I'm familiar with various proposed configurations for generating spin gravity from the Von Braun wheel, O'Neil cylinder, Bernal Sphere, the hamster wheel centrifuge of 2001's Discovery ship, the various large 'whole ship' spinning drums etc.

However, in online materials I've seen mention and semi technical proposals for a relatively small compartment spinning at the end of a counterweighted boom. A great example of the concept comes from the Sci Fi show The Expanse the ship Edward Israel shown in the image here.

My question is: Is there a recognized name or descriptor for this type of ship/gravity configuration?

enter image description here

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    $\begingroup$ In my book I just call them line and anchors. I know its not a real answer but in common use it makes sense. $\endgroup$
    – Grant
    Jan 12, 2023 at 5:35
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    $\begingroup$ Have a look at projectrho.com/public_html/rocket/artificialgrav.php - quite a few concepts would overlap the pictured version here. Dumb bell, bola, etc $\endgroup$ Jan 12, 2023 at 16:35
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    $\begingroup$ @blobbymcblobby OMG!!! so much at Atomic Rockets that my head is almost literally spinning! Loved image of repair worker spun off from outside of spinning drum. Looking inside his helmet is seen the guy of 'The Scream' painting (Edvard Munch) $\endgroup$
    – BradV
    Jan 12, 2023 at 17:24
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    $\begingroup$ Ha! yes! Its a great site, lots of humor throughout! $\endgroup$ Jan 12, 2023 at 17:52
  • $\begingroup$ I've seen tether-type ones with cables leading to the spinning module, as well as fixed ones relying on relatively solid beams instead. not sure what it's called though, not like it's gonna be a particularly widely-searched google topic! Perhaps "Counterweight Arm Centrifuge?". Also, the shot from The Expanse is quite notable for it having a larger, heavier counterweight closer to the axle, and a smaller, lighter one on a longer arm (in the foreground). This is, I would think, to simulate, say, lunar gravity at the close one, and earth 1G at the long one? $\endgroup$ Jan 13, 2023 at 6:23

1 Answer 1



The closest would be a variation of the dumbbell idea. It is, much like the other common concepts, not new.

I have not seen this particular ship in this particular show but can assume that the boom parts extend outwards once artificial gravity is required, with the crew section further out to benefit from the effect, and the counterweight with no such requirement has the greater mass and does not need to extend as far. Assuming the counterweight is stores, as these deplete they would either have to add things to maintain the mass or adjust the spin speed.

Based on most concepts that I've seen, and on this page that has a great many examples http://www.projectrho.com/public_html/rocket/artificialgrav.php

General idea being crewed section at one end, equivalent section and/or equivalent mass at the other, spin section at the middle connecting to the rest of the ship.

From the above site, we have this from Martin Marietta:

enter image description here

Related concept is the tethered dumbbell or bola:

enter image description here

See also related concept, this paper proposes a dumbbell at the Earth-Moon Lagrange L5 (or L4) point.


enter image description here



This is a very popular concept though, so there are a great many papers, videos, and pages to look at, too many to list here. Having said that, the Atomic Rockets site I linked first is a good place to see such concepts looked at both seriously and in science fiction.


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