
Cable lacing on the Curiosity rover - gameshot911
http://igkt.net/sm/index.php?topic=4028
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marshray
If an advanced alien species someday finds this rover on Mars (or probably any
other space probe launched by NASA) and examines it, what will this method of
knotting tell them about the state of human mathematics?

For example, is it possible that there exists another, more optimal, type of
knot that we should have chosen had only our knot theory had been more
advanced?

~~~
nicklaforge
"Knot theory" always concerns strings that are joined at either end to form a
closed circuit. Regardless, I don't think abstract mathematics does much for
you when the problem is so simple and 'practical'.

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johnchristopher
Why are the cables exposed ? Wouldn't it better to fix them inside the rover
and only have the relevant ends pop out when there is a need to connect to a
device located on the outside of the shell in order to reduce interferences
and external damages ?

~~~
natep
My guess is that they have cables on the outside _and_ inside, and putting yet
another cover over the outside cables would mean more mass. As-is, they only
have to worry about wind and sand, so extra metal shielding is probably not
necessary.

~~~
lttlrck
Right. If they didn't care about weight they'd have used zip ties and
braiding.

~~~
natep
Not sure what braiding entails, but according to TFA, they would not have used
zip ties. And if by braiding you mean twisted, shielded pairs, then I'm sure
they used that.

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ivix
Does anyone know why so much cabling on Curiosity is on top of the vehicle,
exposed to the elements?

Surely it would be safer to contain those cables in the body? It would just
take a rock to fall on the rover from a cliffside or similar to damage those
cables.

~~~
noonespecial
For just a moment, I found myself worried about how they would hold up when it
rained...

~~~
startupfounder
Wouldn't that be a nice problem to have. The only way to fix it would be to
send some humans to the rover for a repair job...

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eckyptang
Just had to post this photo which I found after looking around as it's
related:

[http://upload.wikimedia.org/wikipedia/commons/4/46/System_Te...](http://upload.wikimedia.org/wikipedia/commons/4/46/System_Test_of_the_Saturn_V_Instrument_Unit_%286861934%29.jpg)

Saturn V instrument unit.

Awesome piece of engineering.

~~~
snowwrestler
Cool picture. It looks to me like most of those long-running cable bundles are
secured with black plastic zip ties--ironic given the text of the article.

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svdad
This is awesome. I'm going to lace all my cables now.

In these kinds of applications, what do they use to attach the cables to
something? It looks like on the rover they have special tie points built onto
the rover surface -- is that what is done in other applications too?

~~~
stewartbutler
Either they are laced parallel to a support strut, which can be thought of as
a very hard wire, or lashed down to some support point. You can also see this
in large data centers.

<http://www.reddit.com/r/cableporn>

~~~
eckyptang
Great link. There goes my afternoon :-)

The first item is amazing as well (ST-124-M3 inertial platform i.e. Gimbal
unit for Saturn V)

About: <http://en.wikipedia.org/wiki/ST-124-M3_inertial_platform>

Pron:
[https://upload.wikimedia.org/wikipedia/commons/4/44/ST-124_u...](https://upload.wikimedia.org/wikipedia/commons/4/44/ST-124_uncovered_%28IMGP3445%29.JPG)

This sort of engineering is as much art as engineering and I truly respect the
people who designed and built it.

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towndrunk
If anyone is interested in more of these standard practices in regards to
aircraft construction the following book details the proper methods that
should be used.

[http://www.amazon.com/Standard-Aircraft-Handbook-
Mechanics-T...](http://www.amazon.com/Standard-Aircraft-Handbook-Mechanics-
Technicians/dp/0071348360/ref=sr_1_2?ie=UTF8&qid=1346765869&sr=8-2&keywords=aircraft+standard+practices)

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antsam
An entire forum about knot tying?! Sign me up!

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delinquentme
Can I get an explanation as to how the OP is making the claim that these are
IN FACT these kind of knots? I mean I cannot see how this image is of
sufficient resolution to support this.

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ktizo
I love the fact that there are people, who when faced with photographs sent
from a robot on mars, will crop out all the bits of image with mars in them,
so they can get a better look at the knots used to tie all the cables down.
They must have absolutely immaculate sock drawers.

~~~
flatline3
Your backhanded compliment is a bit disturbing for being the top comment. I've
largely dismissed the complaints about the HN community becoming more
negative, largely thinking that mature realism was being mistaken for
unwarranted negativity.

However, this comment, along with the negative comments about the uptime of
Tindie's _blog_ (<http://news.ycombinator.com/item?id=4472348>), has me
thinking that these complaints of undue negativity are justified.

I find the attention to detail involved in selecting _knots_ to be a
tremendously interesting aspect of sending a physical vehicle to mars, and I
find it to be a testament to human specialization and intelligence that
there's a whole community of _knot_ experts that can provide so much insight
into the knot choices. Implying some sort of OCD around sock drawers seems
incredibly rude, and counter-productive to building or maintaining a culture
of technical excellence.

~~~
libria
I've read and reread ktizo and I'm not seeing the negativity. He drew a
correlation based on their attention to detail and if mistaken should be about
as insulting as mathematical error.

Perhaps there's a cross-cultural interpretation associated with sock drawers
that I'm missing. Granted there has been negativity on HN lately, but are we
not manufacturing drama here?

//edit: I read it that he's impressed with their focus and passion, which
sounds more like a compliment.

~~~
flatline3
"I love that ..." is the rhetorical equivalent of "Don't take this the wrong
way, but ..."

There's a pretty clear implication that it's silly to "crop out" pictures of
mars, focus on knots, and the kind of people that would do that would be OCD
in their maintenance of sock drawers.

It's a silly, vaguely cutting generalization. Observe the top reply, which
takes a defensive stance: <http://news.ycombinator.com/item?id=4474178>

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kghose
Two words: zip tie.

~~~
sosuke
Perhaps zip ties can't withstand the changes in pressures or heat. Expansion,
contraction, and all that mess. I'm simply arm chair guessing here.

~~~
kghose
Well, neither wikipedia nor the linked article say why zip ties aren't used. I
don't know what material the lacing is made from, but unless it is a natural
thread I'm sure zip ties can be made from that material.

It might be that tension (which is what I worry about when I zip tie delicate
things like optic fibre) is better controlled in hand tied knots, but zip ties
can be tied pretty precisely.

~~~
ars
"but unless it is a natural thread I'm sure zip ties can be made from that
material"

A zip tie requires a different combination of compression strength, tensile
strength, and elongation stability compared with lacing. So the materials are
not interchangeable.

Also, individual fibers bundled into a cable is MUCH MUCH stronger than the
exact same amount of material as a single homogeneous cable.

And individual fibers can handle flexing and vibration far far better than a
single large strand.

