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

From: MexicoDoug <mexicodoug_at_meteoritecentral.com>
Date: Sun, 25 Sep 2011 16:32:28 -0400 (EDT)
Message-ID: <8CE49D960BA3F31-1654-983FC_at_webmail-m026.sysops.aol.com>

Hi Stuart, List, Sterling, Kirk and all,

The official statement based on a 9-year old estimate which was
magically updated:

"Estimated human casualty risk (updated to 2011): ~ 1 in 3200"

which I interpret to mean death or injury, though it could be
interpreted as death alone.

NASA/DoD used FPBBNOQ, their version of the risk assessment program to
"determine" this,
(a.k.a. falsely precise black box that no one questions otherwise known
as ORSAT)

NASA's ORSAT calculations were that the impact:

* Cross sectional area 3.49 m^2 of UARS debris
(that's 37.5 square feet)
* 26 pieces surviving
* 532.38 kg mass total impacting weight

 ORSAT, their proverbial magic black box:
"Estimated human casualty risk (updated to 2011): ~ 1 in 3200"

The excuses and justifications and sweet talk (something like we hear
in politics or by the slouchers that promise results at work IMO):

No NASA or USG human casualty reentry risk limits existed when UARS was
designed, built, and launched.
? NASA, the USG, and some foreign space agencies now seek to limit
human casualty risks from reentering space objects to less than 1 in
10,000.
? UARS is a moderate-sized space object. Uncontrolled reentries of
objects more massive than UARS are not frequent, but neither are they
unusual.
     ? Combined Dragon mockup and Falcon 9 second stage reentry in June
2010 was more massive.
? Since the beginning of the space age, there has been no confirmed
report of an injury resulting from reentering space objects.

Read all about it here:
ref:
http://www.nasa.gov/pdf/585584main_UARS_Status.pdf

Kindest wishes
Doug

-----Original Message-----
From: Stuart McDaniel <actionshooting at carolina.rr.com>
To: Meteorite-list <Meteorite-list at meteoritecentral.com>; MexicoDoug
<mexicodoug at aim.com>
Sent: Sun, Sep 25, 2011 3:38 pm
Subject: Re: [meteorite-list] 1 in 3200 odds of human impact (help)


Maybe they were calculating odds in the US only at the 1:3200.



Stuart McDaniel
Lawndale, NC
Secr.,
Cleve. Co. Astronomical Society
IMCA #9052
Member - KCA, KBCA, CDUSA
-----Original Message-----
From: MexicoDoug
Sent: Sunday, September 25, 2011 12:31 AM
To: Meteorite-list at meteoritecentral.com
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 04:32:28 PM PDT