The ablator itself is a unique blend of cork wood, binder and many tiny silica glass spheres. It was invented for the heat shields flown on the Viking Mars lander missions. A similar technology was used in the first US manned space missions Mercury , Gemini and Apollo . It was specially formulated to react chemically with the Martian atmosphere during entry and carry heat away, leaving a hot wake of gas behind the vehicle. The vehicle slowed from 19,000 to 1,600 km/h (5,300 to 440 m/s) in about a minute, producing about 60 m/s 2 (6 g ) of acceleration on the lander and rover.