[meteorite-list] Landsat 4 Image Of Meteor Crater

From: meteorites_at_space.com <meteorites_at_meteoritecentral.com>
Date: Thu Apr 22 09:41:10 2004
Message-ID: <20010215144216.22899.cpmta_at_c000.snv.cp.net>

On Wed, 14 February 2001, Ron Baalke wrote:

>
>
> http://photojournal.jpl.nasa.gov/cgi-bin/PIAGenCatalogPage.pl?PIA03212
>
> Image Title:Barringer Meteor Crater, Arizona
> Catalog #:PIA03212
> Target Name:Earth
> Is a satellite of:Sol (our Sun)
> Mission:Landsat
> Spacecraft/Mission:Landsat
>
> Instrument:Unk
> Product Size:439 samples x 593 lines
> Produced By:JPL
> Primary Data Set:Landsat_page
> Full-Res TIFF:PIA03212.tif (890 kbytes)
>
> Original Caption Released with Image:
>
> Barringer Crater, also known as 'Meteor Crater,' is a 1,300-meter (0.8
> mile) diameter, 174-meter (570-feet) deep hole in the flat-lying desert
> sandstones 30 kilometers (18.6 miles) west of Winslow, Arizona. Since
> the 1890s geologic studies here played a leading role in developing an
> understanding of impact processes on the Earth, the moon and elsewhere
> in the solar system.
>
> This view was acquired by the Landsat 4 satellite on December 14, 1982.
> It shows the crater much as a lunar crater might appear through a
> telescope. Morning sun illumination is from the southeast (lower
> right). The prominent gully meandering across the scene is known as
> Canyon Diablo. It drains northward toward the Little Colorado River and
> eventually to the Grand Canyon. The Interstate 40 highway crosses and
> nearly parallels the northern edge of the scene.
>
> The ejecta blanket around the crater appears somewhat lighter than the
> surrounding terrain, perhaps in part due to its altered mineralogic
> content. However, foot traffic at this interesting site may have
> scarred and lightened the terrain too. Also, the roughened surface here
> catches the sunlight on the southerly slopes and protects a highly
> reflective patchy snow cover in shaded northerly slopes, further
> lightening the terrain as viewed from space on this date.
>
> Image Note:
> Image Size: 16.9 km x 12.5 km Colors: Bands 1, 2+4, 3 in blue, green,
> and red, respectively.
>
> ----------------------------------------------------------------------------
>
>
> _______________________________________________
> Meteorite-list mailing list
> Meteorite-list_at_meteoritecentral.com
> http://www.pairlist.net/mailman/listinfo/meteorite-list

The whiteish area surrounding the crater extending to the northeast of the crater corresponds nearly eaxactly to the distribution of shrapnel fragments thought to have spalled off the back of the impactor at the instant of impact.

It is thought that as the meteoroid hit the ground, a shockwave from the front (the point contacting the ground) traveled toward the back of the meteoroid. Then when it reached the back it created a shower of backward traveling red hot fragments. These would account for the large number of jagged heat altered shards found in an area extending about 1 to 2 miles to the northeast of the crater (the area shaded in white in the photo).

But the area was also scoured by Nininger with his truck sporting drag electromagnets. With these, he sort of wore out the carpet with Meteor Crater INC. (they still talk about it), and also gleaned over 50,000 meteorite specimens from the plains close to the crater.

The white area in the photo is also the area where the highest concentration of metallic sphereoids are found. If I recall correctly, Nininger estimated that the concentration close to the crater averaged about 13 tons per square acre!

And with this esitimate, and the approximate area over which they are spread, a weight for the impactor was calculated at over 50,000 and perhaps 100,000 tons, thus confirming previous mathematical estimates of its mass.

Regards,
Steve Schoner

http://www.geocities.com/american_meteorite_survey

___________________________________________________________________
Join the Space Program: Get FREE E-mail at http://www.space.com.
Received on Thu 15 Feb 2001 09:42:16 AM PST