[meteorite-list] Giant Asteroid Fragment Makes Impact

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu May 11 18:25:18 2006
Message-ID: <200605112223.PAA27409_at_zagami.jpl.nasa.gov>

>
> Hi,
>
> The rational for survivor fragments of an impactor is
> that they are from the far back side of the impactor. The
> transformation of the impactor's mass from a solid to a
> plasma proceeds from the "front" or impacting surface.
> A shock wave from this explosive vaporization preceeds
> the actual transformation, traveling at the impact speed
> of the body plus the rate of expansion of the vaporization.
> If this shock wave speed exceeds the speed of sound in
> the impacting body, the shock wave will fracture, pulverize
> and even vaporize (if it's fast enough) the body of the
> impactor ahead of it.

Another possibility is the meteorite fragment they found was from
another fall, and not from the impactor that created the crater.
 
> The models say the transient crater is deep, but it would
> shallow up dramatically from rebound and ends up as
> an extremely shallow crater for its size. If there was
> little shock melting, is it possible that rebound melting
> occured? Or the release of local vulcanism? I don't know
> if we know enough about this crater to be sure.


Bear in mind a lot can happen geologically in 144 million years since
the crater was formed, not to mention erosion effects. The depth
the crater is at today is probably not the depth it was when it was
created.

Ron Baalke
Received on Thu 11 May 2006 06:23:14 PM PDT