SpaceX made history Tuesday afternoon when it launched its new Falcon Heavy rocket carrying an electric car bound for deep space and returned two of three 15-story boosters back to Earth for perfect vertical landings. The initial test launch of what is now the world’s most powerful operational rocket marks the latest milestone in billionaire Elon Musk’s quest to send humans to Mars and eventually colonize the red planet. That Tuesday’s launch at 3:45 p.m.