Before SpaceX became one of the most valuable companies in the world, it suffered three consecutive rocket failures. By 2008, Elon Musk had invested nearly everything he had. The fourth launch wasn't merely important—it was a matter of survival.

Washington's annual July 4 celebration typically draws hundreds of thousands of people, who this year will have to contend with stepped-up security, possible thunderstorms and temperatures that could top 100F (38C). Reuters, the news and media ...