[meteorite-list] 1 in 3200 odds of human impact (help)

From: Becky and Kirk <bandk_at_meteoritecentral.com>
Date: Sat, 24 Sep 2011 23:47:29 -0500
Message-ID: <04862F9ADEE54DA3B1029539F688F21F_at_owner55652f88b>

WOW---some pretty good calculations and science there Doug----BRAVO!!
NASA screws up yet again!!

Kirk.....:-)

----- Original Message -----
From: "MexicoDoug" <mexicodoug at aim.com>
To: <Meteorite-list at meteoritecentral.com>
Sent: Saturday, September 24, 2011 11:31 PM
Subject: [meteorite-list] 1 in 3200 odds of human impact (help)


> Hi listers
>
> I'm very suspicious of this widely quoted 1 in 3200 that is being passed
> off as a scientific number by NASA.
>
> Not 1:3000, nor between 1:1000 to 1:10,000: but 1:3200.
>
> This foolishly precise assertation, which if you've read "The Little
> Prince" you immediately suspect it is overstated due to the author's
> calculations 70 years ago there...where a similar calculation is actually
> done ...
>
> Average cross sectional area of a person? (Depends if it is in the morning
> when everyone is praying, I guess, or in the afternoon when everyone is
> running out of work)...let's say:
>
> Cross section per person:18 inches by 18 inches (1.5 x 1.5 sq. feet)
> World population: 6.964 X 10^9 living souls
> World Area: 196,939,900 sq miles
>
> Calculations:
>
> * Cross section per person = 2.5 sq. feet
>
> * current world population occupies 624.3 square miles
> (a wee bit bigger than Guam, and smaller than Singapore)
>
> * people that could fit on Earth's surface: 2,196,000,000,000,000 (2.2
> million X 10^9)
>
> * Fraction of Earth's surface that's "people" = 6.96 / (2,196,000) =
> 0.00000317
> = People occupy *ONLY* 3.2 parts per million (3.2 ppm) of the earth's
> surface
>
> So, saving rounding till the end, each piece of UARS actually has a
> 1/315,457 chance of falling on people (1/0.00000317).
> In rounded numbers, that's about 1:320,000 per fragment ==> 26 fragments
> approximately 1:12,000 chance.
>
> I guess if you are American you need more space than if you are
> Indonesian, and changing it to a 18 inches X 17 inches would change the
> result by 6% ie, if 3200 were right for 18X18 it would now be about
> 1:3000, and that is one of so many assumptions making the 3200 number a
> total joke of fake scientific confidence. If you gave everyone a square
> yard ((91.4 cm)^2) instead, it would be in the 3000 range.
>
> But here are the defficiencies I think of looking at it this way:
>
> * this looks at the whole world vs. the limited satellite trace. A true
> measurement would do a little calculus along the path considering the
> population density and the probability of earlier or later entry which
> could change probabilities by an order of magnitude easily.
>
> * I think what I did would work for 26 darts, but not hunks of significant
> size compared to a person's area unit.
>
> * Finally there is the Sylacauga effect for bouncing material that will
> affect things another factor of 2, 3, 4 who knows...
>
> There must be a half dozen other complicating factors to do this right.
> Does anyone know what has been considered to arrive at the bogusly precise
> 3200-1 odds being fed to us?
>
> Love to hear any improvements on the above model (if you can call it a
> model) which I got the 1:12,000 as a streaming (unverified) starting point
> ...
>
> Kindest wishes
> Doug
>
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Received on Sun 25 Sep 2011 12:47:29 AM PDT