A 52-meter spacecraft reentered the atmosphere at Mach 25, splashed down in the Indian Ocean, and then floated for 24 days while a recovery fleet chased it through rough seas to Christmas Island. SpaceX wants this thing back that badly. Here's why. Ship 40 is the first Starship upper stage in 13 flights to come back from space in one piece. Every previous reentry produced telemetry and debris. This one produced actual hardware. Engineers can now walk up to heat tiles that survived the real…