Explanation

Hypersonic flight. Hypersonic flight is flight through the atmosphere below about 90 km at speeds above Mach 5, a speed where dissociation of air begins to become significant and high heat loads exist. Russia is the first country to deploy a hypersonic nuclear missile. The U.S. Defense Department tested a hypersonic glide body in a flight experiment conducted from the Pacific Missile Range Facility in Kauai, Hawaii, on March 19, 2020. The Navy and Army jointly executed the launch. (U.S. Defense Department)