The Profile Dossier: Franklin Chang Díaz, the Astronaut Who Wants to Get Humans to Mars

"My vision is a future for humanity where we will be completely free to pursue activities outside of our planet."

At 18 years old, Franklin Chang Díaz moved to the United States from Costa Rica. He didn't speak a word of English, but he had big ambitions for his life in America: Become an astronaut.

Growing up, Chang Díaz spent afternoons imagining that he had his own rocket ship. He would invite cousins to join his crew, and they would lie on their backs inside a l…