I was a bit surprised to learn that the Buran used heat tiles looking very similar to that of the Space Shuttle. Considering its potential for military application, and the cold war period in which both the US Space Shuttle and Russian Buran were developed, was any of the heat tile technology ever classified as state secret? If so, how did the Russian space program end up with something so similar? Was any/all of the technology patented (which would account for public disclosure and availability of the necessary information to reproduce it)?
Apparently the technology wasn't even patented.
"Lockheed refused to file a patent, saying there was no market for it," Forsberg said. "It was put on the shelf and his research stopped for two years. Then interest from the shuttle program revived it."
As described in Heppenheimer's Development of the Space Shuttle, 1972-1981 Chapter 6, Thermal Protection, manufacture of the tiles is fairly simple. (I am sure the devil is in the details though).
A slurry of silica fibers of 1.5 micron diameter mixed with a collodial silica binder is pressed into rectangular molds, dried in a microwave oven, then baked in kilns. The resulting blocks were then shaped and coated with a reaction-cured glass coating.
(summarized by me)
The manufacture was simple enough that after Orbiter production ceased, replacement tiles were made in a small tile shop at Kennedy Space Center.
Picture from Wings in Orbit
Ancedotally, I don't remember any aspect of tile technology being treated as sensitive when I worked in the program. Detailed information is available in the Press Kit which was contemporary with the first launch.
Even though it occasionally launched military satellites from the Shuttle, NASA is explicitly civilian, created during the Cold War to demonstrate to the world our peaceful use of space for all mankind, etc, etc. Thus, they don't develop State Secrets.
(Military rockets that launch from Cape Canaveral launch from Cape Canaveral Air Force Station, which is next door to Kennedy Space Center.)
From the law authorizing NASA:
§ 20101. Short title This chapter may be cited as the ‘‘National Aeronautics and
§ 20102. Congressional declaration of policy and purpose (a) DEVOTION OF SPACE ACTIVITIES TO PEACEFUL PURPOSES FOR BENEFIT OF ALL HUMANKIND.— Congress declares that it is the policy of the United States that activities in space should be devoted to peaceful purposes for the benefit of all humankind.
(b) AERONAUTICAL AND SPACE ACTIVITIES FOR WELFARE AND SECURITY OF UNITED STATES.— Congress declares that the general welfare and security of the United States require that adequate provision be made for aeronautical and space activities. Congress further declares that such activities shall be the responsibility of, and shall be directed by, a civilian agency exercising control over aeronautical and space activities sponsored by the United States, except that activities peculiar to or primarily associated with the development of weapons systems, military operations, or the defense of the United States (including the research and development necessary to make effective provision for the defense of the United States) shall be the responsibility of, and shall be directed by, the Department of Defense; and that determination as to which agency has responsibility for and direction of any such activity shall be made by the President.