[meteorite-list] PROPOSAL: THE CARANCAS CRATER PERU documentation: camera stereo-pair aerial photography FRM: Dirk Ross...Tokyo

[drtanuki]

---note: addresses of sent-to stripped (attached to
bottom of this posting)----resending to metlist (was
sent to Peruvian, US, Canadian, and Chilean impact
specialists and metlist (metlist bounce)-SORRY!


> Dear DRs., Sterling, and List Members,
> 
>  I apologize in advance for mailing several of you
> DRs. a message in a public forum, but this is the
> most
> feasible means to expediently accomplish this
> request
> (some of you may be unaware of the context of this
> post; we are trying to document the recent impact
> crater in Carancas, Peru prior to its "natural"
> destruction and request your kind assistance; thank
> you).
>   For the Honorable Doctors from Peru I apologize
> that
> this is written in English and not in Spanish; I
> cannot write in Spanish.
> 
>   Helium balloon(s) might be the easiest and most
> practical, unless someone has access to an airplane
> or
> jet aircraft.
> 
>   B/W, B/W or Color IR (don`t forget to add an IR
> filter to the camera if an amateur attempts), Color,
> or all of them for filming of stereo-pairs?
> 
>   Anyone have friends with private, commercial or
> military aircraft access in the area?  Any chance
> that
> a military, NASA,  European satellite will be
> crossing
> the area and multi-spectral imagery can be obtained?
> 
> 
>   I have worked with tripod poles and camera for
> such,
> but the size of the area eliminates this
> possibility.
> 
>   If anyone has connections with potential persons
> or
> groups to accomplish this task it will certainly
> help
> in documenting the crater before further damage by
> humans, rain and wind.
> 
>   Hopefully, this can done by a professional.  An
> amateur is more than likely to fail.
> 
>  Thank you all in advance for helping in
> accomplishing
> this task.
> 
>  Comments appreciated and most welcome. Please
> comment
> on this list or privately.
> 
> Sincerely, Dirk Ross...Tokyo
> 
> PS Thank you Sterling for your valuable comments.
> 
>
------------------------------------------------------
> > List,
> > >   The Carancas crater needs to be photographed
> > from
> > > the air with a high resolution camera and a
> > > stereo-pair should also be made.
> > >   Secondly, if the crater is to survive any rain
> > > thought should be given as to how it could be
> > > preserved, with low tech and cost in mind.
> > >   Are their any plastics or cement compounds
> that
> > > could be sprayed over the crater that would
> work?
> > Or
> > > should a plastic cast of it be made to at least
> > have
> > > a
> > > full-sized replica?  If Peru wants a National
> > > Landmark
> > > and tourism to the site they need to take some
> > kind
> > > of
> > > urgent action so that they have more to show
> than
> > a
> > > mud hole full of trash.
> > >   Any thoughts or ideas?
> 
>
------------------------------------------------------"Dr.
Sterling K. Webb" <sterling_k_webb at sbcglobal.net>,
meteorite-list at meteoritecentral.com, "Dr. Ron Baalke"
<baalke at zagami.jpl.nasa.gov>, "Dr. Jeff Grossman"
<jgrossman at usgs.gov>, "Dr. Ronald Woodman"
<ronw at geo.igp.gob.pe>, "Dr. Jose Machare"
<jmachare at ingemmet.gob.pe>, "Dr. Luisa Macedo"
<lmacedo at ingemmet.gob.pe>, "Dr. Peter Schultz"
<peter_schultz at brown.edu>, "Dr. James Whitehead"
<jwhitehe at unb.ca>, "Dr. Jan Cannon"
<craterman1 at aol.com>, "Paul Heinrich"
<heinric at lsu.edu>, "Dr. Harold Connolley"
<meteorite at kbcc.cuny.edu>,  "Dr. Enrique Stucken"
<enriquestucken at yahoo.com>, "Dr. Rob Matson"
<mojave_meteorites at cox.net>, "dirk ross"
<drtanuki at gmail.com>
> 
>---------------------------------------------------- 
> "Sterling K. Webb" <sterling_k_webb at sbcglobal.net>
> wrote:
> Hi, List
> 
> Dirk's suggestion of close aerial stereo pairs is
> the
> best suggestion in a while. It would not only permit
> measurements of the crater but it would map the 
> ejecta blanket, the symmetry (or asymmetry) of 
> which is an important datum.
> 
> The impact excavated about 350+ cu. meters of soil
> and
> 
> rock, weighing about 500-600 tons, of which about 
> 25 cu. meters or 40 tons is to be found in the rim. 
> The ejecta blanket extends up to 200 meters from 
> the crater and covers roughly 125,000 sq. meters. If
> the impact had a low angle, the ejecta blanket would
> be asymmetric, but we don't know because nobody...
> etc., etc.
> 
> I noticed that the pictures of the crater Graham
> posted
> (and which were taken soon after the event, I
> presume)
> a number of good-sized rocks showing whitish patches
> 
> lying on the near ejecta blanket. In Mike's pictures
> of 
> the crater from the same angle, taken days later,
> the 
> ejecta blanket looks the same, but all those
> "white-patch"
> rocks are gone. So, there were some multi-kilo
> stones,
> 
> 6 to 8 at the least, that were collected.
> 
> The north portion of the rim is higher than the
> south
> portion; the impactor came from the north. The slope
> of the crater wall on the south is less than on the
> north;
> this argues a steep angle of impact for the object
> (>60 
> degrees), which means that it came more or less from
> 
> the "top" of the sky.
> 
> The time of the impact was shortly before noon, the
> time when the other object in the "top" of the sky
> was
> the Sun. Now, an object can graze the top of the
> Earth's
> atmosphere at a wide range of initial angles and end
> in
> a downward path steeper than its encounter path.
> That's
> pretty much the way it works. But a very steep
> downward
> path can only result from a fairly steep angle of
> approach.
> 
> This would suggest that the object was approaching
> the
> Earth from the sunward side at altitude of 60
> degrees
> or more.
> Very likely, its initial encounter velocity was
> high,
> given the
> characteristics of such an orbit, if it was
> eccentric
> enough
> to be a Main Belt object (which most
> orbit-determined
> meteorites turn out to be).
> 
> In that case, the question of fragmentation or
> episodes of
> multiple and progressive fragmentation is not as
> relevant as
> it might be. The lateral dispersion velocity of the
> fragments
> is very slow compared to the high speed of the
> object
> (now
> the cluster) and fragments have very little time to
> disperse.
> 
> We have all seen fireball videos in which
> fragmentation
> takes place. Even in prolonged flight, the separate
> fragments
> are seen to be moving in virtually the same path at
> slightly
> different velocities (because of their differential
> drag values).
> In a high speed, very high angle impact, whether
> it's
> one
> huge chunk or 1000 individual pieces hardly matters
> to
> the
> result if they are closely, even intimately,
> clustered. The
> crater could have been made by a very tight cluster,
> but
> only a very tight cluster. 
> 
> The size and persistence of the smoke trail suggests
> that
> ablation was proceeding at a rapid rate, with great
> loss of
> mass; this probably produced a high rate of
> deceleration.
> To be seen easily, noticeably, head-turningly at
> noon
> means
> it must have been very bright indeed.
> 
> We have many reports of the fireball from
> Desaquadero,
> 
> 20 km.* NNE, on the shore of Lake Titicaca. It would
> be 
> a big help if someone could determine if there were
> any
> sightings from locations further NNE, like Tiquina.
> The
> absence of sightings 50 or 100 km. away would
> indicate
> 
> a steep descent; finding more distant reports would
> indicate 
> a shallower descent. It would help rough in the
> geometry 
> of the fall.
> [* The INGEMMET report says 20 km. from Carancas to
> Desaguadero. The map says 10.8 km. The distance of 
> Carancas from the crater has been given as 1200
> meters
> 
> up to 5000 meters.]
> 
> But I now have a reason to believe it is more likely
> to 
> have been a single (surviving) object than a
> fragmenter.
> 
> Rob noticed Doug and I playing one-on-one
> volleyball. 
> Our respective uniforms, his "Slow Impact" jersey
> and 
> my "Fast Impact" jersey, were provided by local
> merchants
> trying to keep us off the street. It's a good thing
> it
> was a
> one-on-one game, because everybody's on the "Slow
> Impact" Team because we get More Meteorite that way.
> 
> The point is well taken that the best way to get a
> meteoroid
> to make that difficult personal transition to a
> meteorite is to
> slow down, sneak up on the Earth's atmosphere
> sidewise,
> and to be as frisbee-shaped as possible. I've made
> that point
> on the List many times before: low entry speed, low
> angle of
> approach, and an aerodynamic shape.
> 
> But here we have a different problem. I see every
> sign
> that
> this was a fast impact, to the annoyance (I'm sure)
> of
> those 
> who want More Meteorite or a big Jilin clone in the
> mudpit. 
> So, how do we get a fast object to the ground
> without
> it
> burning up in the process?
> 
> We change its shape. We are taught (I was) to
> generalize
> to an abstraction. Ask a physicist to model anything
> and
> the first thing he will do is "consider the object
> as
> a sphere
> of radius N." (Look at Chris Peterson's email to
> Mike
> on 
> 10/02/07; there's a man too wise to waste time
> playing
> 
> volleyball with imaginary balls and an invisible
> net.)
> What 
> if the object ISN'T a sphere?
> 
> I've seen lots of pictures of very small asteroids
> and
> none of them
> were spheres: bent peanuts, dumbbells, pancakes with
> dome-poles,
> and something vaguely the size and shape of a
> stripmall-in-space,
> but not one sphere. The smaller the object, the more
> irregular.
> 
> What if the meteoroid was roughly a cylinder 4-5
> times
> longer
> than wide? How would it fare hitting the atmosphere
> at
> 60
> degrees tangent to the ground and 17,000 meters a
> second?
> Well, it depends on its weight, almost entirely, as
> it
> turns out.
> One ton just barely gets to ground at a few hundred
> miles per
> hour and ten tons bores in at 8600 meters per
> second,
> intermediate
> weights at all intermediate speeds, any speed you
> want. None of
> them ablate away completely and none of them
> fragment.
> They
> all make a crater.
> 
> What a remarkable result!
> 
> Back in February '07, when we were talking about a
> new
> and
> big Holbrook find, I posted this reference which has
> an 
> analysis of that strewnfield, asserting that it was
> the product
> of a multiple fragmentation. It uses composite
> scaling
> analysis 
> to model strewnfields, and in so doing the authors
> discover that 
> the original SHAPE of the meteoroid has a much
> stronger influence 
> on the descent to Earth than we realized, may in
> fact
> be the big
> determining factor in what gets to ground and how
> fast
> or 
> slow it does it.
> 
> The link was publicly accessible then, but is now
> only
> 
> accessible to those with big bulgy pockets or
> members
> of The Institutional Academic Scholars Union Local.
> We
> 
> must keep our arcane knowledge out of the hands of
> poor 
> people; it is our duty as a civilization, eh, what?
> (Sorry; 
> I get this way when I Google too much...)
>
http://www.iop.org/EJ/article/0295-5075/43/5/598/node4.html
> L. Oddershede, A. Meibom, J. Bohr: Scaling analysis
> of
> meteorite 
> shower mass distributions. EUROPHYSICS LETTERS,
> 1998, 
> Vol.43, No.5, pp.598-604
> 
> Turns out the only way you can get the original mass
> of 
> the Sikhote-Alin object to the ground is to make it,
> too, a
> long shape, ratio 3:1 or more. A chip off some
> bigger
> block.
> 
> The link that Mike just posted to the List:
> http://home.comcast.net/~C_Shipbaugh/Impact.html
> are calculations by a nanotechnologist who has
> obviously
> never analyzed a meteorite fall before and manages
> to
> get it amazingly right (physics is physics, you
> know).
> He
> does silly things like over-estimating the volume of
> the crater
> by a factor of two because he does not know it's
> conical! 
> Doha!
> 
> He arrives at a 5 ton TNT impact without apparently
> knowing
> that the seismic signal was rated at 5 tons of TNT.
> He, too,
> thinks it was a slow impact, which is why he favors
> 10
> or
> 20 ton objects, but says 4.5 tons at 3000 m/sec is
> most likely
> guess (which is the same as 1.125 ton at 6000
> m/sec).
> 
> He introduces the factor of shape in the form of the
> "ballistic
> parameter or coefficient," but then goes ahead and
> models it 
> as a SPHERE. See, all physicists think alike (well,
> most).
> 
> You are probably saying about now, what is this all
> about?
> Well, remember the glory days of starting into space
> and how,
> after envisioning spaceships all our Buck Rogers
> life,
> we were
> amazed to see the first spaceship, the Mercury
> capsule, was
> an Ice Cream Cone?
> 
> It re-entered on its butt, er, blunt, end for
> maximum
> resistance.
> The re-entry end was a segment of a sphere (probably
> so the
> physicists could model it better). And everyday dumb
> people 
> said, "Why don't they come back with the pointy end
> down; 
> wouldn't that be faster? Better yet, why isn't it
> all
> sleek and 
> thin like a jet plane?"
> 
> Well, we know the answer to that one, of course.
> Because a long
> cylindrical object with an (ablated) point would
> bore
> into the ground
> at tremendous speed. That's the ballistic parameter.
> We wanted the
> Mercury capsule to SLOW DOWN. If we wanted it to
> make
> a big
> crater, it would have looked like the Bell X-1
> without
> wings.
> 
> All it takes to get any meteoroid to the ground at a
> high speed 
> is to stop imagining that God made all the billions
> of
> little rocks 
> in space perfect spheres to make life easy for
> physicists. He likes us... 
> But not that much.
> 
> 
> Sterling K. Webb
> 
> 
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