SpaceX's newest version of its massive Starship, the world's largest and most powerful rocket, is now scheduled to launch its critical test flight no earlier than Thursday, May 21, at 6:30 p.m. EDT (2...

SpaceX got within a half-minute of launching its newest and biggest Starship on a test flight Thursday evening before a cascade of problems halted the countdown.

“For those who think this is simply another repeat test flight, the engineering changes under the rocket ‘hood’ are substantial,” Joseph Gonzalez, an associate professor of practice in aerospace engin...