Want to learn more about our mission-flown Space Shuttle Columbia HRSI tile? This specimen was removed on May 15, 1986 between Columbia's 7th and 8th flight. We knew this swap was made due to excessive damage to the tile and that there was another issue with the tile not being "densified." However, other details from the discrepancy report issued with the tile's decommission were more difficult to discern.
That is, until recently! We were lucky enough to have a chat with the former Lead Engineer of Atlantis's Thermal Protection System (TPS), Charlie Romeo. Charlie was kind enough to give us an extremely detailed breakdown of the Columbia tile report! Not only that, but he also included many stories from his time as a contributor to the Space Shuttle Program and what life was like at the Kennedy Space Center during that era of space exploration. We're excited to share these incredible new details about our shuttle material!
📸 Columbia after arrival to the Orbiter Processing Facility in 1979
Between missions, the shuttles were maintained in the Orbiter Processing Facility or OPF. They were massive hangars: each over 250 feet long, 150 feet wide, and 95 feet in height. Technicians could walk on movable platforms to access the upper parts of the shuttle while jacks brought the bottom of the shuttle about eight feet off the floor for work on the underside.
Since this was the only time the shuttle was in a horizontal position on the ground (the shuttles were vertical in the Vehicle Assembly Building and on the launchpad), this is where our tile was inspected and removed. Our document notes that Columbia was in OPF Bay 1 at the time of maintenance.
📸 A classic cutaway drawing of the Space Shuttle created by NASA artists in February, 1981
While in the hangar, Romeo noted certain constraints could be filed, essentially steps required to be completed before the shuttle could be moved again. This was an extremely important process:
"You did not want to be the engineer that missed a constraint, and the vehicle rolled to the pad with an open tile cavity. Applying correct constraints was one of my pet peeves. I trained many engineers on the proper use of constraints, yet some failed to see the importance. That is until they missed one and got called to the 6th floor, where they had to deal with the Chief Engineer and the Director of Orbiter Processing. You really did not want to be invited to that room."
📸 A Diagram of Space Shuttle Tiles and locations. You can find where our tile sat around the aft (395903-145)
Much of the excitement in our discrepancy report lies in Block 17, the Problem Description. Here, the type of tile is selected (black HRSI for this one!) The report notes that this was one of several tiles around the fuselage that showed "excessive damage." At the moment of liftoff, these tiles were subjected to intense heat and "peppering." There is something more here though: the "not densified" problem.
During processing for the STS-1 launch, TPS technicians discovered the tiles used for the shuttle simply would not be strong enough to survive the tensile loads of a flight:
"This test applied approximately 250 lbs tensile load to the tile after it was bonded to provide a general indication that the installation was good and that the RTV adhesive cured properly. What was happening was tiles were breaking just above the bondline at approximately 4 to 6 psi. NOT GOOD."
The solution put in place by engineers was "densification," a process where the tiles were covered with a special slurry mixture consisting of a water-based liquid, silica, and a chemical called Ludox. The tiles had to be taken off and handworked with the silica solution, dried, and baked in order to form the strengthened layer. Romeo explained how crucial this process was the the initial launch:
"It basically saved the program. So, all tiles on the lower surface of the vehicle, approximately 15,000 give or take, had to be removed, densified, and reinstalled prior to STS-1. This issue significantly affected the launch date of STS-1. At one point there were over 600 TPS technicians removing and replacing tiles. My wife was one of them."
Mini Museum's tile was one of very few that missed this process and ended up flying seven missions before being removed. Columbia was the only shuttle to be constructed before the densification process was required for tile manufacturing, so this tile is one of the only un-densified Space Shuttle tiles ever flown.
📸 A macro image showing the profile of the specimen and the black, reaction-cured glass coating. The tip of a ballpoint pen appears for scale.
But wait, the story of this tile's history with densification doesn’t end there! When working on embedding this tile into acrylic for our MM4 collections, we ran into a problem of our own: the specimen couldn't hold up to the embedment process and would fall apart.
The solution? Checking with this very discrepancy report we figured we may find success densifying the tile on our own! This idea came to us from our work with fossil material, which often needs to be densified to save a crumbly piece for display or study. Applying this knowledge to the shuttle material and armed with a bottle of Cactus Juice resin, the Columbia tile in our collection was densified and we found it worked perfectly! The tile remained stable in our next acrylic tests!
📸 The first launch of Space Shuttle Columbia
We are indebted to Charlie Romeo's fantastic insight and in awe of the many stories and exciting moments from his career that he's shared. Those details go over the entirety of the discrepancy report, which you can see in full below. There's a lot to learn there (including the hilarious story behind the Bay 1 Aft TPS Shop's telephone number!) Thank you again Charlie for letting us share this knowledge!
If you want to learn more about the Space Shuttle Program, check out our collection of material here!
Explore the full discrepancy report, and read all of Charlie Romeo's notes in full here!
Space Shuttle Columbia - Flown HRSI Tile Fragment
Space Shuttle Columbia - Flown HRSI Tile Fragment
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