Mysterious Object

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Al Jackson

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Mar 6, 2003, 7:14:59 PM3/6/03
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Mysterious Object

This is the best analysis I have seen of the object seen coming from
the vicinity of the Columbia.

http://www.satobs.org/columbia/STS107mysteryobject.html

This brings up the thought. Did the ET debris hit during ascent only
loosen a tile, which then took a orbit debris strike in orbit and was
thus dislodged? The strike might only be from a 1mm space debris
object.

Boris Nogoodnik

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Mar 6, 2003, 8:59:05 PM3/6/03
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"Al Jackson" <aa...@flash.net> wrote in message
news:fa9de496.03030...@posting.google.com...

Interesting. But good question is if the object of this size
made out of dielectric material whould show on the radar at all?


Brian Gaff

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Mar 7, 2003, 4:54:37 AM3/7/03
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ia...@blueyonder.co.uk
"Boris Nogoodnik" <n...@spam.org> wrote in message
news:J1T9a.33085$gf7.6...@news4.srv.hcvlny.cv.net...
Yes, I was wondering the same, I seem to recall when I was workning with
Radars, albeit clunky Marine and such, that it really did matter what pulse
width and frequency you used as to how different materials were seen.

What sort of radar is used routinely for this tracking of orbiting
'things'?
My feelings about the damage to the tiles revolve around the sheered of but
not completely removed ideas. This might be the result of a severe shock,
say from foam, and would be extremely hard to see, if the tiles were still
held in place by the material between them.

However, remove just one from the pile, as it were, and others could just
float away.

The resulting rough surface of half, domed and broken tiles would indeed
cause terrible drag, and might, through the messy airflow have allowed a
burn through that started the process of destruction.

Brian

--
Brian Gaff - Sorry, can't see pictures, graphics are great, but the blind
can't hear them
br

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Boris Nogoodnik

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Mar 7, 2003, 5:57:48 AM3/7/03
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"Brian Gaff" <Bri...@blueyonder.co.uk> wrote in message
news:b49qg1$1rpree$2...@ID-105134.news.dfncis.de...

Still one thing that make this whole thing irrelevent is the
fact than not electically conductive material would make all the
calculations stated in this article completely wrong. Radar
observation only gives you "radar" cross section return. It
does not tell you anything about the composition of the
material. But to get a return, it must be condictive. Carbon
fiber or selicone based tiles won't give you any return. So it
must be some metal thing. Then all the calculations are way
off.

Brian Gaff

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Mar 7, 2003, 6:33:29 AM3/7/03
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"Boris Nogoodnik" <n...@spam.org> wrote in message
news:MW_9a.44331$gf7.7...@news4.srv.hcvlny.cv.net...

|
| "Brian Gaff" <Bri...@blueyonder.co.uk> wrote in message
| news:b49qg1$1rpree$2...@ID-105134.news.dfncis.de...
| > ia...@blueyonder.co.uk
| > "Boris Nogoodnik" <n...@spam.org> wrote in message
| > news:J1T9a.33085$gf7.6...@news4.srv.hcvlny.cv.net...
| > | "Al Jackson" <aa...@flash.net> wrote in message
| > | news:fa9de496.03030...@posting.google.com...
| > | > Mysterious Object
| > | >
| > | > This is the best analysis I have seen of the object seen
| > | coming from
| > | > the vicinity of the Columbia.
| > | >
| > | > http://www.satobs.org/columbia/STS107mysteryobject.html
| > | >
| > | > This brings up the thought. Did the ET debris hit during
| > | ascent only
| > | > loosen a tile, which then took a orbit debris strike in
| orbit
| > | and was
| > | > thus dislodged? The strike might only be from a 1mm space
| > | debris
| > | > object.
| > |
| > | Interesting. But good question is if the object of this
| size
| > | made out of dielectric material would show on the radar at

| all?
| > |
| > |
| > Yes, I was wondering the same, I seem to recall when I was
| working with
| Still one thing that make this whole thing irrelevant is the
| fact than not electrically conductive material would make all the

| calculations stated in this article completely wrong. Radar
| observation only gives you "radar" cross section return. It
| does not tell you anything about the composition of the
| material. But to get a return, it must be conductive. Carbon

| fiber or selicone based tiles won't give you any return. So it
| must be some metal thing. Then all the calculations are way
| off.
|
|
|

Ok, I'd agree from what I know, but as we will never know for sure what it
was, and taking your point about reflectivity, we need to say...

1 Its a red herring that was just 'there' by coincidence, or...
It came away from the cargo bay, begging the question of how well was any
inspection done before launch?
or, the damage was bad enough to cause some metallic item to detach
somewhere.

I'd have thought that if it had been leading edge, with associated stainless
mounting hardware, that wood have been visible from the cabin.

So, when the tank separates, what does it leave on the shuttle end? Just
wondering if some piece of hardware clung on for a while till the shuttle
Manouvered.

Brian

--
Brian Gaff - Sorry, can't see pictures, graphics are great, but the blind
can't hear them

bri...@blueyonder.co.uk

ed kyle

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Mar 7, 2003, 12:09:27 PM3/7/03
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aa...@flash.net (Al Jackson) wrote in message news:<fa9de496.03030...@posting.google.com>...

The odds of this happening - of an orbital debris strike hitting
the *exact* same spot where ET debris struck during the same
mission - are too small to make this a plausible theory. It
is much more likely that a damaged component worked its way
loose due to on-orbit thermal cycling and/or forces from
thruster firings.

- Ed Kyle

Hobbs

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Mar 7, 2003, 12:21:47 PM3/7/03
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"Boris Nogoodnik" <n...@spam.org> wrote in message news:<MW_9a.44331

> Still one thing that make this whole thing irrelevent is the
> fact than not electically conductive material would make all the
> calculations stated in this article completely wrong. Radar
> observation only gives you "radar" cross section return. It
> does not tell you anything about the composition of the
> material. But to get a return, it must be condictive. Carbon
> fiber or selicone based tiles won't give you any return. So it
> must be some metal thing. Then all the calculations are way
> off.

Are you saying that carbon covered rentry vehicles like nuclear
warheads cannot be tracked by DOD radars? Even the most advanced
stealth aircraft can be tracked by radar but it's true that
without knowing what the thing is made up determining the size
can be difficult.

-McDaniel

David Harper

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Mar 7, 2003, 12:22:37 PM3/7/03
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"Boris Nogoodnik" <n...@spam.org> wrote in message news:<MW_9a.44331>
> Still one thing that make this whole thing irrelevent is the
> fact than not electically conductive material would make all the
> calculations stated in this article completely wrong. Radar
> observation only gives you "radar" cross section return. It
> does not tell you anything about the composition of the
> material. But to get a return, it must be condictive.
(snip)

I'm skeptical of that statement. Radar mapping missions wouldn't be
able to image ground terrain if only conductive materials provided a
return. Why do you state only conductive materials allow a return?

Brian Gaff

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Mar 7, 2003, 12:50:55 PM3/7/03
to

By the way, my comment about the pulse width and frequency of the radar was
meant to mean that materials that are non cunductive can be imaged to some
extent by varying these parameters. You would need Somme active attenuation
in a material to stop reflections altogether. The different densities oor a
boundary between materials can give some reflection.

Brian

--
Brian Gaff - Sorry, can't see pictures, graphics are great, but the blind
can't hear them

bri...@blueyonder.co.uk

Allen Thomson

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Mar 7, 2003, 1:35:56 PM3/7/03
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"Boris Nogoodnik" <n...@spam.org> wrote

> Still one thing that make this whole thing irrelevent is the
> fact than not electically conductive material would make all the
> calculations stated in this article completely wrong. Radar
> observation only gives you "radar" cross section return.

Well, not all the calculations, as the radar data entered only
via the physical dimensions that NASA gave. Those dimensions
were deduced by USSTRATCOM on the basis of multiple radar
observations carried out by its space surveillance network.

It can't be excluded that STRATCOM's figures are in error;
OTOH they do this kind of thing for a living and I'd be inclined
to take their dimensions as a reasonable starting point.

> It
> does not tell you anything about the composition of the
> material.

If returns from radars operating at different frequencies are
available, some rough indications of composition might be backed
out. One trusts such analyses are underway even as we speak.

> But to get a return, it must be condictive. Carbon
> fiber or selicone based tiles won't give you any return. So it
> must be some metal thing. Then all the calculations are way
> off.

Sigh. There is an unfortunately widespread belief that radar only
reflects off metallic objects. That's no more true for radar than
it is for visible light, and for the same reason. Let's see....

Here we go. The dielectric constants of vacuum and air are
quite similar, so the following text applies to the present case.


http://www.btinternet.com/~jmcgroves/radarsignaturereduction.htm

[Radar] Reflectivity

Reflection from conductors

[snip]

Reflection from non-conductors

With a non-conductive target surface hit by a radar beam in air, the
ratio of the dielectric constant of the material of the surface to
that of air controls the proportion of radiation power that is
reflected back to the source. This is because the dielectric constant
of the medium through which the beam is travelling describes the
division of the beam's total energy between the electric and magnetic
propagating fields. When the beam enters a material with a different
dielectric constant, some of the beam's energy must be reflected to
maintain the balance. Similarly, entry into a magnetic material also
causes a proportion of the beam to reflect.

Boris Nogoodnik

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Mar 7, 2003, 11:10:20 PM3/7/03
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"Hobbs" <mcdani...@yahoo.com> wrote in message
news:a1405269.03030...@posting.google.com...

Stealth technology uses several methods to conceal metal parts
inside to some degree. It's mainly deflection and absorption.
However pure non conductive material shouldn't produce any
returns if there are no metal parts inside. So I assume this
object was mainly metal.


Boris Nogoodnik

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Mar 8, 2003, 12:46:42 AM3/8/03
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"David Harper" <achil...@hotmail.com> wrote in message
news:fef44ceb.03030...@posting.google.com...

It was a simple case of the small object in space. Sure some
radar energy is reflected back when it enters the matter with
different dielectric properties. But figuring the size, mass
and composition is hardly possible.


Al Jackson

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Mar 9, 2003, 2:12:57 PM3/9/03
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edky...@hotmail.com (ed kyle) wrote in message news:<88d21cfd.03030...@posting.google.com>...

Quite true, I should have noted that.

By the by, Allen Thomson , exposition on radar reflection from non-metallic
objects is excellent!

Duncan

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Mar 10, 2003, 12:04:52 PM3/10/03
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If you don't think carbon fiber is conductive, try throwing a carbon
fiber clad board over the terminals of a battery. I was working with a
thin sheep of balsa wood with carbon fiber sheets on both sides and I
casually tossed it onto a table that I had a camcorder battery on. I
walked away and within about three minutes the board was on fire! This
led me to believe that carbon fiber was INDEED conductive.

bye
Duncan

Hobbs

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Mar 10, 2003, 7:58:31 PM3/10/03
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"Boris Nogoodnik" <n...@spam.org> wrote in message news:<M2eaa.56454$gf7.10...@news4.srv.hcvlny.cv.net>...

You're assuming that the shuttle only normally emits pure water?? And
that pure water cannot be detected by radar?? I think both
assumptions are wrong.

-McDaniel

Hobbs

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Mar 10, 2003, 8:00:45 PM3/10/03
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Duncan <dun...@winnd.sparks.nv.us> wrote in message news:<3e6cc6a6

I think anything materuak is conductive if you put enough electricity
at it.

-McDaniel

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