SpaceX's new Starship rocket explodes minutes after launching on its first test flight, crashing into the Gulf of Mexico.The nearly 400-foot rocket carried no people or satellites, but was supposed to go on a round-the-world trip and eventually land in the Pacific.Throngs of spectators watched from South Padre Island as the rocket began to tumble and explode just four minutes into the flight.SpaceX CEO Elon Musk had warned that the rocket might not reach space, and the company plans to use Starship for moon and Mars missions.