[meteorite-list] Feedback: try this specific crater "R5" inArgentina: Darren Garrison: Rich Murray 2009.10.15

From: Rich Murray <rmforall_at_meteoritecentral.com>
Date: Fri, 16 Oct 2009 22:15:12 -0600
Message-ID: <4D555F0338D54DE58265AC99ACDC594F_at_ownerPC>

Hi Darren,

I happened to have spent a lot of time
last Saturday Oct. 10
on calculating the kinetic energy density
of a 10-km wide ice comet at 5 km/sec
with density 1.1000 kg per cubic meter
(which includes 0.100 kg per cubic meter for any dissolved solids).

http://www.lpl.arizona.edu/impacteffects/
Earth Impact Effects Program

I got the same number as their program, for a vertical impact.

"Energy before atmospheric entry:
7.20 x 10E21 Joules = 1.72 x 10E6 MegaTons TNT"

The total mass turns out to be 5.76x10E14 kg,
so the energy density is 1.25x10E7 J/kg

One MT is 4.2x10E15 J, so this becomes 3x10E-9 MT/kg,
which is 3x10E-3 tons TNT,
so for 1 ton = about 1000 kg, we get
1 kg TNT per kg comet

So, this is enough to vaporize the ice,
separating all the molecules,
making a high-pressure, high-temperature steam explosion
that would disrupt the surface of the rock impacted,
with cracking, blasting, melting, and vaporizing.

Smashing up water or ice into visible fragments
only takes enough energy to separate the molecules
at the boundaries of the connecting surfaces of the
fragments -- so far less energy,
even with a dramatic shattering of the meteor and the target.

"Transient Crater Diameter: 29.9 km = 18.6 miles
Transient Crater Depth: 10.6 km = 6.56 miles

Final Crater Diameter: 46.7 km = 29 miles
Final Crater Depth: 0.941 km = 0.585 miles

The crater formed is a complex crater.
At this impact velocity (< 12 km/s),
little shock melting of the target occurs.
[ Note: "little shock melting" ]

Ejecta: What does this mean?
Your position [ 10 km from the center ]
was inside the transient crater and ejected upon impact"

Just to make a simple estimate,
I imagined the meteor had 6 stages
of breakup, making 10 more fragments at each state,
so the total number of fragments would be 10E6 = 1,000,000
so each fragment at the same speed would carry energy
1.72 MT per fragment.

If they hit the whole surface of Earth evenly, then
the area of Earth = 5.1x10E8 per square kilometer
would get impact energy 3.3x10E-3 MT
on each square kilometer
= 3.3x10E KT, about 24.4% of the Hiroshima bomb,
which was about 13.5 KT.

So, every area of four square kilometers would get
one Hiroshima bomb of energy -- radiated into space,
heated air during the fall, radiant heat on the Earth,
and local blast effects.

Complex problems = how many big ice fragments?
Distribution of sizes, velocities, locations, angles of
inpact, global and orbital trajectories?
Ice, water, and superhot superdense steam objects or streams?
Air bursts and ground bursts?
Targets of water, ice, soil, rock, inflamable plants?

So, it is reasonable to go poking around all Earth land
surfaces with Google Map and Earth,
looking for complex fields of shallow impacts
with little melting or vaporization, but with
local water flows and some massive regional floods
from condensed steam, melted ice, rain,
new springs in shattered rock,
water ejecta from lakes and seas and damp soils,
tsunamis on coasts, along with widespread fires,
and mostly white minerals
(silicon dioxide, salt, calcium sulfate,
calcium carbonate, grey hematite, red iron
compounds, black manganese dioxide, and
perhaps boron compounds -- ie "Carolina Bays").

http://www.youtube.com/watch?v=QfDoQwIAaXg&feature=player_embedded

Thanks for the great 10 minute slow-motion bullet impact video.
Most of the time the long steel bullets would maintain their
integrity while passing through metal about 1-3 times their own
diameter thick, often with their surface peeled back like
a flower openning around the impact, while the target metal
would flow and splash as a liquid.
The holes were just a little wider than the bullet.

Oblique impacts produced a variety of features, like
ones I've seen often with Google Earth.

http://www.youtube.com/watch?v=emP5D9Klssg&NR=1

This 1 minute video shows when a bullet hits a
standing tomato capsup bottle, as much as about
a third of the explosion is backwards, compared
with the explosion forwards around the bullet.

I've often seen these backwards trenches on
low angle impacts, and assumed they were from
the gradually increasing degree of contact between
meteor and target surface. Of course, the
forwards ejecta, or "pawprints", can be largely
one, two, or many lobes, sometimes, it appears,
with gradually slowing surface water flows,
which can result in ridges or low hills.

Often the one side or the other of the impact
is deeper -- might be from spin around the
forward velocity axis of the meteor.

Rich Murray 505-501-2298 rmforall at comcast.net

----- Original Message -----
From: "Darren Garrison" <cynapse at charter.net>
To: <meteorite-list at meteoritecentral.com>
Sent: Friday, October 16, 2009 9:47 AM
Subject: Re: [meteorite-list] Feedback: try this specific crater "R5"
inArgentina: Darren Garrison: Rich Murray 2009.10.15


> On Thu, 15 Oct 2009 23:46:59 -0600, you wrote:
>
>>Briefly, Carolina Bays (bays mean a particular type of tree in
>>North and South Carolina) are in the range 0.1 to 20 km,
>>probably ice or slushy comet fragment impacts at low
>>velocity ( 5 km/sec )
>
> 5 km/sec is anything but low velocity. The fastest velocity listed on
> this
> chart of military ammunitions is 4000 feet/sec (at 78 feet from the
> muzzle, but
> initial velocity is probably not too far off from that) which is around
> 1.2
> km/sec. 5 km/sec is 4 times faster than a speeding, armor piercing
> bullet. Any
> object traveling anywhere close to 5 km/sec (wherther composed of rock,
> ice, or
> pure crystallized aspartame) is going to make what is known in technical
> terms
> as a "giant-ass" explosion, excavating a deep, round crater.
>
> Here's an amazing bit of video that I've been itching for an excuse to
> post:
>
> http://www.youtube.com/watch?v=QfDoQwIAaXg&feature=player_embedded
> ______________________________________________
> http://www.meteoritecentral.com
> Meteorite-list mailing list
> Meteorite-list at meteoritecentral.com
> http://six.pairlist.net/mailman/listinfo/meteorite-list
>
Received on Sat 17 Oct 2009 12:15:12 AM PDT