"Scott M. Kozel" wrote:

On Saturday, February 4, 2017 at 2:54:34 PM UTC-5, Jeff Findley wrote:
In article ,
says...
Wrong. The wing leading edge was reinforced carbon-carbon composite.
This was the material on the shuttle which could withstand the most
reentry heating. This isn't something you can "MacGyver" with any spare
parts on board Columbia.

That depends on the exact nature of the damage, and given that it wasn't
surveyed by EVA or by shuttle-based camera or by telescope, we don't know
whether it was a big hole or a small hole, or whether it was on the
leading edge or behind of there. That could not be ascertained after the
fact from the debris on the ground.

True there was no direct evidence. But, based on camera video the size
of the chunk and its velocity when it hit the wing leading edge was
estimated. So, a ground test was performed which was quite shocking in
the size of the hole it created. From Wikipedia:

As demonstrated by ground experiments conducted by the Columbia
Accident Investigation Board, this likely created a 6-to-10-inch
(15 to 25 cm) diameter hole, allowing hot gases to enter the wing
when Columbia later re-entered the atmosphere.

That's a huge hole when you consider the aerodynamic heating at
hypersonic speeds encountered during reentry.


It is still unknown how large the hole was and whether it was
on the leading edge, or rearward where it would have considerably
lower reentry temperatures.


They're pretty damned sure they tracked the departing piece of the RCC
during reentry. If the damage was 'rearward' from the RCC the reentry
would have been successful, so everyone is just pretty damned sure
where the damage was. Read the bloody report.


Also the nature of the damage, was there enough internal structure
to support a patch or was that severely damaged? We don't know
because nobody looked.


And nobody looked because nobody thought the RCC could be damage by a
foam strike and tile damage wouldn't have led to loss of vehicle.


If they did an EVA or had a Canadarm with a remote camera, they
could have made a very accurate assessment of whether it was
repairable, and on day 2.


If they even looked in the right place. Again, nobody believed at the
time that the RCC could be damaged by a foam strike. Kits to repair
damaged tiles didn't exist until years after Columbia, so even finding
tile damage would have made no difference since there was no way to
repair that at the time, either.

snip


That is why I suggested sending an expendable rocket with materials to
for Columbia crew to make an emergency patch. Titanium sheets and
sheets of ablative material and fasteners, for example.

But that quite simply would not work for the RCC wing leading edge. The
best NASA could do was make a repair kit for the tiles.

Again, they didn't know whether it was the leading edge or the exact
nature of the damage. The expendable rocket could send up several tons of various materials, using whatever was deemed necessary.


Again, they were pretty sure it was NOT the leading edge until after
the fact, since no one believed that a foam strike could damage the
RCC. They'd done lots of work on what it took to damage the RCC
because of concerns about on orbit damage (which they'd seen on
various missions), but all that work assumed relatively small
impactors at relatively high velocities. Nobody had looked at impacts
from large chunks of foam at several hundred miles an hour and when
they did look they quickly discovered that such an impact would blow
huge holes in the RCC.

snip


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