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  Space Shuttle tiles: black and white for a reason?

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Author Topic:   Space Shuttle tiles: black and white for a reason?

Posts: 1049
From: County Down, Nothern Ireland
Registered: Feb 2002

posted 02-11-2015 06:41 AM     Click Here to See the Profile for ASCAN1984   Click Here to Email ASCAN1984     Edit/Delete Message   Reply w/Quote
Were the space shuttle tiles black and white for a purpose, e.g. the distribution of heat, or were they just for design?

The reason I ask is most other spacecraft with tiles used seem to have the same design.

David C

Posts: 1014
From: Lausanne
Registered: Apr 2012

posted 02-11-2015 07:56 AM     Click Here to See the Profile for David C     Edit/Delete Message   Reply w/Quote
Yes, for heat rejection. To simplify: white is good for reflecting heat back and black is good for radiating heat away. The expected heating mechanism and temperatures determine what the best solution will be. The black (and RCC) portions are where you would expect the highest shock-wave/plasma heating loads. The white, the much lower mainly solar radiation loads. Note that the standard X-15, together with the Mercury and Gemini cabins (not the aft heatshield domes) were non-ablative and pretty much black for the same reason.

This is less important for ablative coatings because they employ a different heat rejection principle. Hence Apollo type CMs had silver/ silver and white layers over their ablative coatings for in-space thermal control prior to re-entry. The long term thermal load distribution on Skylab mission CMs being different to Apollo missions as (amongst other factors) the PTC roll was not possible whilst docked to the orbiting workshop for months.


Posts: 1966
From: Atlanta, GA
Registered: Feb 2007

posted 02-11-2015 02:27 PM     Click Here to See the Profile for garymilgrom   Click Here to Email garymilgrom     Edit/Delete Message   Reply w/Quote
From my book on the Thermal Protection System:
NASA used two categories of Thermal Protection System tiles on the Orbiter — low and high temperature tiles. The surface coating was the primary difference between these two categories.

High-temperature tiles used a black borosilicate glass coating and covered areas of the vehicle in which temperatures reached up to 2,300F. Low-temperature tiles contained a white coating with the proper optical properties needed in areas of the vehicle where temperatures reached up to 1,200F.

...the HRSI tiles are made of a low-density, high-purity silica 99.8-percent amorphous fiber (fibers derived from common sand, 1 to 2 mils thick) insulation that is made rigid by ceramic bonding.

...there are two different densities of HRSI tiles. The first weighs 22 pounds per cubic foot and is used in all areas around the nose and main landing gears, nose cap interface, wing leading edge, RCC/HRSI interface, external tank/orbiter umbilical doors, vent doors and vertical stabilizer leading edge. The remaining areas use tiles that weigh 9 pounds per cubic foot.

...the LRSI tiles are of the same construction and have the same basic functions as the 99.8% pure silica HRSI tiles, but they are thinner (0.2 to 1.4 inches) than HRSI tiles. The thickness of the tile is determined by the amount of heat the tile encounters. The LRSI tiles are manufactured the same way as the 99.8% pure silica HRSI tiles, except the tiles are coated to be optically and water resistant (the coating is about .010 in. thick). The coating is made of silica compounds with shiny aluminum oxide to enhance and obtain the best optical properties possible.

Excerpt From: Gary Milgrom. "Space Shuttle Thermal Protection System." Gary Milgrom, 2013. iBooks. You can find this book for free in the iTunes Bookstore here.

TPS Cover V2 sml


Posts: 33
From: England, U.K.
Registered: Jul 2011

posted 02-11-2015 04:28 PM     Click Here to See the Profile for Rowland   Click Here to Email Rowland     Edit/Delete Message   Reply w/Quote
I would love to get a copy of this book but don't have an iPad. Is it available in any other formats?

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