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From: Don Y <blockedofcourse@foo.invalid>
Newsgroups: sci.electronics.design
Subject: Re: Earth-grazing asteroids as a military resource
Date: Wed, 5 Mar 2025 03:38:34 -0700
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On 3/5/2025 3:02 AM, Martin Brown wrote:
> Timing is everything in orbital dynamics.
> 
> The Earth is moving along it's orbit at 30km/s and the impactor is similar or 
> possibly faster depending on its orbital parameters. IOW just a couple of 
> minutes difference between a direct hit and a miss.
> 
> Its actually better than that since glancing impacts will skim off the upper 
> atmosphere like a stone does off off a pond. And only iron or stone ones coming 
> in at relatively steep angles get to reach the ground. Many are loose 
> aggregates of ice and pebbles that disintegrate on entry.
> 
> Earth also spins at 1000 mph at the equator which further complicates timing if 
> you want to hit an actual specific coordinate on the globe.

A more interesting approach would be to install a mass cannon on the Moon.
The math is considerably simpler and there appears to be plenty of
"surplus rock" to use as the source of mass!  :>