Knots on Mars! (and a few thoughts on NASA's knots)

Practical Knots
1

(NOTE: All photographic images below can be clicked to view at higher resolution.)

In the last few days some of the first high resolution color images of Mars Rover Curiosity’s deck have been taken. These included some of the best images yet showing the knots visible on the exposed wire and cable bundles.

While a few of the folks here are no doubt aware, it might surprise most people to learn that knots tied in cords and thin ribbons have probably traveled on every interplanetary mission ever flown. If human civilization ends tomorrow, interplanetary landers, orbiters, and deep space probes will preserve evidence of both the oldest and newest of human technologies for millions of years..


http://www.dfred.net/misc/igkt/20120823/back-from-AWS/small/0014ML0020000000E1_DXXX-levels.jpg

Image Credit: NASA/JPL-Caltech/Malin Space Science Systemsurl=http://mars.jpl.nasa.gov/msl/multimedia/raw/?rawid=0014ML0020000000E1_DXXX&s=14[/url]

Knots are still used in this high-tech arena because cable lacing has long been the preferred cable management technique in aerospace applications. That it remains so to this day is a testament to the effectiveness of properly chosen knots tied by skilled craftspeople. It also no doubt has a bit to do with the conservative nature of aerospace design and engineering practices. Proven technologies are rarely cast aside unless they no longer fulfill requirements or there is something substantially better available.

While the knots used for cable lacing in general can be quite varied – in some cases even a bit idiosyncratic – NASA has in-house standards for the knots and methods used on their spacecraft. These are specified in NASA Technical Standard NASA-STD-8739.4 – Crimping, Interconnecting Cables, Harnesses, and Wiring. As far as I’ve been able to identify in the rover images below, all of the lacings shown are one of two of the several patterns specified in the standard.


http://www.dfred.net/misc/igkt/20120823/back-from-AWS/NASA-STD-8739.4-fig-9-2.gif

The above illustration shows the so-called “Spot Tie”. It is a clove hitch topped by two half-knots in the form of a reef (square) knot. In addition to its pure binding role, it is also used to affix cable bundles to tie-down points, as can be seen in many of the Curiosity rover images below.

Knot history buffs might find it interesting that a “Spot Tie”-like knot, with opposite Clove Hitch end orientation and topped only with a single half-knot was illustrated in 1917 by A. Hyatt Verrill under the name “Gunner’s Knot”. This was seemingly due to Verrill copying from J.T. Burgess, who had oversimplified “Bowling’s” description of what possibly was the first known textual description of the Constrictor knot. But that’s a whole different can of worms! ;D

So why has NASA standardized on this knot instead others which might serve the purpose? The following reasons are merely my own musings. I’d be interested to hear others’ comments on this knot’s strengths and weaknesses.

  • Conservative design

The Reef Knot and Clove Hitch are extremely ancient. Both were discussed in detail as surgical and orthopedic knots and slings by Greek physician Heraklas in the 1st Century AD. The Reef Knot is depicted with varying degrees of realism in ancient Egyptian statuary and hieroglyphics as far back as 4000-5000 years ago. I presume there would be little disagreement here that these two knots must be among the oldest of the purposeful, standardized knots used by humans. You simply cannot get more field-tested than this!

But why combine these two well-known old knots in a somewhat novel way that, at first, might seem a bit “belt-and-suspenders”?

  • Even pressure

The inner profile of the clove hitch is smooth. Both turns bear on the bound object evenly throughout their contact. The contact area is increased by having two turns. When the reef knot is added, the ends are pulled up and away from the object. There is some extra pressure exerted by the reef knot on the riding turn, but this is distributed onto the two underlying turns. Evenness of pressure is important for the same reasons as the next item.

  • Controlled tightening

Overtightening of cable management bindings can cause conductor breakage, insulation damage, excessive chafing, and deformations between the conductive, dielectric, and shield parts of a cable, and no doubt a host of other issues. It is one of the classic problems with ratcheting plastic cable ties (i.e. “zipties”) that they only have quantized adjustment steps and cannot be easily loosened. While zipties with a metal tooth insert do allow for smoother tightening, the possibility of this tiny metal part coming loose near electronics generally excludes their use. That zipties cannot easily be loosened or adjusted during tightening makes them more prone to being left in an overtightened state. Difficulty of adjustment might also be considered a possible strike against using the Constrictor Knot (and similar knots) for this application.

The clove hitch is not known as a particularly good binder alone, but that may be an advantage in this application. If the clove is initially made too tight it is easily loosened and readjusted. Once the proper snugness is achieved the addition of the first half-knot produces only a small and predictable amount of additional tightening. One thing I did notice in my tests is that if the first half-knot is made in the opposite orientation than shown in the standard, it tends to produce more tightening and also separates the underlying turns of the clove hitch.

  • Resilience to errors in tying

As mentioned above, I did some tests tying the knot incorrectly in different ways. While these forms generally seemed inferior to the specified knot, they were not obviously destined to fail. Using these two basic knots in a compound form seems to be a reasonable way to make errors of tying less detrimental to the resulting knot.


http://upload.wikimedia.org/wikipedia/commons/thumb/5/58/Cable-lacing-nasa-style-spot-ties.jpg/400px-Cable-lacing-nasa-style-spot-ties.jpg

Image credit: David J. Fred/Wikimedia Commons url=http://commons.wikimedia.org/wiki/File:Cable-lacing-nasa-style-spot-ties.jpg[/url]
Above is a high resolution photo taken of these Spot Ties made in Gudebrod Nomex lacing tape. These types of lacing tapes are often coated or impregnated with materials (e.g. synthetic rubbers) to increase their knot-holding properties. I’m not sure what the tapes visible on the rover are made of, but I’d suspect the material was chosen for its behavior at extremely low temperatures and pressures as well as very good UV resistance.

The keen observer may note that some of the Spot Ties in the rover images show the ends perpendicular to the cable bundle and some parallel. Based on general experience with reef and granny knots, one might be tempted to assume the parallel examples are improperly finished with granny knots. Experimentation with Nomex lacing tape seems to show that it’s more a matter of the knot preserving the orientation of the ends as the reef knot was tightened. I found that when the Spot Tie is finished improperly in the granny form but with the ends kept perpendicular to the wire bundle they tend to stay that way. While these experiments are hardly definitive, it doesn’t seem to me that one can tell from orientation of the ends whether the knot was properly tied or not.

There is also the issue of the handedness of the first half-knot with respect the ends emerging from the Clove Hitch portion. The relative orientation shown in the NASA spec does appear to be preferable to the alternative.


http://www.dfred.net/misc/igkt/20120823/back-from-AWS/NASA-STD-8739.4-fig-9-6.gif

I won’t go into much discussion about these stiches for the moment, but I believe the one on the left (the running clove hitches) appears on the extreme right edge of detail image “1” below.

And now for the pretty pictures…


http://www.dfred.net/misc/igkt/20120823/back-from-AWS/small/context_rover_deck_PIA16063_crop1_scale.jpg

Image Credit: NASA/JPL-Caltechurl=http://photojournal.jpl.nasa.gov/catalog/PIA16063[/url]
Multi-image panorama giving context of rover, deck, and its suroundings. The rim of Gale Crater is visible in the distance.


http://www.dfred.net/misc/igkt/20120823/back-from-AWS/small/context_rover_deck_PIA16063_crop2_scale_zoomboxes.jpg

Image Credit: NASA/JPL-Caltechurl=http://photojournal.jpl.nasa.gov/catalog/PIA16063[/url]
Annotated context image showing locations of following five detailed images. Outlines do not quite align to following image borders due to panorama projection.

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http://www.dfred.net/misc/igkt/20120823/back-from-AWS/small/1_0014ML0017000000E1_DXXX_crop1.levels.jpg

Image Credit: NASA/JPL-Caltech/Malin Space Science Systemsurl=http://mars.jpl.nasa.gov/msl/multimedia/raw/?rawid=0014ML0017000000E1_DXXX&s=14[/url]
Examples of one of the flat stitching methods (shown above) appear on the extreme right edge of this image.

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http://www.dfred.net/misc/igkt/20120823/back-from-AWS/small/2_0014ML0017000000E1_DXXX_crop2.levels.jpg

Image Credit: NASA/JPL-Caltech/Malin Space Science Systemsurl=http://mars.jpl.nasa.gov/msl/multimedia/raw/?rawid=0014ML0017000000E1_DXXX&s=14[/url]

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http://www.dfred.net/misc/igkt/20120823/back-from-AWS/small/3_0014ML0019000000E1_DXXX_crop1.levels.jpg

Image Credit: NASA/JPL-Caltech/Malin Space Science Systemsurl=http://mars.jpl.nasa.gov/msl/multimedia/raw/?rawid=0014ML0019000000E1_DXXX&s=14[/url]

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http://www.dfred.net/misc/igkt/20120823/back-from-AWS/small/4_0014ML0020000000E1_DXXX_crop1.levels.jpg

Image Credit: NASA/JPL-Caltech/Malin Space Science Systemsurl=http://mars.jpl.nasa.gov/msl/multimedia/raw/?rawid=0014ML0020000000E1_DXXX&s=14[/url]

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http://www.dfred.net/misc/igkt/20120823/back-from-AWS/small/5_0014ML0020000000E1_DXXX_crop_2.levels.jpg

Image Credit: NASA/JPL-Caltech/Malin Space Science Systemsurl=http://mars.jpl.nasa.gov/msl/multimedia/raw/?rawid=0014ML0020000000E1_DXXX&s=14[/url]

[Edited 2013-09-11 to move images back from AWS S3]

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Awesome ! Thank you very much dfred.

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It seems that one can learn how to travel to Mars without knowing much about hitches and - and vice versa… :slight_smile:

4

Cool, thanks!

5

Really? How does it seem so!?

???

6

Didn’t intend it for anything other than illustration. Even these newest images coming down from Mars are still not extraordinarily clear in terms of the knots. If NASA did not have a published standard, it would likely be very difficult to deduce knots being used. Since I had the image handy from the Wikipedia cable lacing article, it seemed useful to see the knots tied in similar flat material than as shown on the rover.

(It looks as though not too much more line would be consumed in making a binding like commercial fishermen use for headropes and assorted other things --line running from [i]reversed ground-line hitch[/i] to next, spiral-wrapping the bound materials between.)

I’m not familiar with that exact knot/technique. I presume is it akin to marline hitching with RGLHs instead of overhand knots?

Marline hitching, as well as a similar technique of running lock-stitches using figure-eight knots, is used extensively in cable lacing in general. The figure-eight form is indeed specified in that NASA document. (Example Wiki photo) This form is actually quite secure, easy to tighten, and holds tension well while the next stitch is made. I’d suspect the RGLH form might be even more secure. Does it tighten-up easily and evenly without much fiddling?

My suspicion as to why they use individual, unconnected knots on the deck and exposed parts of the rover is due to concerns about differential thermal expansion. The rover includes a weather station and recently measured daily low and high air temps at the landing site of -2.2C (28F) / -74.9C (-103F). Ground temperatures were measured to vary between 2.7C (37 F) / -90.9C (-131.8 F). I don’t know how the rover deck transfers heat in comparison, but there are no doubt huge temperature swings each day. If one of the running lock-stitch style of laces were used, there might be complications with the differential expansion/contraction of long lengths of the lacing material running parallel to the cable bundles. Just a guess on my part, though.

Much of the inside of the rover has active thermal controls. It would be interesting know whether that means other lacing styles are available/preferred in that more benign environment.

7

answer :
It is remarkable that the knotted/entangled part of the knot
occurs right at the gap between bound parts --i.e., at a point of
least material for clove/constrictor/… binding! Yes, tying off with the
overhand crossing atop the clove hitch --whose crossing part serves
well to brace this half-knotting– makes the binder independent
of the bound surfaces, but you need to get to that point somehow
without losing tightness of the base knot (whose engagement comes
at this remarkable place). Hence the point about the nature of the
material helps to understand how this can be done --the compresssion
of the width of the small tape whose surface is (presumed to be)
frictive enables tying over the gap; it probably also makes drawing
the binding tight more difficult --the friction hindering transfer
of tension around the bundle.

(It looks as though not too much more line would be consumed in making a binding like commercial fishermen use for headropes and assorted other things --line running from [i]reversed ground-line hitch[/i] to next, spiral-wrapping the bound materials between.)

I’m not familiar with that exact knot/technique.
I presume is it akin to marline hitching with RGLHs instead of overhand knots?

With your points taken about the benefits of individual/independent
at-point bindings, attached is an image of the (what I’ve taken to calling)
"reverse ground-line hitch --which image might be among some I’ve
posted previously (but I am not so good w/Search for such things).
nb: The wrapping/tying flow is Right-To-Left for both of these
images --a half-hitch first reversing flow, then the 2nd re-reverses
and locks the knot (a duet sometimes repeated, even more than once).

[8/27 edit to add…] This finish would seem to be a preferable,
more sure one to use on many of the friction-gripping structures
shown by Ashley in #1732..1761 --esp. #1743/47/51/52/54.

–dl*

ps : sipping some keemun + barooti tea

knots-reverse_GLHitch-4.jpg
knots-reverse_GLHitch-4.jpg888×590 37.4 KB

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Thanks dfred - an interesting read.

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Really ? Why is this so ? Where are the theoretical or experimental proofs, evidences, or even indications, about this claim ?
What we have seen is only a manual about how-to, but what about the why-so part on which this manual should have been based on ? Where are the scientific references, the experiments, the theoretical reasoning behind this decision, to use those particular hitches, and not any others ?
We wish to believe that such a technologically advanced organisation, as NASA, does everything it does the way it does only after a thorough examination of every other possible alternative, based on the most recent theoretical and experimental studies. Wishful thinking - that tends to ignore the fact that there are critical and sub-critical, or even non-critical, parts in every machine, and optimum and not optimum solutions in every technological problem. That there are good and bad solutions, decisions, tasks… and there are disasters as well as triumphs. When a hero like Armstrong dies of natural causes, we should also remember the heroes that have died at accidents because of other people s mistakes - the oxygen in the cabin, the O - ring, the loose tiles. Heroes that died because somebody told somebody else to “Take your engineering hat off and put your management hat on” . In sub-critical or non-critical parts - as the binding and the attachment of the wires inside the vehicle - this strategy works most of the time, but in some critical parts it might well fail - and it has failed tragically time and again…
So, until I see something that would really justify the use of the primordial two-half-hitches or two superimposed overhand knots solution to the wire binding and attaching problem, I will continue to see what I see : a so-so, quick and dirty way of dealing with a secondary non-critical problem - and a bureaucratic brochure that attempts to wrap the whole thing within some illustrated pages, using a superficially “scientific”-sounding language, but no scientific method at all.

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Mmmm …maybe I wouldn’t buy a second hand space module from NASA after all! Seriously it’s perhaps nice to know that NASA (like other large organisations esp government) have people writing manuals who may not have a clue what they’re talking about but once it’s in the manual it becomes received wisdom. Perhaps a Martian will see it and give us some scientific analysis (as much chance as NASA responding here I imagine! But maybe it’s all secret squirrel?)

Barry

11

Ah, yes, I misinterpreted your initial comment. Thanks for the clarification.

In addition to the mock-ups for the Wiki photos, I did the networking in a friend’s new house and laced all the permanent cabling in the wiring closet with this tape. Total overkill, I know, but it was fun/interesting for me and they were the kind of person who appreciates this kind of thing. I found it was quite suitable for the task, as one might expect. I mostly used the running figure-eight style, but did use these spot ties for affixing some of the bundles to tie-down points and found there was no problem with the clove hitch maintaining tension while finishing the tie.

BTW, I got a few spools of this tape at Boeing Surplus when I lived in Seattle. Sadly they closed several years ago, but it was an amazing place to poke around. Wish I’d bought more of it, as I suspect it is very expensive to buy new.

[...] nb: The wrapping/tying *flow* is Right-To-Left for both of these images --a [i]half-hitch[/i] first reversing flow, then the 2nd re-reverses and locks the knot (a duet sometimes repeated, even more than once).

I do like how these ties flow, and also from one to the next. One minor concern I’d have about the spiral wrapping on wire bundles is that any torsion would tend to either loosen or tighten the binding against the bundle. Don’t know how likely a scenario that is for most cable lacing, though.

BTW, I really like that second photo – with the white wraps on the cyan-colored rope – a very pretty, well-composed shot.

(Tieguanyin oolong for me today… )

12

I remember now the cable lacing from my own aircraft maintenance days. It seems that this knotting has been employed since before then (late 60’s). If memory serves well I believe the cord/lace was waxed and that aided in the knot retention.

So I wonder if the Mars Rover has waxed tape? It looks quite shiny in the posted pictures.

SS

13

It is so, because the 2nd half-hitch forms a binder
vice the simple half-hitch finish Ashley shows --i.p.,
one of the miller’s knots (in the form of the ground-line h.).
(I think that I’m partially misled in at least some of those
images by the spaced helical wrapping, which is done
for clarity but not expected to exist in the tied knot;
but even then, one can work in the 2nd half-hitch.
Otherwise (space intended), it seems to beg for this finish.)

Where are the scientific references, the experiments, the theoretical reasoning behind this decision, to use those particular hitches, and not any others ? ... So, until I see something that would [i]really[/i] justify the use of the primordial [i]two-half-hitches[/i] or two superimposed [i]overhand knots[/i] solution ... , I will continue to see what I see : a so-so, quick and dirty way of dealing with a secondary non-critical problem --and a bureaucratic brochure that attempts to wrap the whole thing within some illustrated pages, using a superficially "scientific"-sounding language, but no scientific method at all.

Your brief, equally information-lacking criticism cited by me
above (post #4 / reply #2), is stronger than a mere question
for basis : it implies that you know better --and would have
solved this problem in some other way!

Here, you sound as though you won’t be going out for a walk
any time soon unless Gauss & Reimann are reincarnated to
prove how to tie shoes validly in any possible geometry!

And yet, meanwhile, things are going far beyond a walk
in the park, into space (& back, sometimes)!

:wink:

14
There is also the issue of the handedness of the first [i]half-knot[/i] with respect the ends emerging from the [i]Clove Hitch[/i] portion.

Indeed : this essentially makes a squaREef structure.
(And was considered to be the constrictor knot verbally
introduced by “Bowling” as “gunner’s knot” --a Verrill mistake
brought into graphics.)

(the running clove hitches)

Note that the structure implies that the “running”
isn’t of cloves but of an orientation of the overhand
binding a pass of the other line --which pair of lines begin
from a clove hitch and finish with a pseudo-cloveness
akin to what I described in another thread about finishing
west country whipping with a (pseudo-)constrictor knot
–i.e., of mimicking the single-strand knot with two strands.

–dl*

15

I was not talking, of course, about the common knowledge that, most of the time, two good things are better than one good thing ! :slight_smile: I was talking about the evaluation of all Ashley s and non-Ashley s hitches, that is obviously missing. Unless there are classified knotting secrets, which would be revealed after a century or so - about the time I reckon you will publish your own notebooks :).

So, you admit that the manual is (scientific) information-lacking…That was my point, was nt it ?

It states that NASA should know better, of that NASA should tell us about what it knows, about the theoretical or experimental evidence that support the selection of the particular hitches, and not of any other else.
I am not an expert on knots - but if I were, I would have expected that NASA would have asked my opinion, or refer to my published work. Of course, if knotting solutions are classified, you would nt allowed to tell us that NASA has asked YOUR opinion, would you ? :slight_smile: And that is a reason you should publish your notebooks before the MANNED NASA trip to Mars ! :slight_smile:

If I were to walk on Mars, I would expect ( and feel much safer if that has been assured…) that somebody had examined the shoes I will wear there - and had not put me in his grandfather ( 1915 ?? ) boots ! :slight_smile: Because if you happen to be into the wrong shoes on Mars, you will not going to be reincarnated on Earth any time soon to publish your notebooks, believe me…

I am not convinced by the quick and dirty, not-clever knotting “solution” to this non-critical, secondary knotting problem, and I have not bought the (scientific) information-lacking manual or the glossy pictures. If a similarly quick and dirty, not-clever solution would have been chosen ( should I better say “picked out”, without any theoretical or experimental examination ) for a critical, main problem of the mission ( like the oxygen in the cabin, the O-ring, or the lose tiles ), I would not be happy to be on board, because sometimes quick and dirty, not-clever solutions are /were responsible for things/people that are /were NOT going to be back anytime soon - and neither would be you, I suppose.

There are two philosophies in life : The one says, pay the proper amount of attention to each part of life, according to the value it has in your life. ( A time-saving philosophy ). The other says, give as much attention as you can in every part of your life - because you can not know, in advance, which is, or will be someday proven to be, of the greater value - and because, perhaps, everything deserves to be dealt with our attention, because everything has a value that is related with the value if everything else. ( A soul-saving philosophy).
We are talking about KNOTS here… in Earth ( or Mars, or everywhere else in the Universe where there might be some form of intelligent life…) 99.99 % of the people do LAUGH when we tell them that we are paying as much attention to knots, as we do. Do knots have a value ? Should we lose our valuable time exploring knots ? Will Ashley congratulate us, when he will come back from his walk ? I do not know. I pay attention to knots, because I like them. That was what Gauss and Riemann did, for the things they did like, and what my grandfather and father did, and what I hope my son will do, too.

( My humble advice to knot tyers is to try to learn about hitches by reading books, or tying their own - and not copying and pasting this “solution” NASA has happened to pick out, for unknown reasons.)

16

Actually, I don’t agree with this in full, and had some time
of self-challenge on how adding a 2nd of something I was
finding deficient could do anything but put some trifling delay
in inevitable failure --that, okay, now the 2nd/last-done H-H
must loosen before the given one does, but then it does !?
Analysis IMO shows that the 2nd H-H imparts some tightening
and curvature into the first to increase its nip, and in some
cases there is also some friction added by parts now being
adjacent (there being 2 vs. 1).

I was talking about the evaluation of [i][b]all[/b][/i] Ashley's and non-Ashley's hitches, that is obviously missing. Unless there are classified knotting secrets, which would be revealed after a century or so - about the time I reckon you will publish your own notebooks :). /// So, you admit that the manual is (scientific) information-lacking... That was my point, was nt it ?

As though one should expect any manual to contain such detailed
rationale!!! Still, that wasn’t the form/diction of your remark,
but rather a presumption of inferiority --not the mere lack of
some proof. Where, btw, do you ever see this given for knots,
so that we might suggest a model for it ? --or do you continue
to wear slippers/loafers, to keep on the safe side?!

[quote="Dan_Lehman post:13, topic:4519"] it implies that you [u]know better[/u] --and would have solved this problem in some other way! [/quote] It states that NASA should know better, or that NASA should tell us about what it knows, about the theoretical or experimental evidence that support the selection of the particular hitches, and not of any other else.

Again, hardly to be expected in a manual of instruction,
and not quite the terms of your point --or in that “should
know better” there is implicit assumption that some “better”
exists, and that begs an answer from who asserts it, not NASA.

And that is a reason you should publish your notebooks before the MANNED NASA trip to Mars ! :)

My notes are now primarily just images of structures.
And I’ve remarked to myself about my “QRS” so-far format
being nearly entirely graphical vs. verbal, and the loss of
information (tied in what cordage, loaded or what minimal
experience with …) is bad --a loss. But I have some desire’
for the purity/cleaness/objectiveness of presenting just
an image ; let commentary come as it may beyond that … .

I am not convinced by the quick and dirty, not-clever knotting "solution" to this non-critical, secondary knotting problem,...

If indeed this is Q&D, and has made the rounds in many
instances w/o hint of problem, why would you devote any
research hours to proving its evident working, or to seek
an alternative? As you note, this binding doesn’t have
anything like the importance of those O-rings (which were
functionally noted to be an issue, but overruled --without
consequence, ultimately, but for conscience?-- on other
grounds, tragically. But perhaps NASA has done some
vibration testing of such bindings, to assure themselves
of the working.

My humble advice to knot tyers is to try to [u]learn about hitches by reading books[/u], or tying their own - and not copying and pasting this "solution" NASA has happened to pick out, for unknown reasons.

And what will which books teach you about hitches?
(Will you find anything about the NASA hitches anywhere?)

–dl*

[8/27 edit : “could to” => “could DO” ]

17

Perhaps I should not say what I am going to say, but let it be : This "two half-hitches" thing is nothing but a knotting paradox ! :slight_smile: In such a situation, the first/inner knot is, in fact, nothing but a nipping loop, and only the second/outer one is a genuine half-hitch. If the two knots remain adjacent to each other - which can only mean that both legs of the inner knot remain under tension - the inner knot is not able to hitch the rope 100%, so it is not a hitch…

One should expect from a " NASA Technical Standard" to refer to some published scientific work, yes - unless hitches can be used by extra-terrestrial terrorists as a lethal weapon against Earthmen ! :slight_smile: Even if it is not given anywhere, I hope that somewhere , sometime, somebody will offer such a proof - and if this somebody will not be the “superior” NASA, who will ?

So, you are convinced that there is - and there will be - NOTHING better, never…and that solution is the “superior” , the only one, carved in stone and offered to us by the KnotGod… Perhaps you are secretly informed by somebody, about things we are mot allowed to know… :slight_smile:
No, it is the responsibility of the expert to refer to evidences, indications or proofs about what he claims is the optimum option, not of the layman…It is the responsibility of the doctor, not of the patient ! If you are ready/happy to swallow anything that is sold to you, without any reasoning, by people that are paid by your taxes, please, let me prefer my safe slippers/loafers… :slight_smile:
The number of the known hitches is about one hundred or so (?). It would have been NOT a big deal, if they had examined all those knots in detail, qualitatively, on a variety of materials and temperature/vibration conditions. THAT would have convinced me that they know what they are doing, and why they are doing it so - even in this non-critical, secondary issue - and I would had felt that your money are not spent on multi-pages blah-blah.

I do not believe that we came down from the trees, or gone up to Mars, because there was something that " was not working " up there or down here. In NASA words, what drives us is “Curiosity” ! We were devoting thousands of hours to prove, again and again, that the Pythagorean Theorem was, evidently, working - until Gauss and Riemann went out of their safe slippers/loafers, and figured out an alternative to Euclidean Geometry.
I am curious about all the simple knots that may exist, and I would be really happy if I could learn them all, and then settle to the few that would have been proved to be the best ones…Evidently, all sufficiently tangled ropes form sufficiently working knots - but that is not what we are talking about in this Forum, I hope.

I am sure about it - but then, why on Earth or Mars they are keeping us in the darkness ? It would be so useful if they had published the results of those tests, and the alternative hitches they had tested and evaluated before they had settled to the particular solution.

18

May I suggest ABOK #1244 for NASA, it rivals the Constrictor in my experiences and would seem much better than the one they’re currently using. My suggestion would also save precious space time, assuming they’re tying these in space at some points.

ABOK #1244 isn’t far behind the common Constrictor as far as security and binding power…and it can be tied in the bight!

19

Are you recommending a slipped knot for NASA?

Tying in the bight looks to be an unusable attribute for
most of what I’m seeing in NASA’s binding. (Interestingly,
the un-slipped knot (~= #1674) is also TIB (tyable inthe bight) [sic].

(Btw, more than the constrictor does, #1674 puts the
tails’ nips farther from the tangent point of a line of tension
in setting the knot, so there is some degree of resistance
to being set tight (unless one pulls around the object
with resistance for it). What I mean is that if the tangent
point to the setting axis of tension were 12:00, one would
find that the extent of the knotted parts puts the nips on
the two ends at, say, 11:56 & 12:04, requiring some bit
of deflection over this short arc, and maybe leaving some
slight, relative looseness therein.)

–dl*

20

Yes, of course #1674, sorry I didn’t clarify..no slipped knot suggestion here.

I think more than anything this NASA Knot just goes to show that they haven’t exactly done their homework on knot efficiency. There’s so many better options in this situation than what they’re using. JMO.