THERMAL PROTECTION

Thermal protection was definitely one area where the Russians heavily benefited from US experience. Like the Shuttle Orbiter, Buran was largely covered with black and white silica tiles, with reinforced carbon-carbon (RCC) protecting the nosecap and the leading edges of the wings. Ceramic reusable surface insulation was developed in

the 1960s by Lockheed long before the beginning of the Shuttle program, but had to compete with other thermal protection design concepts such as replaceable ablator panels and metallic heat shields before it was eventually chosen for the Shuttle. There was also an alternative idea from Rockwell to use mullite tiles made from aluminum silicate. Therefore, the use of silica tiles on the Shuttle was certainly not a foregone conclusion when research on the Space Shuttle began in the late 1960s. Reinforced carbon-carbon was developed by Ling-Temco-Vought (LTV) for the Dyna-Soar project in the early 1960s.

Although the Myasishchev design bureau did some research on foam ceramic insulation (in cooperation with the All-Union Institute of Aviation Materials) for its spaceplane projects in the early 1960s, there are no indications that the experience gained was passed on to the Buran team. Although the US experience was readily available when work on Buran began in 1976, the Russians still needed to develop their own techniques to process the required raw materials and manufacture the tiles. As Gleb Lozino-Lozinskiy later recalled, it was initially believed that the quartz sand from which the fine quartz fibres for the tiles were made was simply not available in the Soviet Union and would have to be imported from Brazil, but that eventually did not turn out to be necessary [13].

Buran’s thermal protection system (Russian acronym TZP) had an overall mass of 9 tons and was designed to protect the vehicle’s aluminum skin from the very low temperatures in Earth’s shadow (down to — 150°C) to the extremely high temperatures encountered during re-entry (up to +1,600°C). The temperature of the aluminum skin was not allowed to be lower than —120°C or exceed +160°C and shouldn’t be any higher than +50°C prior to the beginning of re-entry. These conditions needed to be met in order for Buran to make a total of 100 missions. Buran had five types of thermal protection: white tiles, black tiles, felt material, carbon-carbon, and thermal barriers.