[AR] Re: asteroid mining (was Re: This is cool.)
- From: Henry Spencer <hspencer@xxxxxxxxxxxxx>
- To: Arocket List <arocket@xxxxxxxxxxxxx>
- Date: Mon, 17 Aug 2020 00:43:16 -0400 (EDT)
On Mon, 17 Aug 2020, Troy Prideaux wrote:
In my lifetime I would have witnessed maybe a dozen events which I (in
my ignorance) suspected were copper based meteors... ...a spectacular
green meteor burning across the sky too fast to be categorised as
terrestrial manufactured space junk burning up on re-entry. So, if these
"meteoroids" aren't copper based, what can they be then?
Boron? Beryllium?
Nickel shows as green, I believe, and is a rather more likely case...
Mind you, <
https://www.amsmeteors.org/fireballs/faqf/> says that copper
has been seen in the spectra of some of the brighter ones.
Note an important issue: meteors and meteorites are different animals.
Radar tracking of ordinary meteors reveals that they are decelerating
*quite* rapidly in thin air. Their density must be exceedingly low --
think dust bunnies, not rock or metal! They're guessed to be loose
collections of cometary dust. There are no known meteorites like that;
they must burn up or disintegrate pretty completely. So they come from a
very different population and may have different compositions.
As they go up the scale in size and brightness, of course, eventually
more-solid objects start to show up.
For that matter, there are probably types of honest-to-god solid bodies
that rarely survive to the ground, or are seldom recognized when they do.
The Tagish Lake fragments were like no meteorite anybody had ever seen
before, soft organic gunk, and might have passed entirely unnoticed if
they hadn't come down on a frozen lake.
Henry
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