(meteorobs) 2012/02/01 TX Fireball - darkflight results

[Mike Hankey]

Bill,

Thanks very much for doing this. Great work!

Mike Hankey
Freeland MD

On Thu, Feb 9, 2012 at 6:41 PM, Bill Cooke <cookewj at comcast.net> wrote:

> This morning I reversed my earlier position and decided to ask my team to
> perform the necessary calculations to compute an impact zone. This is a 2
> step process - first, each observed fragment of the meteor (only 1 piece in
> this case) has to have its trajectory extrapolated via a single body
> ablation code from the last observed position to the point where it is no
> longer ablating, i.e., when the speed drops below 4 km/s. This position is
> then used as the start point for the darkflight calculations, which take
> the meteor all the way to the ground.
>
> 3 sets of calculations were performed - two of the sets were done by my
> team here at MSFC, with densities of 2.3 (carbonaceous chondrite) and 3.7
> g/cc (ordinary chondrite). We did not take into account the winds, as our
> code is a work in development (we can only handle winds in an average
> sense). However, I also asked the Meteor Physics Group at the University of
> Western Ontario to do a 3rd set of calculations; their numbers do account
> for the wind data and assume a density of 3.7 g/cc.
>
> The results are given in the purple, yellow, and orange columns of this
> table:
>
> http://www.billcooke.org/events/texas_darkflight_2012Feb02.pdf
>
> They are plotted here:
>
> http://www.billcooke.org/events/Darkflight_all.jpg
>
> The masses are not your usual 1g, 10g, 100g, 1 kg sizes. I just took
> whatever came out of the ablation code and ran them through the darkflight.
> Normally we would iterate on the ablation until we got a starting mass at
> the last observed position which would ablate down to one of the standard
> sizes I just mentioned. However, I feel that these adequately characterize
> the lengthy fall area, caused by the shallowness of the meteor trajectory.
> As I expected, this is a lot of territory to cover, and it is quite
> possible meteorite fragments could have landed in the area lakes.
>
> I believe that Mark Fries and Rob Matson have identified some doppler
> signatures that may help the hunters out there. Hopefully something will be
> found soon.
>
> Regards,
> Bill Cooke
> NASA Meteoroid Environment Office
> Marshall Space Flight Center
> Email:william.j.cooke at nasa.gov
> Office: 256 544-9136
>
>
>
>
>
>
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