A heat shield protected the two-astronaut Gemini spacecraft against the enormous heat of reentry into the atmosphere, which began at a velocity of more than 27,500 kms (17,000 miles) per hour. Like those of other early human spacecraft, Gemini's heat shield derived from ballistic missile warhead technology. The dish-shaped shield created a shock wave in the atmosphere that held off most of the heat. The rest dissipated by ablation -- charring and evaporation of the shield's surface. Ablative heat shields are not reusable. Picture taken at the National Air and Space Museum's Steven F. Udvar-Hazy Center in Chantilly, Virginia, USA.
<a href="//commons.wikimedia.org/wiki/User:Sanjay_ach" title="User:Sanjay ach">Sanjay Acharya</a>
<span class="int-own-work" lang="en">Own work</span>