Elon Musk is very pleased with how the latest SpaceX rocket prototype performed during the flight portion of a test flight in Texas Wednesday—but the landing portion shows there is plenty of room for improvement. The uncrewed 16-story SN8 prototype failed to slow down enough during its descent and exploded in a fireball when it hit the ground, the Wall Street Journal reports. "Fuel header tank pressure was low during landing burn, causing touchdown velocity to be high & RUD"—a rapid unscheduled disassembly, aka a crash—"but we got all the data we needed!" Musk tweeted. He added: "Mars here we come!"