Here’s a beautiful piece of late-60s craftsmanship: the ST-124-M3 inertial platform, a component of the Saturn V rocket’s guidance system…
http://upload.wikimedia.org/wikipedia/commons/thumb/4/44/ST-124_uncovered_(IMGP3445).JPG/400px-ST-124_uncovered_(IMGP3445).JPG
Image credit: EdgarDurbin/Wikimedia Commons
These cable management knots have indeed been used and documented for much longer. The lineage of some of the lacing knots shown in the NASA standard appear to date back at least to the early days of telephony. I haven’t yet found any documentation on cable management in telegraphy, but it would not surprise me if some of them go back that far. We can only hope that someday a researcher might even find the elusive Lineman’s Rider lurking in one of these old telco references! In any case, one finds more than a few similarities between the knots used on Curiosity and those recommended to telephone linemen in the early part of the 20th century.
Compare the knots in these 100+ year-old documents:
Popular Mechanics (May 1905), “Cable Sewing Knots”, bottom of page
Telephony (February 1907), “Manson’s Practical Suggestions” (Part 1)
Telephony (March 1907), “Manson’s Practical Suggestions” (Part 2)
…to these modern references:
Australian Civil Aviation Safety Authority (1998?), AC 21-99 Aircraft Wiring and Bonding,Sect 2 Chap 8
Qwest Corporation (2007), “Qwest Corporation Technical Publication - Telecommunications Equipment Installation Guidelines” pp. 5-19 ? 5-24
NASA (2011) NASA-STD 8739.4 - Crimping, Interconnecting Cables, Harnesses, and Wiring, pp. 40-44.
I find it quite interesting that several patterns not frequently found and/or recommended in general knotting literature are repeated in various forms:
-
Regular use of Double Strap Hitch (#1695, but by threading the ends). (C.L. Day called this knot “comparatively useless” in 1935!)
-
A binding knot/hitch topped by one or more overhand knots. (however, note the unusual underlying hitch in the older documents*)
-
Overhand and reef knots being used as stoppers at the end of tensioned doubled cords. (e.g.: finish of right-hand flat stitch in first post)
(* If I’m interpreting things correctly, it seems to be #1242 with the one of the two wrapping turns “hopped” over the other. Removed from the spar it is a figure-eight knot. It is also tied in the “reverse” manner, if I’m using/understanding Dan’s terminology correctly, like the so-called Reverse Ground-line Hitch. That is, the working end and standing ends are swapped as compared to how one might normally tie the hitch form of the knot. The clearest illustration is the one shown in Popular Mechanics.)
There seems to be some evidence that the repertoire of cable management knots have evolved in isolation from those commonly known and used for general knotting. These cable lacing knots might even provide an interesting case study for Pieter van de Griend’s ideas on “Knot Knowledge Management” (KKM). Or, to echo Budworth’s query, what if Ashley had been a lineman? ![]()
While some folks in this thread have suggested alternative knots for cable management, I actually find it quite fascinating that specific knot “user groups” tend to continue using the same related set of knots over very long time periods. This seems to be true of humans’ use of knots in general. Anyone who has seriously studied knots and is familiar with a large range of them will, of course, have alternatives immediately spring to mind when they see a knot problem. However, it seems to me these kinds of people have always represented an extreme minority of actual knot users. But that line of thinking is getting a bit far-afield from the topic of this thread…
[And also on an editorial note, the question that X1 has brought up in this thread is actually an extremely important one. It is perhaps the most important question we as knot-interested people face: what is the reason for the lack of scientific progress in understanding of the behavior of real, physical knots? While arguably they might be held to a higher standard, this lack of progress is not specific to NASA/JPL. It seems to me to be a failing of imagination to realize that there can be a science of physical knot behavior, knot physics, knot mechanics, or Physical Knot Theory, if you will. While there have been fits and starts, in the form of isolated scientific papers, no self-sustaining progress has really ever been made. It is the area of knotting I am personally most interested in. If people want to discuss the way forward on this important and neglected subject, it really belongs in–and deserves–its own thread.]
...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.
It seems unlikely to me that NASA/JPL would have used a natural fiber. However waxed linen and polyester appear to still be the preferred cordage in telephony and one can still find it sold for that purpose. The wax may serve multiple purposes: knot holding, lubricant, and also to help the natural fiber resist rot/mold – much the same as tar is used on hemp. Regarding the lubricant function, if you look at the lashings used to affix large telephone cable bundles to support structures, lengths of the cord must be pulled between tightly packed cables with flat hook/loop tools. The wax might help ease the passage as well as avoid the cord melting/sawing its way into the insulation.
As far as what they’re using on the exposed portion of the rover, I don’t know. It is quite possible it has some sort of coating for knot-retention, as mentioned in the original posting. Here’s a link to a current manufacturer’s selection of lacing tapes and coatings showing the variety of both fiber and coatings.
The rover’s lacings could be almost anything, as neither cost nor “exoticness” are likely deal-breakers in their selection process. As far as “normal” fibers I might guess either UHMWPE or braided continuous filament fiberglass, both for their UV resistance. I don’t know if the latter can be knotted in the manner shown without excessive fiber breakage, but it would no doubt be very shiny. There is also the issue of thermal cycling, for which I don’ really have any data on how different materials might fare.
(EDIT: further reading indicates telcos now may use waxed polyester lacing cord, also fixed name of ST-124-M3, also it was Popular Mechanics not SciAm)