For anyone surprised when a used heat shield looks scorched and pitted: that's the point. An ablative shield is designed to char and erode, carrying heat away with the material it loses. A pristine one after reentry would be the alarming photo.

So it's a shield that works by being sacrificed. Like a pan you're supposed to burn.

Pretty much. Which is also why ablative shields aren't reflown. You can inspect one, learn from it and put it in a museum, but you can't send it up again.

I could look at photos of returned hardware all day. The surface of a used heat shield is somewhere between burnt toast and a geology field trip.

Crème brûlée from across the room, satellite photo of a desert from up close.

Pedantic note: people say capsules 'burn up' from friction, but most of the heating comes from the air in front of the vehicle being compressed. The shield spends reentry sitting behind a layer of extremely hot gas.

Thank you. I have been correcting people about this at dinner parties for years and have stopped being invited to dinner parties.

Compression is the main term, though friction isn't zero. This is the point in the thread where someone links a textbook and we all learn the word 'stagnation'.