At the end of the first orbital test flight for its 164-foot Starship, SpaceX envisions a reentry into the atmosphere at speeds approaching Mach 25, or 19, 000 miles per hour, followed by 15 minutes of hypersonic flight. During this time, the spacecraft will hurtle sideways, generating tremendous heat before adjusting to an upright position for a "soft " rocket-powered ocean landing 62 miles north of Kauai. It will sink in the Navy's Pacific Missile Range Facility, according to plans for the historic flight, and join dozens of warships that have gone down over past decades during Navy "sink exercises...