[meteorite-list] DoD Satellites Detect March 2003 Bolide Over Park Forest

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:21:04 2004
Message-ID: <200307141720.KAA26001_at_zagami.jpl.nasa.gov>

I wrote:
>>It may be an observing effect depending on whether
>>the fireball was observed from north or south its flight path.

>>Note that the DOD satellite measured the flight path angle at 62 degrees from
>>the horizontal, or 28 degrees from the vertical. That means the meteorite fall
>>was more vertical than horizontal. I think this somewhat vertical flight path
>>may have made judging the flight direction
>>more difficult from the ground, maybe creating an optical illusion effect. It is already
>>well-documented the difficulty in judging the distance to fireballs from a single
>>location. Even if the true flight path was SW to NE as the DOD data indicates, and this
>>would extend the strewnfield out to a larger size along the flight path direction,
>>the near-vertical drop does constrain the size of the strewnfield ellipse.

>>I'm very heavily inclined to believe the DOD satellite measurements are more accurate than
>>the ground observations anyway, because the satellite was designed to accurately
>>record these type of details.

Bob Matson replies:
> I think I can lay to rest any concerns that there was a mistake
> in the DoD report -- the bolide did indeed travel from SSW to
> NNE, and far from contradicting the eyewitness accounts, it is
> in complete agreement with them. You see, with a trajectory
> this steep coupled with the lack of range information (observers
> on the ground can really only measure "apparent" bearing), it
> is not possible to accurately determine the true bearing from
> one observer's viewpoint. For observers south of Chicago, the
> trajectory defined by the DoD report will indeed result in a
> meteor that appears to be headed almost due northwest. To see
> for yourselves, download the following .GIF file that I generated
> with my SkyMap program:
>
> http://members.cox.net/mojave_meteorites/pftrack.gif
>
> The bottom line is that despite the
> 22.5 deg (NNE) true heading, the bolide appears to be heading
> toward azimuth 315, which is due northwest.

Thanks for the plot! I kind of suspected it may have been
an observing effect. Bob Verish pointed out to me that in another
eyewitness case (not Park Forest), a fireball was observed to
be travelling 'up'. This can happen with the right viewing perspective with
a low-angle flight path, even though the fireball is really falling down.

Again, the DOD data indicates the strewnfield is
larger then originally thought, particularly along the true flight path.
I think most of the obvious fragments have been recovered, but people
should now be looking in the less obvious or less accessible areas (ie:
private country clubs). For instance, some of the pieces may have fallen in
soft ground and may be buried, or in areas where there is more vegetation.

Ron Baalke
Received on Mon 14 Jul 2003 01:20:01 PM PDT