Re: [rp-ml] Earlier posting that didn't get through

From: Yasser Hosni (
Date: Sat Aug 25 2007 - 00:28:27 EEST

George and all:
I have had some experience with the damaged thermal tiles on the space shuttle in the old days. You may remember that the tile separation and/or damage was not an anticipated problem in the original design. Early space missions used to have quite a number of damaged tiles. As you know the tiles are geometrically unique and they are"glued" to the orbiter. The tile maintenance procedure at that time include two interesting engineering challenges:
(1) Capturing the 3D geometry of the cavity (left over from lost/ damaged tiles), to enable manufacturing a replacement tile.
(2) Testing the tile after it is glued to the orbiter without damaging it.

At the time, reverse engineering was suggested as a means of capturing the 3D geometry- Challenge (1) above (it was not allowed to touch (have contact) to the orbiter). The state of technology at the time was not up to the challenge. Since then, there are an impressive, accurate equipment that would enable 3D capturing. I imagine that what is used in the "3D faxing" is the outcome of these equipment coupled with sophisticated communication systems!
While I am not sure what type of stereolithography is being talked about it may have to do with the "slicing" idea in the quest for replicating the damage in 3D virtually or physically.
It is interesting to see how technology is advancing and being integrated to solve challenging problems.
I am not sure how Challenge (2) is being resolved. At the time of my involvement, the area(s) of coverage of adhesive material, was being used to comparatively assess the glueing process!
Of course a better approach is to devise a way to eliminate the separation/ damage of the tile in the first place, but that may be an expensive venture that may require redesign!

take care.


Yasser Hosni, Ph.D., PE.
Industrial Engineering and Management Systems
University of Central Florida
4000 Central Florida Blvd.
Orlando, FL 32816
Tel (407) 823-5817
Fax (407) 823-3413

>>> George Sachs <> 08/24/07 2:47 PM >>>
I don't know how many on the list were aware of the details behind the recent Shuttle tile problems, so some of you might be interested in this, if you haven't already heard about it.

Sent: Monday, August 13, 2007 2:10:46 PM
Subject: [rp-ml] Important application of RP & RM - happening right now
I was listening to the live feed from NASA yesterday and learned that they will be using the point cloud data that they got from scanning the
damage to the Shuttle's tiles to exactly re-create the damage back on earth.
They will also use 3D printing to help in this process (they said stereolithography, but it could also be some other methods.). I guess this is as good
an example of "3D faxing" as they come. The replicated tile damage (probably made by machining real tiles or maybe casting) will be analyzed with software and
the duplicated damaged tiles will also be put into a plasma jet stream to see how dangerous the situation is and what fixes (if any) might or might
not work. They hope to make results of these tests along with their decision about what to do made available later today or tomorrow. It sounds
like they are doing a tremendous job "working the problem" and I have lots of confidence they will find the right solution with some help from RP.

G. Sachs
Paradyme Systems

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