The Columbia Accident Investigation Board announced today that the foam theory was the “most probable cause” of the space shuttle tragedy. Based on analysis from tons of Columbia debris, they believe there is compelling evidence that a large chunk of foam fell off the fuel tank on launch and cracked a critical heat shield on the shuttle’s wing. Upon re-entry several days later, hot air flowed inside the wing and melted metal braces, and eventually tore the wing off – the entire shuttle came apart moments after that. The investigators are working on their final report, which is due in July.