What specific reusable material does Starship utilize for its aerobraking heat shield, contrasting previous NASA reliance on ablative shields?

Reusable metallic-ceramic tile shield

The thermal protection system for Starship represents a significant departure from historical methods used for atmospheric entry on Mars. Previous NASA missions, especially those focused on single-use landers, relied on ablative heat shields, materials designed to burn away gradually to dissipate heat during entry. Starship, however, is engineered for full reusability, necessitating a more durable solution. Therefore, it employs a reusable metallic-ceramic tile shield. While effective, this material faces unique stresses in the Martian atmosphere, which contains harsher conditions, including more free oxygen that could potentially cause degradation during the extreme aerobraking maneuvers.