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(meteorobs) Fw: DoD Satellite Fireball detection.



    Posted with the kind permission of Dr. Peter Brown.


----- Original Message -----
From: Peter Brown <pbrown@julian.uwodot ca>
Subject: [MIAC-L] DoD fireball detection analysis and possible fall location


> Fireball Detection
>
> IR sensors aboard US  DOD satellites detected the impact of a bolide
> over
> the Eastern US on 23 July 2001 at 22:19:11 UTC.
> The object was traveling roughly East to West.
> The object was first detected at an altitude of approximately 82km at
> 41.5
> North Latitude, 75.6 West Longitude,
> and tracked down to an altitude of approximately 32 km at 41.3 North,
> 77.3 West.
> The impact was simultaneously detected by space based visible wavelength
> sensors
> operated by the US Department of Energy.  The total radiated energy was
> approximately 1.27 X 10^12 joules.
>
> **************************************************************************
>
> PLEASE NOTE THAT THIS SATELLITE BOLIDE RELEASE AND ALL PREVIOUS
>
> SUCH RELEASES CAN BE FOUND ON THE WWW AT
>
> http://phobos.astro.uwodot ca/~pbrown/usaf.html
>
> --
>
>
> To attempt to assist those looking for material from this object,
> the undersigned has computed a set of possible orbits, likely
> initial velocity, inferred mass and range of possible ground
> points for various sized fragments from these DoD data. It is emphasized
>
> these are approximate and preliminary.
>
> Orbit
>
> The satellite derived apparent radiant azimuth is approximately
> 80 degrees and the elevation is 21 degrees. The terminal ground
> projection of the fireball path is a ground distance of 83 km
> from the 32 km altitude position at 41.2N, 78.3W.
> Referenced to this location, the apparent radiant and a range of
>  possible velocities yield the following table of low-precision
> orbital solutions:
>
> Month :     7  Day :     23  Time (UT) :    22.317
> Terminal Ground Point (projected) :
>          Lat :   41.2000 Long :   -78.3000
>
>  at azm   vel   ras     de     sma   ecct   incl  argp  lasn     aph
> per
>  21  80  12.0  302.3   -0.9    1.01  0.167  3.2  281    121.097  1.18
> 0.84318
>  21  80  13.0  295.7    5.1    1.08  0.224  6.0  267    121.097  1.33
> 0.84073
>  21  80  14.0  291.8    8.6    1.17  0.278  8.4  257    121.097  1.49
> 0.84356
>  21  80  15.0  289.1   10.9    1.27  0.333 10.4  251    121.097  1.69
> 0.84652
>  21  80  16.0  287.1   12.5    1.39  0.388 12.2  246    121.097  1.92
> 0.84878
>  21  80  17.0  285.6   13.8    1.53  0.445 13.8  242    121.097  2.21
> 0.85031
>  21  80  18.0  284.5   14.7    1.71  0.502 15.3  239    121.097  2.57
> 0.85123
>  21  80  19.0  283.5   15.5    1.94  0.562 16.7  237    121.097  3.03
> 0.85166
>  21  80  20.0  282.7   16.1    2.25  0.622 17.9  235    121.097  3.66
> 0.85171
>  21  80  21.0  282.1   16.6    2.69  0.684 19.1  233    121.097  4.54
> 0.85149
>  21  80  22.0  281.5   17.0    3.37  0.747 20.2  232    121.097  5.88
> 0.85105
>  21  80  23.0  281.1   17.4    4.51  0.812 21.3  230    121.097  8.18
> 0.85044
>  21  80  24.0  280.7   17.7    6.94  0.878 22.3  229    121.097 13.03
> 0.84971
>  21  80  25.0  280.3   18.0   15.41  0.945 23.2  229    121.097 29.98
> 0.84888
>  21  80  26.0  280.0   18.2  -61.74  1.014 24.1  228    121.097-124.33
> 0.84798
>
>
> Where at is the radiant apparent altitude, azm is the apparent azimuth,
> vel is the initial velocuty in km/s,
> ras is the right ascention of the
> geocentric radiant, de is the declination of the geocentric radiant, sma
> is the semi-major axis of the
> orbit in AU, ecct is the eccentricity, incl is the inclination, lasn is
> the longitude of the ascending node, aph
> is the aphelion distance in AU, per is the perihelion distance in AU.
> All angular elements
> are J2000.0
>
> >From these orbit solutions, the most similarity with previously
> determined meteorite orbits is found for
> initial velocities in the 17-20 km/s range, though lower velocities are
> possible.
> Note that velocities in excess of 22 km/s are unlikely and those in
> excess of 26 km/s are unbounded.
>
> >From the optical energy estimates and assuming a 10% optical conversion
> efficiency to total yield (as has been
> found to be reasonable for several previous events), the total initial
> energy for this bolide would be 1.27x10^13J
> (or 3.0 kT TNT equivalent). For a velocity of 17 km/s this represents an
> initial mass of approximately 90 metric
> tonnes; for 20 km/s it is approximately 30 metric tonnes.
>
> Fragment fall locations.
>
> The uncertainty in initial velocity (as well as velocity at the final
> end point) make estimates
> for the fall locations extremely uncertain. We can say that material
> should be located uprange
> of the terminal ground point (78.3W, 41.2N). Approximate darkflight
> computations (assuming an end velocity at
> 32 km of 12 km/s) give the following ground locations for an ordinary
> chondrite:
>
> Mass (kg)   Lat (N)   Long (W)
> 0.1         41.26     77.48
> 0.3         41.25     77.53
> 1           41.25     77.60
> 7           41.24     77.70
> 10          41.22     77.85
> 150         41.22     77.87
>
>
> This region is part of the Sproul State forest.
>
>
> --
> *********************************************************************
> Dr. Peter Brown
> Los Alamos National Laboratory
> Technical Area - 51, Bld 80
> Group EES-8, Earth and Environmental Sciences Division
> Mail Stop J577
> Los Alamos, New Mexico
> 87545
> USA
>
> ph:505-665-7134
>
> email:pbrown@vega.lanldot gov
>
> fax:505-667-9122
>
> ph:505-820-2480 (H)
> *********************************************************************
>
>

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