Julian Allen pioneered and developed the Blunt Body Theory that made possible the heat shield designs that were embodied in the Mercury, Gemini, and Apollo space capsules, enabling astronauts to survive the fiery reentry into the Earth's atmosphere. A blunt body produces a shockwave in front of the vehicle-visible in the photo-that actually shields the vehicle from excessive heating. As a result, blunt body vehicles can stay cooler than pointy, low-drag vehicles.

Credits - NASA