[meteorite-list] let me just share this graph

[mexicodoug]

Hi Herman,

Glad it could be helpful,  and also would like to thank your for the always 
positive comments and attitude you have on the list.

I prefer the graph I already posted, but I got a private email that it was a 
nice graph, but...but one had to stand on their head to read it best.  So 
here is another version to save anyone from breaking their neck:

http://www.diogenite.com/Huanocollo2.gif

The original, which I prefer, is at http://www.diogenite.com/Huanocollo.gif

Let me try to give a little meaning to the graph in case there are any 
casual readers interested.  As mentioned the graph is specific to the 
latitude of the new Peruvian fall in October, though quite reasonable as an 
estimate in most other circumstances for many latitudes.  It simply shows 
the fraction of the mass of the atmosphere above (or between if you like) 
any altitude between sea level and 25 kilometers height.  The total mass of 
the atmosphere is considered by considering all the mass up to 100 
kilometers altitude.

So, by looking at the graph, you can see that 63.7% of the atmospheric mass 
is above 3.8 Km, the altitude of the new fall.  Actually on the graph it is 
closer to 64%, as the elevation I used was from the Bolivian report which is 
a little less than the 3.8 Km, in case anyone was wondering. (Note to 
Sterling, the 62.1% I quoted before was actually didn't include the value of 
the mass in the interval from 3.8Km to 4.0Km going upward due to a little 
careless arithmetic on my part, so there is a minor bit more atmosphere to 
go through to get to the 37XX meters of the fall elevation..)

Alternately, by looking at the graph, you could determine that:
between 15Km (12.9% atmosphere mass above) and 20Km (5.6% atmosphere mass 
above) altitude, i.e., there is 7.3% of the atmosphere mass, and above that 
only 5.6%.  This is of special interest to meteoritists, as those are the 
typical altitudes given for bolides when ablation ceases usually at 3Km per 
second fall speed (plus of minus 1 Km/s). For a meteorite(oid) not to enter 
free fall velocity, i.e., maintain a non-trivial portion of its cosmic 
velocity, a vertical descent, entering at an angle like Peru's, a vertical 
fall (and this was not vertical, causing the requirement to be higher) would 
have to be something over 5 tons of basically surviving material.  There is 
one unknown, though, and that is relative velocity the meteoroid had with 
Earth, though one would expect it to have been fairly low in order to reach 
the ground.

Finally, the free fall velocity or a sphere that weighs 2 tons at the air 
density (same used to make the graph) is between 0.345 Km/s to 0.385 Km/s. 
That is slightly above the speed of sound which over there is about 0.325 
Km/s.  So we are at least 6% above Mach 1 in free fall for a two metric ton 
sphere of denisty 3800 kg/m^3.  That would be a nice baseline for some 
scenarios as data is released.

For the impact to have been subsonic, for a sphere of that density, the main 
mass would definitely have to weigh less than 1.4 metric tons when it 
impacted (assuming a sphere: orientation can half or double this value). 
That is less than one ton of TNT (popular way to measure explosions), the 
crater looks like it could be as much as a 2-ton TNT size or so but better 
an more bellical person comment on this.  That would require an impactor 
weighing in the 5 to 25 metric ton range, traveling over 0.6 Km/s, but I see 
I am getting into something Sterling might want to comment on.

Hope this sets set some more bases for thought...it is not intended to limit 
scenarios, though.  Hope I've not made any mistakes as I am in sort of a 
rush since today is Monze Day.

Best health, Doug




----- Original Message ----- 
From: <Metorman46 at aol.com>
To: <meteorite-list at meteoritecentral.com>
Sent: Friday, October 05, 2007 12:35 PM
Subject: [meteorite-list] let me just share this graph


>
> Thanks Doug;
>
>  This graph is very useful for future reference.Great job thanks for
> sharing.There is some very informative posts coming out of the carancas 
> fall.What
> an event!Record breaking probably."Meteoritically speaking".Thanks to  all
> posters on this event and the calculations involved.
>
> Best Regards;Herman Archer IMCA # 2770
>
>
>
>
>
>
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