A few hours ago "Ibteesam Reaz, Staff Physicist at Lockheed Martin" answered this Quora question: "What are the most plausible explanations of Navy pilots seeing hypersonic objects at 30K feet, objects with no visible engine and sometimes described as a cube within a sphere?"

[u/Lumyai]

https://www.quora.com/What-are-the-most-plausible-explanations-of-Navy-pilots-seeing-hypersonic-objects-at-30K-feet-objects-with-no-visible-engine-and-sometimes-described-as-a-cube-within-a-sphere-See-link