Shuttle silica ceramics black tiles, were mostly air and so fragile that you can break, crush them with the force of your hands (quote from NASA documentary). They were usually damaged by ice in upper atmosphere during ascend and from some old quora post potentially by micrometeoroids, space debris in space and heat during reentry. In 1996 they were introduced new stronger black tiles https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20120016878.pdf but because problems with their weight and heat conductivity they were used only on some parts of the Orbiter. These new tiles could survive ascend ice impact without any damage (there is picture in link above page 11, how they look after 3 flights vs old tiles) but someone here at Space Stack-Exchange wrote that non of Shuttle tiles survive more that 10 flights. Also from NASA documentary, during reentry Shuttle must survive not only lot of reentry heating, but also lot of aerodynamics pressure.
So my questions are:
- If those early silica ceramics black tiles were so fragile how can they survive AD pressure during reentry? Did shockwave protect them from direct impact?
- How much more were 1996 tiles resistant to material damage than the old black tiles and why they didn't survive more than 10 flights?
- Was a material damage of tiles only result of impact of Ice in upper atmosphere during ascend or also debris, micrometeoroids impact in orbit and reentry heating, reentry AD pressure during descend?
- How much effect each of this factors could have?