The Dyson sphere problem

Modelling the dynamics of Dyson spheres in the Solar system. The Dyson sphere and Dyson ring are hypothetical megastructures intended for large-scale capture of solar power.
These simulations test the long-term stability and dynamics of 0.9 AU radius few-node Dyson rings and Dyson spheres with rigid and elastic frame elements.

The conservative dynamics are based on the classical gravity of the eight planets and Sol. The gravity from the nodes (or solar cells) is assumed to be negligible and the frame is assumed to be massless.

Planets radii are visually scaled by 1000 and Sol by 20

0:00 Solar system (2015 Jan. 1 ephemeris, barycentric frame)
0:19 Slow retrograde Dyson sphere
0:58 Stationary Dyson sphere
1:37 Dyson ring
1:49 Dyson sphere with elastic frame
2:32 Fast-forward stationary Dyson sphere (Jupiter's gravitational pull is clearly visible)

The tests show in general that the triangulated icosahedron Dyson sphere diverges from the barycenter within 100 years, and even faster with less rigid frames or when restructuring the megastructure as a Dyson ring, lacking the tangential stability altogether.

The most notable origin of instability on the Dyson sphere is the gravitational pull from Jupiter. The non-zero net force on the Dyson sphere from objects within (Sol in particular) is caused by few nodes as opposed to a fully uniform shell with zero net force in compliance with Gauss' law for gravity.

The simulations were performed using high order explicit symplectic integrators and were rendered in real time.

🎵 "Dead Feelings" by "Carter" | not affiliated with/endorsed by.

[Zymplectic]

With scientists unironically searching for star dimming resulting from alien megastructures, and literature only briefly discussing the lacking stability in the idealized uniform shell and rigid frame case - it's time for a reality check.

[nzuckman]

These just keep getting better and better! 😁

[killsalot]

I think building a dyson sphere out of planet sized beams and solar panels would be a bad idea regardless, surely the beams would be much thinner and longer and the panels much smaller and more frequent

[zuthalsoraniz]

Yes, any realistically practicable "dyson sphere" would in reality need to be a large swarm of free-flying structures, probably statites or at least semi-statites (with a large fraction of their weird compensated by solar radiation pressure) due to most of their mass being large-area solar collectors. And they would probably still need active stabilisation against perturbations, though that might be able to be provided in a propellantless way by steerable solar sail vanes and/or by reacting against the solar magnetic field.

Beyond stability (which might be solvable with a similar approach based on redirection of sunlight to produce reactive thrust), a solid dyson sphere would also have the significant issue of collapsing under its own weight. While that might be prevented along the equator by spinning the structure, preventing collapse along the polar axis would require materials that are far beyond current materials science, unless the sphere has a low enough weight per unit area for solar radiation pressure to support its weight.

[JustACuteDoggo]

realistically if aliens had the tech to build one of these, they could probably travel to a star with no planets...at least that would slow down these effects in the short term

great vid! this and your most recent one are really cool, dropped a sub :D

[theodorostsilikis]

The debris of any accident eventually would pose a threat to the entire structure. All being on the same spherical orbit would create a chain reaction.

[overloader]

what about the part where the solar wind and light pushes onto things? With a sufficiently small one it could be like an air balloon but with sun instead of air inside

[mrtommypickles]

Very cool simulation! May I ask what the mass is of the dyson sphere?

[WavyCats]

It’s true that any solar bodies would disrupt the orbit of the sphere but at that energy level, you could just eject the planets out of orbit, and use corrective thrusters to right the orbit against minute objects

[csx]

I wonder if the energy of a the sun is enough to correct the rotation of the dysonsphere