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Posted by Derek Lyons on October 7, 2006, 12:41 pm
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>Maybe a Cosmic Snowflake, with a meteoroid nucleus. From the LDEF Teflon
>shield data, it seems that 90% of meteoroid impacts may actually be Cosmic
>Snowflake impacts with the meteoroid as a nucleus.
>Sure looks like what one would expect a big Cosmic Snowflake impact to
>look like.
>http://www.nasa.gov/images/content/160094main_OV104_MMOD_schematic.jpg
>Symmetric blast area inside the honeycomb, one inch in diameter, spanning
>five honeycomb cells. Bottom face sheet cracked, a tension failure of the
>honeycomb cell that was impacted, with a hole from the nucleus showing the
>impact angle.
No - it looks pretty like you'd expect *any* hypervelocity impact to
look like.
D.
--
Touch-twice life. Eat. Drink. Laugh.
-Resolved: To be more temperate in my postings.
Oct 5th, 2004 JDL
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Posted by Craig Fink on October 8, 2006, 7:09 am
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Yeah, you could be right.
Seems honeycomb impacts are different.
http://cat.inist.fr/?aModele=afficheN&cpsidt=15322305
...Previous tests onto aluminium and cadmium facesheets with honeycomb
core (or cylindrical equivalent) and composite facesheets with aluminium
honeycomb core have identified that the honeycomb core influences the
impact process (typically called "channelling")...A honeycomb damage
equation, based on the semi-infinite penetration equation, was compared
with the simulation results. It shows better agreement with both
experimental test results and 2D simulations than the Whipple bumper
shield (Christiansen-Cour-Palais) formulation previously applied to
honeycomb data...
...This is justified since blast loading occurs primarily over an area
equal in diameter to one-half of the sheet spacing...
http://pdf.aiaa.org/jaPreview/JSR/1968/PVJAPRE29514.pdf
Crack =.267 inch, Spacing = .5 inch, but the honeycomb damage is 1 inch in
diameter (2 times the sheet spacing).
Is the honeycomb vented?
You could have supplied some URLs?
Still learning,
--
Craig Fink
Courtesy E-Mail Welcome @ WeBeGood@GMail.Com
--
On Sat, 07 Oct 2006 16:41:35
+0000, Derek Lyons wrote:
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>
> No - it looks pretty like you'd expect *any* hypervelocity impact to
> look like.
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Posted by Jim Oberg on October 5, 2006, 4:18 pm
Please log in for more thread options NASA studying a 'ding' on shuttle
Hole in radiator panel caused by debris impact during Atlantis' flight
http://www.msnbc.msn.com/id/15134114/
By James Oberg, NBC News space analyst // Special to MSNBC //
Updated: October 5, 2006 // 2 pm CDT
Space shuttle experts are examining a small hole that was discovered on
Atlantis after it landed - damage apparently done by a piece of space debris
during the shuttle's flight.
The hole, labeled "Ding 18," is about a tenth of an inch (2.7 mm) in
diameter and goes all the way through a quarter-inch (6 mm) aluminum
honeycomb panel.
It was spotted on the surface of the aft-most segment of the starboard
shuttle thermal radiator, one of two panels that unfold from the
spacecraft's open payload bay doors in flight to dump excess heat from the
cabin. The object missed the nearest pressurized coolant line by several
inches.
Photo -- Two photos, released by NASA on Thursday, show a hole designated
"Ding 18" on a radiator panel on the shuttle Atlantis. The inset photo is a
closeup of the area indicated by orange label in the overall photo of the
radiator panel. "Ding 18" looks like a bullet hole beside the orange label.
http://msnbcmedia.msn.com/j/msnbc/Components/Photos/061005/damage-picture.hmedium.jpg
A cross-section diagram of the damage, released by NASA on Thursday, showed
that behind the tenth-inch entry hole was a blown-out cavity 10 times as
wide. The impact fell fortuitously right between two small pipes (shown in
blue) carrying pressurized coolant through the radiator.
http://msnbcmedia.msn.com/j/msnbc/Components/Photos/061005/damage-diagram.standard.jpg
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Posted by Lee Jay on October 6, 2006, 1:42 pm
Please log in for more thread options Jim Oberg wrote:
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> // NASA studying a 'ding' on shuttle
"Atlantis' six astronauts were never in danger, NASA spokesman Kyle
Herring said Friday."
Uh huh. And if it had hit a window, or someone on EVA?
Someone needs to figure out a way to deal with this threat. I don't
have a solution, but space junk and micrometeorites certainly are
dangerous.
I wish simply saying "shields up" would do the trick.
Lee Jay
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Posted by Radio Buff on October 6, 2006, 8:32 pm
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> Jim Oberg wrote:
>> // NASA studying a 'ding' on shuttle
>
> "Atlantis' six astronauts were never in danger, NASA spokesman Kyle
> Herring said Friday."
>
> Uh huh. And if it had hit a window, or someone on EVA?
>
> Someone needs to figure out a way to deal with this threat. I don't
> have a solution,
...Don't go into space.
But then, everything we do in life has risks of possible death from doing
it. Walking on a sidewalk. Driving a Car. Going to School. Eating Spinach.
Voting for a Democrat.
SC
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>shield data, it seems that 90% of meteoroid impacts may actually be Cosmic
>Snowflake impacts with the meteoroid as a nucleus.
>Sure looks like what one would expect a big Cosmic Snowflake impact to
>look like.
>http://www.nasa.gov/images/content/160094main_OV104_MMOD_schematic.jpg
>Symmetric blast area inside the honeycomb, one inch in diameter, spanning
>five honeycomb cells. Bottom face sheet cracked, a tension failure of the
>honeycomb cell that was impacted, with a hole from the nucleus showing the
>impact angle.