I always thought of a reentry vehicle compressing the air in front of it. And that would cause a lot of heat kind of like filling my tires. But I keep hearing friction even from nasa heat shield experts. OK, I guess maybe 10% of the heat is friction. I always assumed they said that to make the concept easier. But I’ve heard it so much recently that I’m starting to think I’m wrong. Or maybe they’re the same thing in a way that I hadn’t understood yet. Can you straiten me out?