The BBC's Europe to make more hardware for American Moon missions says that three more service modules for the Orion Crew Capsule have been ordered by NASA, bringing the total desired to six.

I noticed that the design includes some very fancy looking strutwork between the top and bottom circular plates. It looks like there are six pairs of struts around the circumference, each having some kind of circular device in the middle of the length of the strut. Perhaps it's a shock absorber or a linear motor or a super-fancy strain gauge, or something else entirely.

Then across each pair of struts is a second cross-like structure of elaborate design and construction.

Question: How do all these struts and crosses work together? Beside transmitting vertical loads between the top and bottom of the service module, what do they do? What are those squat cylindrical devices in the center of each strut connecting the top and bottom plates?

European Service Module test article

Source: European Service Module test article

See also Service Module Overview and European Service Module.

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    $\begingroup$ So a couple things I noticed that might give clues -- while it's not visible in the picture posted here, on the image in the first link, you can see the steel item in the center has right-handed (acme?) threads on the top stud and left-handed threads on the bottom. That means the overall length of the strut assembly can be adjusted by spinning that center item -- basically a turnbuckle, but for compression, rather than tension. Thus, adjustability is a purpose. I'm curious if there is any vibration or shock attenuation material in there as well. $\endgroup$
    – Tristan
    Feb 4, 2021 at 15:51
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    $\begingroup$ The cross braces are almost certainly primarily for the purpose of reacting lateral loads on that assembly, otherwise it would perform like a four-bar linkage and put enormous stresses on the end fitting plates. $\endgroup$
    – Tristan
    Feb 4, 2021 at 15:52
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    $\begingroup$ Though I can't see enough of the structure to be certain, it appears the entire weight of the tank shelf and the gold-anodized panels underneath it are hanging from the top frame, so those struts would provide all of the compressive load from the bottom plate. $\endgroup$
    – Tristan
    Feb 4, 2021 at 15:55


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