Return from space is a challenging and dangerous endeavor. At velocities five to ten times greater than a speeding bullet, a space capsule entering a planetary atmosphere must decrease its kinetic energy to near zero before impacting the ground. Where does much of this energy go? The answer: thermal energy. Because of this, space vehicles require robust high-temperature hypersonic materials to protect them from hot plasmatic flow that envelopes the vehicle during entry. This image depicts the testing of a basic high-temperature hypersonic material: solid graphite. A hemispherical sample of graphite was subjected to a high enthalpy plasma air flow under vacuum at the von Karman Institute for Fluid Dynamics in Belgium. This material, which is normally black in color, is heated to temperatures as high as 1,600⁰C, causing the hemisphere to radiate a beautiful deep orange color, providing vibrant contrast with the light purple plasma air. These experiments help engineering researchers understand the material’s behavior to extreme conditions that will be experienced during atmospheric entry, and thus inform the design of future spacecraft. The field of hypersonic materials is heating up and opening new opportunities to explore and understand our universe.
