On Sunday, 25 September 2016 12:34:12 PM AEST Robin Humble via luv-main wrote:
> On Fri, Sep 23, 2016 at 01:59:16PM +1000, Russell Coker via luv-main wrote:
> >Is there a good free orbital simulator for Linux?
> >
> >I don't want a game like KSP but a simulation of orbits without much need
> >for fancy graphics.
> >
> >I am wondering what the orbit of a ring would be like (EG a Dyson ring) and
> >whether it's plausible to make such a ring or whether a set of
> >disconnected sattelites in the same orbit is required.
> is there such a thing as a Dyson ring? I thought it was a Niven ring, as
> per Ringworld, Ringworld Engineers etc. and as (fans of) those books
> pointed out, rings are unstable no matter what.

I just made that term up as it seems to accurately describe it.  But the term
Niven Ring was invented first (I've just read the Wikipedia pages about his
books).

> a full Dyson sphere is neutrally/meta stable, but no idea how you'd
> actually construct it in a stable manner... likely someone has thought
> about it though!

https://en.wikipedia.org/wiki/Ringworld

One thing that's noted in the Errors section of the above page is that a
ringworld as a rigid structure is not in orbit around the star but spinning
independently and would need attitude jets to keep it in place.  A full Dyson
sphere would require the same but with greater complexity as the jets could
only be on the outside of the sphere.

> short version is that gravity is a harsh mistress, often chaotic, and
> hard to do right over long timescales. do you think the solar system
> is stable? you are wrong. satellites? nope. but depends upon what
> timescales they drift/resonate.

https://en.wikipedia.org/wiki/Klemperer_rosette

The Klemperer Rosette is also interesting.

> I mostly know about high N N-body codes, but I have a symplectic toy
> low N multi-timestep python code that I wrote somewhere. there are probably
> high performance (giga-year) public symplectic low N codes out there too.
>
> BTW all mine are collisionless. quite different to David Zuccaro's
> (intriguing - asteroid field?) collisional code.

https://en.wikipedia.org/wiki/Alastair_Reynolds

Alastair Reynolds Revelation Space series features a system that had a huge
number of inhabited satellites that all collided after an alien virus
destroyed their computers.  NB this isn't a spoiler as that collapse isn't
covered in his novels.  His novel set before the collapse was published long
after novels set after it which mention it in passing.

--
My Main Blog         http://etbe.coker.com.au/
My Documents Blog    http://doc.coker.com.au/

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