Talk about a "holy s***" moment for Elon Musk ... his SpaceX rocket exploded in a massive fireball -- and the thing is, it was all planned out that way! 

Here's the lowdown ... Musk launched his largest and most powerful rocket in history, called Starship V3, from Starbase, Texas, Friday night. The rocket was supposed to lift off Thursday, but the launch was scrapped due to technical issues -- remember, Nicki Minaj made a cameo that day at the base minutes before the launch was called off.

On Friday, SpaceX tried the test flight again, and this time it was a success ... with the journey lasting over an hour before the rocket splashed down in the Indian Ocean and detonated like a 12,000-pound bomb.

Check out the video ... it's totally wild stuff! The test flight accomplished its main objective, which was to test new pieces of hardware in the flight environment for the first time.

As for Nicki, she came back Friday to see the aircraft take flight ... sharing some vids of her at the base, joking around while quoting her hit, "Starships."