Sample, Heat Shield, Mercury, MA-7

This fragment of the ablative heatshield of Aurora 7, the Mercury spacecraft M. Scott Carpenter flew on May 24, 1962, demonstrates the impact of reentry into the atmosphere from orbit. Each Mercury spacecraft featured a gently curved heatshield with a diameter of 203 cm (80 in) and a radius of curvature of 305 cm (120 in). Heatshields protect by creating a shock wave in the thin upper atmosphere that holds the superheated gas away from the spacecraft, creating a somewhat cooler boundary layer. An ablative shield’s material chars, melts, and sublimates, carrying away the remaining heat, protecting the spacecraft. The charring demonstrates the impact of temperatures of nearly 1100 C (2000 F) degrees during a reentry at a velocity of over 27,000 km/h (17,000 mph) from low Earth orbit.

NASA transferred this fragment to the Smithsonian in 1967, along with the spacecraft.