[meteorite-list] getting oriented on orientation

[Darryl Pitt]

mmhhmm...

quick stab

as a result of a lack of tumbling and corkscrewing through the  
atmosphere (the result of the object's mass, distribution of mass and  
angle of entry), the object maintains a somewhat stable horizontal  
and vertical axis during its plunge through the atmosphere, resulting  
markedly different characterics on its obverse and reverse.



On Mar 5, 2008, at 9:52 AM, dave at fallingrocks.com wrote:


> Darryl & List,

> I'd add a point for consideration, and that is the question "what  

> are we talking about when we say a meteorite is oriented?"  By this  

> I mean that, at least from one perspective, the fundamental  

> definition of an oriented meteorite is that it made it's violent  

> passage through out atmosphere in a fixed (non-tumbling) position.   

> As I mentioned somewhere in the series of yesterdays discussion on  

> orientation, we're talking a few second of flight in the "shaping  

> environment" (i.e. the atomsphere).  "Perfect orientation" is often  

> taken to mean that a perfect nose cone with a flat trailing face  

> was created in the process.  But it could also be taken to mean  

> that the meteoroid never tumbled at all, and the original shape of  

> the object as well as its composition, it often seems, has a  

> significant impact on the resultant shape (in other words, in  

> flight the meteoroid was "perfectly oriented" but perhaps the  

> resultant shape is not "perfect").  It is a great thing that you've  

> started this process by virtue of yesterday's dialogue, and  

> hopefully we can emerge with something quantifiable through the  

> process...

> Thanks,

> Dave

>

> -------- Original Message --------

> Subject: [meteorite-list] getting oriented on orientation

> From: Darryl Pitt <darryl at dof3.com>

> Date: Wed, March 05, 2008 9:27 am

> To: Meteorite List <meteorite-list at meteoritecentral.com>

>

>

> topic: grading system for orientation

>

> just trying to get things started off here.

>

> i don't believe there should be 10-grades of orientation, as was

> suggested, as it seems too broad and results in a situation that is

> similar to the one before us: the too-liberal invocation of the

> term. might i suggest a scale of O1-O4 or perhaps to O5 at the most.

>

> it would seem the determination of the extent of orientation should

> be based on the presence of a number of specific characteristics and

> the extent to which such characteristics are manifest. i beseech the

> input of scientists who are expert in eliminating the ambiguities in

> such a grading system.

>

> let's start with some characteristics of orientation that come to

> mind....

>

> evidence of ablation

> presence of flow lines/rivulets

> flow lines radiating in all directions off a single coordinate

> elongated parallel regmaglypts radiating off a single coordinate

> distinctly different morphologies of the obverse and reverse

> evidence of bubbling in the low-pressure zone (reverse)

> parabolic curvature of lead face (including small parabolas at tip of

> oriented "bullets")

> "lipped" edges and evidence of molten material having ablated over

> the edge of such lips

>

>

> please add or subtract to the list. maybe some characteristics

> should be weighted more than others and then there is the quandary of

> quantifying the extent of such characteristics.

>

> i hope this helps to start things off. and i hope we're able to get

> this resolved and get....oriented on orientation.

>

> all best / d,

>

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