How does the psychological environment of a Mars mission differ from Antarctic bases?

Mars crews have no ability to be evacuated in an emergency

While Antarctic bases provide data regarding isolation, they are fundamentally different because individuals at those locations can step outside into a breathable atmosphere and can be evacuated if an emergency occurs. In contrast, a Mars crew lives in a small, pressurized space with no safety net, facing the reality that Earth is an unreachable dot in the sky. This creates a unique and profound psychological toll, as the crew must cope with total isolation and the knowledge that immediate assistance is impossible.