Shuttle damage pierces tile.

ABC news just had a breaking story that states that the tile damage on
the Shuttle goes clean through the silica layer of the tile and that
the felt attachment layer is exposed.

Pat

Pat Flannery wrote:
ABC news just had a breaking story that states that the tile damage on
the Shuttle goes clean through the silica layer of the tile and that
the felt attachment layer is exposed.
http://www.abcnews.go.com/Technology...ory?id=3471980

Pat

On Aug 12, 3:48 pm, Pat Flannery wrote:
Pat Flannery wrote:
ABC news just had a breaking story that states that the tile damage on
the Shuttle goes clean through the silica layer of the tile and that
the felt attachment layer is exposed.

http://www.abcnews.go.com/Technology...ory?id=3471980

Pat

Thought it was notable that during the launch , the on-board video
broadcast did not show SRB seperation, (although we got ET sep) think
NASA found it to boring to broadcast? All viewers got was a long
range ground view of the SRB sep.. Does this video exist or were the
cameras not broadcasting?................Doc

wrote:

Thought it was notable that during the launch , the on-board video
broadcast did not show SRB seperation, (although we got ET sep) think
NASA found it to boring to broadcast? All viewers got was a long
range ground view of the SRB sep.. Does this video exist or were the
cameras not broadcasting?................Doc


I thought that it was broadcast but they weren't showing it (at least on
CNN), because they were showing the ground view of the separation
instead, due to the clear skies permitting them to photograph the
Shuttle well from the ground during ascent.
It should exist though as the rest of the ET camera ascent video was of
excellent quality.
What threw me was the early NASA statement that the debris events were
possibly ice shedding from the ET, because the temperature at launch was
near 100 F., and if ice can form on the ET foam in heat like that you
have a problem.
From what I've hearing and reading today, the foam seems to be related
to the PAL ramp again, and bounced off the bipod ramp and struck the
Shuttle belly at a pretty good velocity.
They are saying the foam chunk was about the size of a grapefruit, which
is pretty substantial.
The reports keep making reference to the impact being seen by radar
imagery, but the ABC News report on television did show video footage of
it occurring from the ET camera. There is some reference to debris being
seen behind the Shuttle after the impact due to the foam breaking up, so
maybe that's what the radar showed.

Pat

Pat Flannery wrote:


Pat Flannery wrote:
ABC news just had a breaking story that states that the tile damage on
the Shuttle goes clean through the silica layer of the tile and that
the felt attachment layer is exposed.
http://www.abcnews.go.com/Technology...ory?id=3471980

Pat

"In a stroke of luck, they're right beneath the aluminum framework for
the right wing, which would offer extra protection during the ride back
to Earth."

Given that the aluminium (yanks don't know how to spell) would melt, I
find this an odd usage of the word "luck".

Sylvia.

Sylvia Else wrote:

"In a stroke of luck, they're right beneath the aluminum framework for
the right wing, which would offer extra protection during the ride
back to Earth."

Given that the aluminium (yanks don't know how to spell) would melt, I
find this an odd usage of the word "luck".

I think the concept is that the reentry plasma would have to get through
the skin and framework it's attached to before getting inside the wing's
internal structure. IIRC, there has been a case before where a burning
of the aluminum skin has occurred due to tile damage, and although it
was expensive to repair, it didn't do major damage to the Shuttle.
The big problem with tile damage is the dread hypothesized "zipper
effect"- one tile disintegrates during reentry, and this starts causing
tiles aft of it to fail and fall off also as the skin overheats in the
superheated turbulent airflow caused by the missing tile...until you
have a big hole in the wing and its structure fails.
The damage is somewhat worrying because it's at the junction point of
three tiles. in the center of one, and the tile hadn't cracked in half,
they might be less concerned.
Anyway, if they decide to do a repair, this is the type damage to do a
repair on; the hole is quite small, and it's on area of the underbelly
that doesn't have a complex aerodynamic shape, so the repair can be
basically flat in form.

Pat

On Aug 12, 9:19 pm, Pat Flannery wrote:
Sylvia Else wrote:

"In a stroke of luck, they're right beneath the aluminum framework for
the right wing, which would offer extra protection during the ride
back to Earth."

Given that the aluminium (yanks don't know how to spell) would melt, I
find this an odd usage of the word "luck".

I think the concept is that the reentry plasma would have to get through
the skin and framework it's attached to before getting inside the wing's
internal structure. IIRC, there has been a case before where a burning
of the aluminum skin has occurred due to tile damage, and although it
was expensive to repair, it didn't do major damage to the Shuttle.

Naah. The damaged tile will cause intense heating in a localized
area, which will get conducted into the rest of the structure. If it
was a patch of skin, the heat could not be conducted away very
quickly, so the skin would get hot enough to melt. The stringer will
conduct the heat away quickly enough that the structural temperatures
won't get high enough to cause a problem, or at least that seems to be
the theory.

Which just goes to show that the theory about the best way to get an
answer on USENET is not to ask a question but to make an incorrect
assertion is still valid...

-jake

Jake McGuire wrote:
On Aug 12, 9:19 pm, Pat Flannery wrote:
Sylvia Else wrote:

"In a stroke of luck, they're right beneath the aluminum framework for
the right wing, which would offer extra protection during the ride
back to Earth."
Given that the aluminium (yanks don't know how to spell) would melt, I
find this an odd usage of the word "luck".
I think the concept is that the reentry plasma would have to get through
the skin and framework it's attached to before getting inside the wing's
internal structure. IIRC, there has been a case before where a burning
of the aluminum skin has occurred due to tile damage, and although it
was expensive to repair, it didn't do major damage to the Shuttle.

Naah. The damaged tile will cause intense heating in a localized
area, which will get conducted into the rest of the structure. If it
was a patch of skin, the heat could not be conducted away very
quickly, so the skin would get hot enough to melt. The stringer will
conduct the heat away quickly enough that the structural temperatures
won't get high enough to cause a problem, or at least that seems to be
the theory.

Which just goes to show that the theory about the best way to get an
answer on USENET is not to ask a question but to make an incorrect
assertion is still valid...

-jake


As somewhat of an aside, I came across this document about the thermal
protection system

http://ntrs.nasa.gov/archive/nasa/ca...1993023009.pdf

On page 9 it tabulates the number of distinct damage locations sustained
by the thermal protection system on each mission. On some missions it
approaches 300.

Sylvia.

Jake McGuire wrote:

On Aug 12, 9:19 pm, Pat Flannery wrote:
Sylvia Else wrote:

"In a stroke of luck, they're right beneath the aluminum framework for
the right wing, which would offer extra protection during the ride
back to Earth."

Given that the aluminium (yanks don't know how to spell) would melt, I
find this an odd usage of the word "luck".

I think the concept is that the reentry plasma would have to get through
the skin and framework it's attached to before getting inside the wing's
internal structure. IIRC, there has been a case before where a burning
of the aluminum skin has occurred due to tile damage, and although it
was expensive to repair, it didn't do major damage to the Shuttle.

Naah. The damaged tile will cause intense heating in a localized
area, which will get conducted into the rest of the structure. If it
was a patch of skin, the heat could not be conducted away very
quickly, so the skin would get hot enough to melt. The stringer will
conduct the heat away quickly enough that the structural temperatures
won't get high enough to cause a problem, or at least that seems to be
the theory.

Theory, but doing a high gee turn, like the one around the Heading Alignment
Cone with a softened aluminum structure may not be the best thing to do.

Jake McGuire wrote:
Naah. The damaged tile will cause intense heating in a localized
area, which will get conducted into the rest of the structure. If it
was a patch of skin, the heat could not be conducted away very
quickly, so the skin would get hot enough to melt.

It will get through the felt fairly quickly. Then the skin itself in a
small area will be exposed to the plasma.
I don't think it will transfer the heat away fast enough to prevent
damage to the aluminum, particularly given the fact that hat the plasma
is going to consist of is largely atomic oxygen, which is highly corrosive.
An analogy would be holding a oxyacetylene torch up to a sheet of
aluminum and expecting the metal to transfer the heat away fast enough
for it not to get a hole melted in it.
You may end up with a small, very hot hole in the structure, and some
vaporised aluminum getting sprayed around inside the wing.There's a
problem with the wing framework member it's attached to heating up
also... that's going to cause it to expand which could lead to problems
with how it's stressed against the skin.
I'm not going to be surprised at all if they decide to patch the ding
before reentry, if for no other reason than doing that is going to save
costly repairs to the wing skinning that might be needed if they let it
stay as is, even if it's not a real danger to a safe reentry.
I would think this gives them the perfect chance to try out a repair
where they can see how well it worked after landing.
If they can't even fix something this small on a flat area of the belly
TPS, they might just as well give up doing repairs on-orbit, as this is
about the most minor damage to the belly that they'd be likely to think
needed repairs.

Pat