[meteorite-list] Terminal burst altitude vs. entry angle

From: Matson, Robert D. <ROBERT.D.MATSON_at_meteoritecentral.com>
Date: Mon, 25 Mar 2013 20:19:22 -0700
Message-ID: <7C640E28081AEE4B952F008D1E913F170743636A_at_0461-its-exmb04.us.saic.com>

Hi Kelly,

> ... what Mike Farmer says agrees with Boslough's assessment: had the
> impactor come in more vertically, its terminal burst would have been
> lower ...

Since the dynamic pressure on the bolide is a function of the square
of its velocity and the atmospheric density, it seems to me that a
steeper entry angle must cause the body to break up at a higher
altitude, not lower. A shallower entry angle allows the meteoroid
more time to bleed off cosmic velocity in the thin upper atmosphere.
With that lower velocity, the dynamic pressure that will cause breakup
of the meteoroid does not occur until a lower altitude is reached
where the atmospheric density is correspondingly higher.

I *did*, however, fail to take into consideration the projected area
aspect of the problem. In the more vertical case, the shockwave is
projected into a smaller area; in essence, there is less volume
available to absorb all that energy. That may be more than enough to
outweigh the slightly higher breakup altitude. --Rob
Received on Mon 25 Mar 2013 11:19:22 PM PDT