The spacecraft would instantly become, if it successfully gets off the ground, the most powerful rocket on Earth.
The two-stage rocketship, standing taller than the Statue of Liberty at 394 feet high, was due for blastoff from the SpaceX facility at Boca Chica, Texas, during a two-hour launch window that opens at 8 a.m. EDT .
"Success is not what should be expected," Musk told a private Twitter audience on Sunday night, saying the best-case scenario would provide crucial data about how the vehicle ascends to space and how it will fly back to Earth. On Sunday night, Musk said,"it's more likely" for the flight to be postponed than to launch on Monday. SpaceX has backup launch windows on Tuesday and Wednesday for roughly the same times.Both the lower-stage Super Heavy booster rocket and the upper-stage Starship cruise vessel it will carry to space are designed as reusable components, capable of flying back to Earth for soft landings - a maneuver that has become routine for SpaceX's smaller Falcon 9 rocket.
In February, SpaceX did a test-firing of the booster, igniting 31 of its 33 Raptor engines for roughly 10 seconds with the rocket bolted in place vertically atop a platform. After separating from the Starship, the Super Heavy booster is expected to execute the beginnings of a controlled return flight before plunging into the Gulf of Mexico.