One of the most innovative aspects of the Mars Pathfinder and Exploration Rover missions were the durable airbags which helped the spacecraft survive a hard landing on the surface of Mars. Instead of having to slow their descent from parachute speed, they could carry much less fuel... and bounce. But developing the airbags was a significant engineering challenge. How to create a fabric that could survive a long fall, across sharp rocks, which wouldn't clog up the lander when it deflated. Engineer Tommaso Rivellini explains the journey to create the airbag system which became so successful.