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From: Martin Brown <'''newspam'''@nonad.co.uk>
Newsgroups: sci.electronics.design
Subject: Re: Earth-grazing asteroids as a military resource
Date: Tue, 11 Mar 2025 16:17:26 +0000
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On 11/03/2025 13:34, Bill Sloman wrote:
> On 11/03/2025 9:18 pm, Martin Brown wrote:
>> On 06/03/2025 16:44, Bill Sloman wrote:
>>> On 6/03/2025 10:54 pm, Carlos E.R. wrote:
>>>> On 2025-03-06 04:06, Bill Sloman wrote:
>>>>> On 6/03/2025 1:45 pm, Carlos E.R. wrote:
>>>>>> On 2025-03-06 03:05, Bill Sloman wrote:
>>>>>>> On 6/03/2025 8:28 am, Dave Platt wrote:
>>>>>>>> In article <vq8jtq$299g5$1@dont-email.me>,
>>>>>>>> Bill Sloman  <bill.sloman@ieee.org> wrote:
> 
> <snip>
> 
>> There is a limit to haw far into the future we can predict the 
>> trajectory of a comet or asteroid. It depends how well the orbit has 
>> been determined and how close it gets to any of the other big solar 
>> system bodies. Jupiter serves as a cosmic hoover by slingshot effect 
>> putting things into orbits that typically intersect with it or get 
>> flung much further out. Shoemaker Levy 9 famously suffer that fate
> That insight has been formalised as a claim that the planets' orbits are 
> chaotic over longer time scales, in such a way that the whole Solar 
> System possesses a Lyapunov time in the range of 2~230 million years.
> 
> https://en.wikipedia.org/wiki/Stability_of_the_Solar_System

I think Ovenden's conjecture is probably more likely to be true in the 
sense that although we can't exactly predict things we can put quite 
good bounds on how far out of kilter things can actually get chaos wise 
in the solar system (barring a close encounter with a passing star or 
other seriously massive object shaking things up).

His conjecture is pretty much that the big guys are locked in resonant 
orbital patterns that avoid each other as much as possible. It seems to 
hold equally well for moons of planets as well as planets of suns.

It says nothing about whether or not they could contrive to say eject 
Mars from the solar system entirely. What is known from composition of 
the planets is that they didn't all form exactly where they are now.

-- 
Martin Brown