,
missile, and privacy violation.
In the past these used to be super useful.
Being located so close to the ground
means it can get sensitive measurements of the planet,
and get some pretty good photographs.
However, because we're still basically within the atmosphere
it means that drag is a significant issue,
requiring iron boosters and occasionally fins
to keep you stable.
There's a whole group of these satellites
that look at just like the Hubble Space Telescope,
only pointing down,
taking photographs very much like this one.
Nowadays, telescopes in higher altitude
do the job a bit better,
and apparently so do weather balloons.
Very low earth orbit, C-tier.
(international upbeat music)
The International Space Station
is a smart object in a dumb orbit, full of compromise.
When it was being designed, each partner country
wanted to have it at a different inclination,
more ideal for their own space port.
Eventually the Russians got their way with 52 degrees.
That itself was a compromise.
They actually wanted 46, but had to raise it a little
to avoid dropping their spent boosters onto China.
That was okay when it was the Russians
doing most of the launches,
but nowadays with American and European space ports
becoming more popular, they need to go out at a weird angle,
wasting lots of fuel and potential payload capacity.
D-tier, very sad astronauts.
(mega music)
Moving up, we run into literal tons of mega constellations.
These are all arranged according to different iterations
of the Walker Constellation.
Starlink is one, and Iridium is another.
The satellites need to be located rather low,
acting basically as telephone towers
to link different points on earth,
typically with a phone or internet connection.
Often a lot of capacity gets wasted at the poles,
and their functionality is never quite what was promised.
D-tier.
(sunny music)
To understand Sun Synchronous orbit
we need a bit more astrodynamics.
You might already know that the earth is a sphere,
except not quite.
(drill whirring) We got this spin.
This gives it a sort of bulge at the equator,
making gravity a little wonky.
Above the equator, this extra gravity
pulls the spaceship down, below back up.
That makes its orbit drift east or west,
depending on the direction of its orbit
relative to Earth's spin.
We call this the J2 Pertubation.
By using this perturbation to our advantage
the satellite appears to move across the sky
at the same rate as the sun,
making it revisit the same point on Earth's surface
at the same time each day.
That's brilliant and doesn't require any extra fuel.
A-tier.
(positional music)
You've probably heard of GPS, and you might even be aware
of some of non-American knockoffs, slash upgrades.
It works so that any point on Earth's surface
is visible to at least four of these satellites at any time,
allowing for you to triangulate your position.
The orbits themselves are almost perfectly circular,
orbit the earth twice per day,
and are position to mostly cancel out the J2 Perturbation.
Together giving them very reliable orbits,
and pretty accurate positioning.
Unfortunately, they don't work too well in cities
where dense buildings get to the way for signal.
Additionally, the US government limits the accuracy
to non-US military users, so overall B-tier.
(upbeat music)
Flower is just a general description
for it can be a really diverse set of constellations,
similar to the diversity of Walker,
but in my opinion, much cooler.
We call them Flower,
because from the rotating reference frame of the earth
it looks like they're doing little loops, like petals.
And then when taken together,
look like a full flower in bloom.
They were invented by a dude from Texas,
so of course he made a literal Lone Star constellation,
ripped straight from the state flag.
You could make something similar to this with Walker,
but it would almost immediately fly apart.
Because the Flower constellation is made of quite essential,
but this one can stay together.
They have to be designed by a computer
using what is effectively a refined form of guess and check.
You can optimize for whatever you like.
Say you want to do telemedicine with low latency,
high reliability links between different cities.
Yeah, you can set that up.
Want to do some nearing observations of a certain point,
combined with a few far out ones?
Yeah, that's doable too.
Comparing stats between Walker and Flower constellations,
Flower wins every time.
True, they can be a bit of a pain to set up,
but once you're there, incredible.
S-tier.
(stationary music)
As we've been getting higher and higher,
our orbits have been becoming less and less crowded,
until we reach 35,786 kilometers when we hit Geo.
This place is packed.
It is at this very specific altitude
where the orbital period of our satellite
exactly matches the rotation of the earth, one day.
From the perspective of an observer on the surface,
it looks like our satellite is synchronized
with our own movement.
If it's positioned directly above the equator,
then looks like it's stationary.
This place can be very useful,
because by pointing a receiver at the satellite,
you can just receive its signals,
without needing to track it at all.
One downside is that it doesn't work that great
at higher latitudes, where it needs to go through
much more atmosphere, and sometimes even the planet itself.
However, generally rather useful.
E-tier.
(spoopy beats)
Welcome to the graveyard orbit.
Space junk is what happens when you're expensive satellite
stops responding to your calls.
This takes up valuable orbital slots,
and can pose a serious danger for other space assets.
Therefore, when satellite reach near the end
of their useful lives, we can tell them
to either yield themselves into the ocean,
or if they're too far up,
and that would be too fuel expensive,
instead, we can get them to move the orbit
a little bit higher, into what's known as a graveyard orbit.
These things can clutter up any orbital slot,
but often cluster just beyond Geo.
Spooky, scary satellites.
F- tier.
(music to celebrate the glorious fatherland)
How'd you get nice high quality satellite TV
when you are too far north to use a geostationary orbit?
One solution used by the Russians for decades
is a Molinia orbit.
Highly elliptical whipping through the southern hemisphere
before hanging over the northern.
One issue is that it passes through the radiation soaked
Van Allen belts multiple times per day,
never good for sensitive electronics.
On top of that, you need three satellites
to get constant coverage.
C-tier.
(better communist music)
The Tundra orbit improves upon Molinia.
It's a little bit further out,
which means that it avoids the radiation belts.
And you only need two satellites to get constant coverage
of one of these high latitude regions.
From the perspective of someone on the earth,
it looks like the satellite does a little loop in the sky.
B-tier.
(city music)
You know how GPS doesn't work all that well in cities,
and how Tokyo is the most city city to have ever citied?
Well, in 2018, Japan patched themselves an upgrade
by combining three Tundra orbits and one geostationary orbit
in what's called the Quasi-Zenith Satellite System.
Doing so they can get reliable coverage,
even in the heart of Tokyo, incredible.
A-tier.
(moon music)
Let's say that you want to orbit the moon,
but not so close to the surface
that it looks like you're needy.
In that case, you'll want a distant retrograde orbit.
Artimus just used one of these one,
one of their first test flights around the moon.
The idea is that this far out from the surface,
the moon's gravity is rather weak.
And you are actually being dominated by the earth.
Because of this, your orbit is quite similar
to that of the moon,
but the moon exerts a gentle correction factor,
making the orbit wobble around a bit.
It's a pretty niche orbit,
but some very interesting optimal mechanics.
C-tier.
(the best music ever)
Lagrange points are a fascinating phenomenon,
where the gravity is of the earth and sun,
along with centrifugal force cancel out exactly.
There are five of them in the earth's sun system,
labeled L1 to L5.
L1 is the perfect place to put up a sun shield,
to help counteract the effects of climate change
and also plunge the earth into unending winter.
L2 is where we have the James Webb space telescope,
where it's able to use a single heat shield
to block out the earth, moon, and sun,
to do some ultra low temperature astronomical observations.
L3 is perfect for a space station
that officially doesn't exist.
L4 and 5 are the most gravitationally stable,
being the perfect place to act as a staging ground,
or to do asteroid mining, incredible.
S-tier.
There we have it, the definite orbit tier list.
Obviously there are loads more orbits
than just we could cover today,
but these ones are the majority that run our world,
and they look pretty cool while they do it.
This has been James Dingley from the Atomic Frontier.
Keep looking up.