Tile and RCC repair for return to flight

I think someone mentioned something about whether RCC repair was the
long pole in the tent for shuttle return to flight. Well, I thought
I'd check on this. The short summary seems to be that tile repair
should be ready, and RCC repair indeed is much more of an unknown at
this point.

My source is http://www.nasa.gov/news/highlights/returntoflight.html
specifically the big PDF (Implementation Plan for Space Shuttle Return
to Flight and Beyond, revision 2.2, 30 Aug 2004) which says:

RCC Repair

The main challenges to repairing RCC are maintaining
a bond to the RCC coating during entry heating and
meeting very small edge step requirements. The RCC
repair project is pursuing two complementary repair
concepts that together will enable repair of a range
of RCC damage: Plug Repair and Crack Repair. Plug
Repair consists of an insert intended to repair holes in the
WLE with sizes from 0.5 in. to 4 in. in diameter. Crack
Repair uses a material application intended to fill cracks
and small holes in the WLE. Both concepts are expected
to have limitations in terms of damage characteristics,
damage location, and testing/analysis. Schedules for
design, development, testing, evaluation, and production
of these concepts are in work. A third repair concept,
RCC rigid overwrap, encountered problems during devel-
opment and was shown to be infeasible to implement in
the near term; as a result, it was deleted from considera-
tion for RTF. NASA is continuing research and develop-
ment on a long-term, more flexible RCC repair technique
for holes over 4 in. in diameter.

This effort is still in the concept definition phase and is
much less mature than the tile repair material study. NASA
is evaluating concepts across six NASA centers, 11 contrac-
tors, and the United States Air Force Research Laboratory.

Although we are aggressively pursuing RCC repair, it is too
early in development to forecast a completion date.

Tile Repair

NASA has made significant progress in developing credible
tile repair processes and materials. A formulation derived
from an existing, silicone-based, cure-in-place ablator showed
good thermal performance results in development testing in
2003. Tests confirmed that the repair material adheres to
aluminum, primed aluminum, tile, strain isolation pads,
and tile adhesive in vacuum and cures in vacuum. After
these successful tests, NASA transitioned to characteriza-
tion and qualification testing. Detailed thermal analyses
and testing are under way to confirm that the material can
be applied and cured in the full range of orbit conditions.

It goes on with more about the tile repair (and of course the PDF, all
284 pages of it, is full of similar details about all aspects of
return to flight).

Jim Kingdon wrote


[Various excisions performed]

My source is http://www.nasa.gov/news/highlights/returntoflight.html
specifically the big PDF (Implementation Plan for Space Shuttle Return
to Flight and Beyond, revision 2.2, 30 Aug 2004) which says:

RCC Repair

NASA is continuing research and develop-
ment on a long-term, more flexible RCC repair technique
for holes over 4 in. in diameter.


IOW, they're still looking for a way to repair the
size of hole thought to be responsible for the destruction
of Columbia?


http://www.memagazine.org/backissues.../thetrail.html


Investigators launched a piece of foam at the RCC
panel 8 at 530 mph at an angle of about 20 degrees.
The impact blew a large hole in the panel, some 16 inches
square. Thermal analysis performed by the NASA investigation
team indicated that a hole 10 inches across would have been
enough to bring the orbiter down and would have corresponded
consistently with the sensor data of Columbia's last flight.

"Allen Thomson"

IOW, they're still looking for a way to repair the
size of hole thought to be responsible for the destruction
of Columbia?

No, they are not still looking. The repair of a hole similar to the one
on Columbia was never feasible. This has been in the press and related
by NASA people numerous times from the beginning of the return to flight
efforts. Did you miss these reports, or is your question rhetorical?