Tiles a product of valley / STS-107

SJ Mercury News ^ | 2/4/03 | Aaron Davis and Joshua L. Kwan

[NormsRevenge]

A small sample of a space shuttle tile glows during a demonstration by Kennedy Space Center's Visitor Center educationalist Jeff Lucas.

The protective ceramic tiles on the space shuttle -- invented, designed, tested and produced in Silicon Valley -- are at the center of the investigation into what caused the Columbia disaster.

[prognostigaator]

A 'new' environmentally safe foam was currently used on this launch and the recent other launches . It had replaced the original 'freon' based foam on the lox tanks to make it 'environmentally safe' . Frozen solid when striking the shuttle's wing, it would not be the soft spongy stuff one would associate with cushioning in furniture ......[my two cents..jh2]

[Grammy]

Not all research was done in Silicone Valley. Mr Grammy's father also did much research on them (he was a ceramic engineer). The tiles are more like styrofoam than ceramic, and they are indeed very fragile. Mr Grammy says they are very easily scratched.

[oust the louse]

Hey Mr Grammy,just as an aside,I am a recruiter in the Ceramics industry.I have talked with many engineers who were intimately involved in the space program and who supplied into the program....

[NormsRevenge]

Nice to make your acquaintance and thanks for your Dad's work as well. Did he know any of the folks in the Lockheed end of things? I think Rockwell also did some work in this area too.

[honway]

How are the tiles attached to the shuttle?

[honway]

http://www.twi.co.uk/j32k/protected/band_3/ksat001.html

The NASA Space Shuttle employs 24 000 ceramic tiles as a thermal protection system to keep the temperature inside the vehicle relatively constant. The external temperature of the tiles can vary between -80°C during orbit to 1250°C during re-entry. These tiles are adhesively bonded via a strain isolation pad to the aluminium skin of the shuttle, and the skin has a design limit of 175°C. The success of this system not only allows the shuttles to operate but permits them to be re-used many times

[honway]

The densification process was developed from a Ludox ammonia-stabilized binder. When mixed with silica slip particles, it becomes a cement. When mixed with water, it dries to a finished hard surface. A silica-tetraboride coloring agent is mixed with the compound for penetration identification. Several coats of the pigmented Ludox slip slurry are brush-painted on the SIP/tile bond interface and allowed to air-dry for 24 hours. A heat treatment and other processing are done before installation. The densification coating penetrates the tile to a depth of 0.125 inch, and the strength and stiffness of the tile and SIP system are increased by a factor of two.

[honway]

To prevent damage to the tiles, Strain Isolation Pads - a layer of nylon felt Nomex (flame-retardant material)- are used between the tiles and the orbiter's surface. The pads are bonded to the tiles, as well as to the skin of the Shuttle, with RTV, a room-temperature vulcanizing silicone adhesive. The tile surface bonded to the pads is densified with silica-type solutions for added tensile strength

[hunter112]

I was wondering about this so-called "foam", I couldn't imagine how foam could damage something meant to survive the heat of coming into Earth's atmosphere. Now I see what its about.

The reason Florida was chosen for the launch sites for America's space program was the weather. Seems to me that they need to ban flights in December or January, since the ninnies at NASA don't seem to get it. It was cold O-rings that led to the Challenger disaster, wasn't it? Keeping a time schedule regardless of the weather is of no service to our astronauts.

[honway]

http://esapub.esrin.esa.it/bulletin/bullet80/keller80.htm

The flexible blankets (FRSI) were originally made from a Nomex felt. A white silicone elastomer coating provided the required thermo-optical properties and the water-proofing. The blankets were bonded directly to the aluminium airframe with a silicone-based adhesive.

More than 60 successful Orbiter flights and the Buran flight have validated this thermal-protection concept. The RSI has evolved during its use on the Shuttle. Firstly, rigid ceramic tiles with greater mechanical strength and higher application temperatures were developed, by adding alumino-boro-silicate fibres to the silica fibres before the sintering step. Secondly, advanced flexible blankets (AFRSI) have been realised by replacing the Nomex felt by a silica felt. The thermal endurance was significantly enhanced in this way, from ³70 to some 650° C. The AFRSI blankets replaced the original rigid tiles for large leeward surface areas of the Orbiter, resulting both in reduced fabrication/ installation time and costs, and lower TPS weight.

[honway]

http://spaceflight.nasa.gov/shuttle/reference/shutref/orbiter/tps/blankets.html

Advanced Flexible Reusable Surface Insulation Blankets

AFRSI blankets replace the vast majority of the LRSI tiles. AFRSI consists of a low-density fibrous silica batting that is made up of high-purity silica and 99.8-percent amorphous silica fibers (1 to 2 mils thick). This batting is sandwiched between an outer woven silica high-temperature fabric and an inner woven glass lower temperature fabric. After the composite is sewn with silica thread, it has a quiltlike appearance. The AFRSI blankets are coated with a ceramic collodial silica and high-purity silica fibers (referred to as C-9) that provide endurance. The AFRSI composite density is approximately 8 to 9 pounds per cubic foot and varies in thickness from 0.45 to 0.95 inch. The thickness is determined by the heat load the blanket encounters during entry. The blankets are cut to the planform shape required and bonded directly to the orbiter by RTV silicon adhesive 0.20 inch thick. The very thin glue line reduces weight and minimizes the thermal expansion during temperature changes. The sewn quilted fabric blanket is manufactured by Rockwell in 3- by 3-foot squares of the proper thickness. The direct application of the blankets to the orbiter results in weight reduction, improved producibility and durability, reduced fabrication and installation cost, and reduced installation schedule time.

[honway]

http://spaceflight.nasa.gov/shuttle/reference/shutref/mods/orbiter/tps.html


Thermal Protection System
The area aft of the reinforced carbon-carbon nose cap to the nose landing gear doors has sustained damage (tile slumping) during flight operations from impact during ascent and overheating during re-entry. This area, which previously was covered with high-temperature reusable surface insulation tiles, will now be covered with reinforced carbon-carbon.

The low-temperature thermal protection system tiles on Columbia's midbody, payload bay doors and vertical tail were replaced with advanced flexible reusable surface insulation blankets.

Because of evidence of plasma flow on the lower wing trailing edge and elevon landing edge tiles (wing/elevon cove) at the outboard elevon tip and inboard elevon, the low-temperature tiles are being replaced with fibrous refractory composite insulation (FRCI-12) and high-temperature (HRSI-22) tiles along with gap fillers on Discovery and Atlantis. On Columbia only gap fillers are installed in this area.

[Grammy]

My father in law worked at a research lab as a ceramic engineer doing various projects. Obviously his work on the tiles was back in the late 60's or early 70's (?). I don't know precisely, because he took his security clearance very seriously and never spoke much about it. I only know about it because my husband told me he had seen the tiles when his dad worked on them.
We also never found out until a few months before he died that he had worked on the Manhattan project. Even though the project was long since declassified, he never spoke about it. That was a man of principle.

[maham]

I understand that the C-9 coating used on the AFRSI was developed by Rockwell International for NASA. Is this coating technology patented? If so what is the number? Is it available for license?