Path: ...!weretis.net!feeder9.news.weretis.net!news.quux.org!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail
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 13:47:50 +0000
Organization: A noiseless patient Spider
Lines: 45
Message-ID: <vqpeuc$20buo$1@dont-email.me>
References: <vq5mv3$1ii40$1@dont-email.me> <vq80l1$22pl6$2@dont-email.me>
 <ic2fsjhuqu06vhjsrassubm79n9r62k9jm@4ax.com> <vq8jtq$299g5$1@dont-email.me>
 <j9sm9l-jus6.ln1@coop.radagast.org> <vqavu4$2m5a5$2@dont-email.me>
 <vren9lx8t.ln2@Telcontar.valinor> <vqb3fj$2mon7$1@dont-email.me>
 <d1fo9lx8ms.ln2@Telcontar.valinor> <vqcje9$323d7$1@dont-email.me>
 <0t33alxpnm.ln2@Telcontar.valinor> <vqmsui$1ck58$1@dont-email.me>
 <fon5alxne9.ln2@Telcontar.valinor> <vqpd77$1vssc$1@dont-email.me>
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Injection-Date: Tue, 11 Mar 2025 14:47:57 +0100 (CET)
Injection-Info: dont-email.me; posting-host="b28b58eca7309331ca614dc54010278d";
	logging-data="2109400"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX1/d8AYK7AGlWiJHDZ5RO6HZil5tuERmgYo2swKsmmse/g=="
User-Agent: Mozilla Thunderbird
Cancel-Lock: sha1:sI9aV7Qf57jwNDvXpOBAfM3apjw=
In-Reply-To: <vqpd77$1vssc$1@dont-email.me>
Content-Language: en-GB
Bytes: 3675

On 11/03/2025 13:18, Bill Sloman wrote:
> On 11/03/2025 11:43 pm, Carlos E.R. wrote:
>> On 2025-03-10 15:28, Bill Sloman wrote:

>>> The historical record - in terms of meteor craters big enough to have 
>>> survived for a few million years - demonstrates that big earth 
>>> grazing asteroids are pretty rare. I imagine that somebody has worked 
>>> out what the distribution is, at least roughly.
>>
>> There is evidence of dangerous "objects" hitting the earth and causing 
>> destruction in the "historic" age.
>>
>> Example: https://en.wikipedia.org/wiki/Tunguska_event
>>
>> We were just fortunate that it hit a non populated area, otherwise it 
>> could have destroyed a city. The explosion was between 3 and 50 megatons.
> 
> You really are a twit. If you had bothered to read all the way through 
> my post, you would have found exactly the same url (so it shows up twice 
> in your post, which is a touch comical).
> 
> And the object didn't explode - it just came apart. Lots of very fast 
> moving, very hot rocks rocks (it does seem to have a stony asteroid, 
> which is presumably why it didn't make all the way down to the ground) 
> would have produced a huge shock wave, so it might as well have 
> exploded, but calling it an explosion implies that the energy emerged 
> suddenly, rather than just coupling into the atmosphere when the air got 
> dense enough to have a significant interaction with the fast moving rock.

The exact dynamics for Tunguska are still a bit unclear but assuming it 
was a typical rock ice composite material then it probably did to a very 
good approximation explode once the hypersonic shockwave from impacting 
the denser atmosphere exceeded the binding forces holding it together. 
Most sources describe it as an explosion at about 6 miles altitude.

https://www.nasa.gov/history/115-years-ago-the-tunguska-asteroid-impact-event/

No pieces of it have ever been identified as reaching the ground.
It is assumed that most of it vapourised.

Finding meteorites is a lot easier in Antarctica than on Arctic tundra.

-- 
Martin Brown