SpaceX has launched the 15th test flight of its massive Starship rocket from Texas in what could become a landmark moment for the future of spaceflight. The mission is designed to test whether Starship can complete a full round trip to orbit and return to the exact launch site from which it lifted off. If successful, it would mark a major step toward Elon Musk's vision of a fully reusable rocket system capable of dramatically reducing the cost of reaching space.