[meteorite-list] How much survives entry?

From: Chris Peterson <clp_at_meteoritecentral.com>
Date: Fri, 4 Dec 2009 12:47:36 -0700
Message-ID: <1A31A56AEA234E4583A230333F3D8BF7_at_bellatrix>

I didn't say semantic tweaks don't matter... I only said that their need
depends on how the question is phrased.

The examples you give describe variations in physical conditions, not
semantics. As I also noted in my original post, there has to be a very wide
variation in reality, making it difficult to define "typical".

I don't believe I used the value "99.9%" in my responses. What I said is
that you can probably safely assume that in the majority of cases more than
95% of the original mass is lost.

Carancas is a poor example for just about anything, being a singular event.
However, even that case doesn't seem unreasonable. If we assume the impactor
was 1 ton (about 1 meter diameter), a 95% loss means the parent was 20 tons
(about 2 meter diameter); if we assume a 99% loss, the parent was 100 tons
(about 4 meter diameter). These numbers are perfectly reasonable and
believable. Of course, Carancas almost certainly had less than the usual
amount of ablation because it impacted before ablation had stopped.

Yes, estimates are a kind of guess. But "guess" doesn't have to mean a
random choice. The idea that the parent bodies of most meteorites lost more
than 95% of their mass to ablation is based on solid theory and observation.

Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com


----- Original Message -----
From: <cdtucson at cox.net>
To: "Chris Peterson" <clp at alumni.caltech.edu>; "meteoritelist"
<meteorite-list at meteoritecentral.com>
Sent: Friday, December 04, 2009 12:02 PM
Subject: Re: [meteorite-list] How much survives entry?


> Chris,
> Again, With all due respect.
> How can you say semantic tweaks don't matter?
> Semantics are everything.
> I know he asked about chondrites but they do vary in density.
> What if it is Iron vs, very low density like a CI1?
> What if it is huge vs. tiny?
> What if it is traveling at a super fast speed at a very steep angle?
> It seems TC3 came in at an angle that would argue that there would be very
> material little left. It also is a very porous and fragile material which
> would also lend itself to quick destruction entering our atmosphere.
> According to the show there was two different materials found. So, this
> meteoroid was made up of different materials which would contribute to
> break-up vs, holding itself together.
> Simple Examples here; as Sterling said without math.
> What if you put an iron meteorite into a rock tumbler. And then you put a
> CI1 into a similar rock tumbler. The amount of time it would require for
> these different rocks to end up as dust would be quite significant,
> wouldn't it? And given there is a very small time table for the ablation
> process to occur it seems obvious that the time spent in the ablation
> process alone would be sufficient to prove that the density of the
> meteoroid matters a lot.
> Secondly, The size of the material has a lot to do with ablation. Also
> based on time in ablation zone of the atmosphere.
> Using the same scenario, if you put say a marble size piece of meteorite
> along with a baseball size piece of the same meteorite. The marble size
> will have ablated to 100% dust far before the larger piece. Simple logic
> here.
> Please tell me how this example does not argue that it is in fact possible
> for a very high percentage of the material to survive.
> Lets say it's a mile wide iron traveling super fast at a 90 degree angle
> (which would get it through the ablation zone very quickly). It seems that
> it is very possible for most of it to survive.
> Based on your 99.9% guess. that would mean that Carancas would have
> entered our atmosphere the size of a small planet. We recovered aprox. 10
> kilos and guesstimates are that most of it was lost to the crater. So, if
> you take whatever the guess is for the size that hit the ground and
> multiply it by 99.9% that means it would have been possibly miles wide. If
> it was I am surprised nobody saw it coming. Even with this highly studied
> event. The scientists are still arguing about the speed. One says it came
> in very fast while another says it came in very slow. Either way it seems
> to me the size estimate would also vary.
> So, isn't any estimate a mere guess at best? Thanks Carl
> --
> Carl or Debbie Esparza
Received on Fri 04 Dec 2009 02:47:36 PM PST