[meteorite-list] Park Forest Strewn Field

[Mark Jackson]

Dear List,

As most of you know, I'm working on a crater-possible area in Southern California. This area, I believe, shows evidence of a complex event characterized by an airbust explosion of a main mass which is "followed in" by what I term as "break up companions"; pieces of the main mass that separated from it PRIOR to the explosion. Any one who has seen the Columbia disaster breakup, or the Peekskill fireball video or any bolide film will recall that such "break up companions" tend to fall behind the main mass as they all continue to push forward along the flight path. This can be for any number of reasons; one can imagine it's a simple matter having to do with the lighter mass vs. atmospheric load of re-entry. Remember going along here that heavier companions will hang closer to the main mass than lighter ones. If one continues to imagine that a main mass and some "break up companions" continue along until suddenly the main mass explodes, then one must consider quite a few
 things:

1.) The main mass will send an explosive shockwave out omnidirectionally from it's centerpoint which is the endpoint of it's velocity vector.

2.) The break up companions following the main mass will meet this shockwave as they travel forward. It's safe to assume, given the effects of gravity and the previously discussed atmospheric loading, that they will meet the shockwave at or below the velocity vector; thus they will be forced down and to both or one side of the velocity vector.

Following these objects to the ground, one can continue to imagine they will fall in an ellipsoid pattern that appears perpendicular to the velocity vector. These objects will fall either to one or both sides (PF all landed to the right or east of the velocity vector); the heavier objects will naturally be closer to the velocity vector (the PF house penetrators) with the lighter pieces further down and away (the Crete impactors).

I suggest then that the Park Forest "reverse strewn field" is suddenly not so reverse after all. It's really a collection of pre-airburst companions spread down and away from the exploding main mass. The main mass was probably vaporized or whatever was left continued on into Lake Michigan.

Kindest Regards,

Mark


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Re: [meteorite-list] Park Forest Strewn Field

[Mark Jackson]

Sonny  List,

So far as I know Sonny, we are struggling to come to terms with this type of strewn field for the first time by hashing it out amongst ourselves. Sterling K. Webb was very close to the mark by pointing to the “pre-airburst breakup companions” but he couldn’t find reason for the extreme NW to SE elongation of the pattern (very good work Sterling!). Some have suggested winds aloft; that is not ruled out at all and should be characterized. I struggle mightily, however, with winds being more than a small factor in the fall pattern of PF. I believe the shockwave has very much more to do with the flattening and elongation of the perpendicular “pre-airburst breakup companion” strewn field; the reason for this is those companions fly right into the shockwave close to it’s peak pressure (right after detonation), and that must affect their flight paths to a large degree.

If it turns out to be accepted, we should call falls like PF “airburst fall fields” because it can only happen when there are companions following into an airburst shockwave. Well, before we do that, there have beena couple ofother strewn fields that match the 90 degree out pattern as pointed out by Ron Baalke and others; I have not read the scientific papers associated with those falls to see what the investigators concluded, so we may be repeating work already done.

To answer some of your other questions, I have no way of telling you what any particular strewn field will look like; they are such dynamic events it would be impossible. There are some basic tenets of physics that will apply however. If you take a line called the velocity vector of the original body and intersect it with the earth, that’s what DoD calls the “straight-line intersection”. In a vacuum, undisturbed by any other forces, the impact point would be right on that point. In a total breakup situation, like Columbia, the heaviest pieces will always be closest to the straight line intersection (the far end of the strewn field). Better put, heaviest objects will always be closest to the velocity vector AND the straight-line intersection because they carry the most kinetic energy and are therefore the hardest objects for outside forces to move off course. 

Something else to remember: these are all pre-impact elements we are discussing here; this is WAY different than discussing a post-impact ejecta pattern.

I have found what I suspect to be meteorite fragments at my crater-possible site. Nothing I have found has yet been confirmed to be of impact or meteoritic origin, however. I am not a PhD or anything I just do this stuff because I like it and I have great interest in it.

Finally I don’t know what a “meteorite recovery team” is . . . but I want to sign up!

Kindest Regards,
Mark
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