On August 5, 2012, the world's attention was captured by the Mars Science Laboratory (MSL) landing. One of the key components in the multifaceted landing of the Curiosity rover safely on Mars was the Thermal Protection System (TPS), or heat shield, on the spacecraft carrying the rover. Sensors being added to the Mars Science Lab heat shield. Photo by NASA. The thing people remember most about the heat shield is when it popped off the spacecraft and flung like a frisbee across the Martian landscape, landing with a plume of dust. Measuring nearly 15 ft (4.5 m) in diameter, the MSL heat shield was the largest to ever travel to another planet. That may sound impressive, when it comes to entering an atmosphere bigger is not necessarily better. While more resistance can act as a natural braking system the trade off is enormous heat build up on the spacecraft. And we're talking serious heat here, 3360º F (1850º C), almost twice as hot as molten lava.