
Why Does the International Space Station Have That Shape? - curtis
http://gizmodo.com/why-does-the-international-space-station-have-such-a-we-1692193163
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notahacker
I was hoping to see the famous story of path dependency that traces the
dimensions of shuttles back through the history of rail gauges back to Roman
chariots and the width of two horses
[http://www.astrodigital.org/space/stshorse.html](http://www.astrodigital.org/space/stshorse.html)

~~~
bradleyland
Famous, but full of "fudged" facts that make that version of the story more
interesting. Snopes has a full drill down.

[http://www.snopes.com/history/american/gauge.asp](http://www.snopes.com/history/american/gauge.asp)

~~~
flinty
I was hoping to see the snopes link as a rebuttal.

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gregschlom
The video at the end of the article is absolutely fascinating.

Also, it's the first time I hear that rejecting heat is a big deal in space.
If anything, I would have assumed that heating the station would have been a
problem, rather than keeping it cold.

~~~
wmil
Most people assume that, and most sci-fi reinforces that opinion. But a
generic Thermos is a vacuum flask.

Space is an incredible insulator. The only way to cool things is to radiate
heat.

~~~
s_kilk
The sci-fi game series Mass Effect had a good explaination for this, and tied
it in with the notion of ships having recognizable "signatures":

[http://masseffect.wikia.com/wiki/Codex/Ships_and_Vehicles#St...](http://masseffect.wikia.com/wiki/Codex/Ships_and_Vehicles#Starships:_Heat_Management)

~~~
golergka
It also works similarly in Eve Online, btw.

~~~
s_kilk
Indeed, whenever corp-mates would ask why there are brightly lit "windows" on
their ships I would point out that they were actually heat dissipation panels.

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jccooper
One factor in the shape of the station that's not commonly known is actually
aerodynamics. The ISS is in a rather low orbit (mostly to make getting there
easier) so aerodynamic drag is a noticeable (if small) force.

The station is thus laid out kind of "flat" to present a reasonably compact
frontal area. (This also helps with orbital debris encounters.) The solar
array positioning does commonly conflict with the aerodynamics, but minimizing
that is one of the factors in their positioning software.

The fore/aft view is not very popular, because it doesn't look as impressive,
but here's one: [http://www.extremetech.com/wp-
content/uploads/2011/06/ISS_Ba...](http://www.extremetech.com/wp-
content/uploads/2011/06/ISS_Backdropped_by_Space_and_Earth.jpg)

That's the orientation the ISS travels in--i.e., what "stationary" air sees as
it zooms past.

~~~
sitharus
It's also the reason for Night Glider Mode:
[https://en.wikipedia.org/wiki/Night_Glider_mode](https://en.wikipedia.org/wiki/Night_Glider_mode)

Laying the panels 'flat' with regards to the orbit saves significant amounts
of fuel. There's also a mode where they do the same during the day if there's
a critical shortage of fuel.

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tajen
I'm wondering about rotation and trajectory. Do they have engines on the craft
to maintain its trajectory? But then if they thrust from one module, given all
modules aren't aligned with each other, that implies thurst creates a rotation
of the craft, so do they have two engines for each dimension?

Same question for solar panels: Do they let them rotate so at odd times
they're exactly flat in the plane of the sun and receiving 0% energy, or do
they rotate other modules of the spacecraft so that the solar panels are
always at the sun?

~~~
Already__Taken
I know NASa had a competition running for the public to see if anyone could
find a more optimum way of rotating the solar arrays on the station to improve
power.

They detailed some crazy restrictions like how the panels have to be heated
evenly so the thermal expansion does not rip them apart.

ahh heres a link: [http://www.topcoder.com/iss/challenge-
details/](http://www.topcoder.com/iss/challenge-details/)

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personjerry
I found it surprising how much of this I knew from my hours spent playing
Kerbal Space Program!

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na85
I'm sure the shape is only weird to those who haven't pondered the economics
of designing something to withstand the near-vacuum of low earth orbit.

~~~
darklajid
Which, incidentally, is probably the majority of the people, ~everyone~.
Explaining the question quite well in my opinion?

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golergka
As with many other questions regarding space exploration, it seems almost
intuitive and obvious after playing KSP.

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TeMPOraL
Exactly. Few dozen hours spent in that game will teach you more about space
than... pretty much anything.

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rgawdzik
I'm sure if the budget was there, NASA would worry about aesthetics.

~~~
ars
That's how to tell if a technology is complete.

When computers started they were beige boxes, now they are decorated and
colorful - so we know they are done.

People worry about how phones look, so those are done.

The first smart watches were functional, now they worry more about aesthetics,
but none are actually on the market. So that technology is not done, but is
getting close.

Cars have been all about aesthetics for decades now.

Etc, etc.

(Don't assume "complete" means they don't improve them, it just means any
further changes are minor, and mostly unimportant.)

Airplanes for example seem like they are done - but they are not sold on
looks, so they are not actually done. (Maybe a little bit on the inside?)

~~~
mrottenkolber
Disagree strongly. Computers are way uglier now than they were in the 90s
(beige boxes).

There is an arc in every art. It starts with the bare bone essentials,
exposing the spirit and greatness. Then it becomes popular and amasses cruft
until its unbearably overloaded and ugly. Then it gets stripped back to its
original form, regaining its glory. And then we repeat.

~~~
theandrewbailey
Agreed. I started noticing 5 years ago that laptops started getting really...
I don't know, tacky? Not to mention the dozens of stickers that no one thinks
to peel off.

Also, anything marketed towards gamers tends to look like it has enough pieces
and glow so much that it might be mistaken for a nuclear reactor.

~~~
comex
Depends on the manufacturer, of course. Apple's laptop visual design over the
last decade or so has been basically conservative, but you can really see the
improvement from the original MacBook Pro from 2006:

[http://upload.wikimedia.org/wikipedia/commons/2/24/MacBook_P...](http://upload.wikimedia.org/wikipedia/commons/2/24/MacBook_Pro_situated_on_a_wooden_table.jpg)

to the unibody one in 2008:

[http://upload.wikimedia.org/wikipedia/commons/2/2e/Unibody_M...](http://upload.wikimedia.org/wikipedia/commons/2/2e/Unibody_MacBook_Pro.jpg)

Today's MacBook Pros look quite similar to that one (aside from being much
thinner), but the light has been dropped, the power button has moved to the
keyboard, and the "MacBook Pro" branding below the screen has been removed,
resulting in a slightly cleaner look.

The new MacBook is a more dramatic change: it will bring the branding back,
offer three metal colors, and cram the keyboard into the body in a way that
looks slightly awkward to me, but has the obvious advantage of minimizing the
physical size of the device. Time will tell how well its design holds up.

[http://images.apple.com/v/macbook/b/overview/images/overview...](http://images.apple.com/v/macbook/b/overview/images/overview_keyboard_on_medium_2x.jpg)

(No stickers, of course!)

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aidos
Are solar array almost like a film? I thought they sort of folded but in the
animation they look like they can almost roll them up (I know it's just an
animation, but it left me wondering).

~~~
adventured
Here's a great look at one set, that was damaged:

[http://upload.wikimedia.org/wikipedia/commons/2/25/STS120Sol...](http://upload.wikimedia.org/wikipedia/commons/2/25/STS120SolarPanel.jpg)

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rwmj
Can someone explain what "pluming" means?

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danepowell
I'm guessing it refers to the problem when docking the shuttle or other
spacecraft of making sure that thruster exhaust is never directed towards the
station itself. I remember seeing a video that showed the shuttle approaching
the station on a nautilus-shell sort of trajectory, so that thruster fire was
always directed out and away from the station.

Apart from the obvious danger of impact from ice and other debris from
thrusters, unburnt hydrazine is nasty stuff- you don't want to deposit any on
the station, only to have an astronaut on EVA scrape some off by accident and
bring it back inside.

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mrottenkolber
Who called it ugly? I think its looking awesome.

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scarygliders
First thing that popped into my head was "This might be an article about why
we don't have a Rotating Wheel space station" (mostly cost and ability to
transport the necessary parts into orbit, and some other technical details).

The article itself explains the layout of the ISS nicely though.

I'd still like to see the construction of a rotating wheel station some day ;)

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Already__Taken
A little bit of me would like to see that animation at the end with RTS like
stats changing with regards to resource capacity,use and the cost going up.

I see they added a solar array whilst for a period closing the one on top of
the station. I wonder if they had to make do for a period or the new array was
much improved it didn't matter much.

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junto
Looking forward to the day when you can just deploy an army of mini robots
that 3d print their way along building the hull as they go.

~~~
neohaven
You'd need to bring the metal up before anyway, in that case. It doesn't
really solve the major problem.

It would be easier to build them on earth still.

~~~
outworlder
Oh, but it does. Parts and components usually aren't very space-efficient,
specially when shipped together with other parts. Look at any toolbox, there
is a lot of wasted empty space.

Instead, you'd ship a lump of whatever material is required by your printer,
and manufacture whatever is needed, on demand.

It's more compact and more versatile, what's not to like? Weight is at a
premium when you are talking about payloads, but so is space.

~~~
Symmetry
You could also, in theory, use the non-fuel part of the rocket stage that
brought you up for building material. Some people have actually proposed using
empty fuel tanks for living space but this would be better.

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jkot
Other issue is de-orbiting and module replacement. Monolitic station would be
very dangerous and maintenance nightmare.

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IvyMike
I always kinda wonder how much wiggle it has. I mean, like, if you bounce off
a wall, how much does the thing vibrate?

~~~
nialo
This is actually a straightforward question to answer, I think:

By conservation of momentum, the center of gravity of the entire ISS +
astronaut system needs to stay on the same path before and after your wall
bounce. So, the momentum change for the ISS is equal in magnitude but opposite
in direction to the momentum change for the astronaut, and the velocity change
will be the velocity change for the astronaut times astronaut mass/ISS mass

Getting actual numbers to plug in left as an exercise for the reader.

~~~
Thrymr
That doesn't tell you whether you will start the station oscillating in some
mode of vibration. For that you'd need a model of the stiffness and structure
of the station.

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mu_killnine
The author makes a point about cooling the station through the use of
radiators.

How do radiators work in the vacuum of space?

~~~
danepowell
Thermal radiation is an order of magnitude less efficient than other forms of
heat transfer, but it gets the job done. It helps that you're radiating to the
dead of space, which is near absolute zero (efficiency is dependent on the
black-body temperature of what you're radiating "to").

That's the why the radiators have to be so huge, and are kept out of direct
sunlight.

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zkhalique
I always wondered why real-life space stations don't seem to have the sleek
exteriors, pleasing or even consistent patterns, but seem to have a bunch of
irregularities, and ugly-looking metal structures of different shades of beige
protruding from the hull. How do you explain that?

~~~
jccooper
The reason to have sleek exteriors or to look cool is because you need be
aerodynamic (because you're in the air) or need to look cool (because you're
in a movie, or you're a consumer good).

Being neither in much air nor in a movie nor a consumer good, real spacecraft
don't bother with expensive, constrictive, and (more importantly) heavy
exterior shells. Instead, form follows function.

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Ezhik
I don't know, I like the shape. It's actually kinda symmetrical, so it's
great!

~~~
Klathmon
There was a portion of time where there were 2 solar arrays on one side, and
one on the other.

That was annoying...

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smackfu
It's remarkably close the Space Station Freedom design from 1987, nearly 30
years ago.

[http://www.astronautix.com/craft/spaeedom.htm](http://www.astronautix.com/craft/spaeedom.htm)

~~~
rbanffy
This is not surprising. ISS and Freedom are closely related and subject to the
same engineering constraints.

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BaconJuice
I'm not following the rejection of heat, can someone explain that to me? I
thought it was cold out there and heat had to be generated?

~~~
NamTaf
Heat is transferred via 3 mechanisms:

1) Convection, i.e.: the mixing of bits of 'hot' material and 'cold' material
such as the material itself mixes through. Think blowing an air conditioner in
a room.

2) Conduction, i.e.: the flow of heat energy through matter that is touching.
The matter itself doesn't mix, but the heat energy can transfer. Think putting
your hand on a hot plate.

3) Radiation, i.e.: the energy turning into electromagnetic radiation and
beaming through the vacuum of space until it strikes something. Think
sunlight.

1 and 2 are out, as there's no matter (air, etc.) around the ISS for it to
convect or conduct with. Thus, all heat must be radiated. The above list ranks
them in order of efficiency, so heat rejection is in fact very difficult.

~~~
pvaldes
mmh... interesting problem. I wonder if satelites could just put the heat in
some not-more-needed stuff, gas or something and simply shoot or launch this
stuff to the space.

Yes I'm inventing the "farting satellite" :-).

Another possibility could be to put "hair" (short metallic spikes) about lets
say the 50% of the surfaces of the satellite. Several possible goals could be
achieved with this idea, creating lots of dynamic shadows around the surface,
protecting the real surface from small impacts (some bend spikes is better
that having a hole in your roof, and maybe even to provide support to the
ocassional human intervention out (you could substitute the spikes by a matrix
of handles easy to grasp).

Just some crazy ideas. If you need to loose heat look at how birds and mammals
do this task with movile hairs and feathers.

~~~
cesarb
> I wonder if satelites could just put the heat in some not-more-needed stuff,
> gas or something and simply shoot or launch this stuff to the space.

The astronauts actually did that on the moon! Their spacesuits used
sublimation of water ice for cooling.

Your limitation is coolant mass. The useful life of satellites is often linked
to the amount of propellant they have left; you'd have the same problem with
your proposed cooling system.

~~~
pvaldes
Wow, you need ice to take a walk in the cold moon? this is one of those smart
tricks that we, common people, never, ever will suspect :-)

okay so... so the goal is to be able to cool quickly our station in case of
emergency. We had running out of coolant gasses and so and we have "unlimited"
access to the materials in the space: "nothing" and sun radiation.

I wonder if there is a way to reduce the vibration of heated atoms with
electricity, magnetic fields or whatever electronics can do?

Is there a physicist in the house?

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peter303
Ditto for the Mirs and Tiangongs. They only had 2 to 6 sausages. The ISS is
more of a Swiss army knife.

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datsun
Interesting article. It's amazing how humans manage to engineer and build such
complex systems.

