SpaceX's plan to colonize Mars, explained

Elon Musk gave the biggest talk of his life in Guadalajara, Mexico, where he detailed his plans to set up a self-sustaining colony of 1 million people on Mars. He knows the rockets and spaceships he wants to build, but many questions still need to be answered if he wants to pull off such an ambitious feat. The Verge's Loren Grush breaks down some of the challenges with input from Bill Nye (CEO of The Planetary Society) and Will Pomerantz (VP Special Projects, Virgin Galactic).