What happens when a once-in-a-generation talent trades Olympic glory for a journey that’s taken more turns than a rollercoaster? You get Gable Steveson—a man who’s done it all, yet still has the world asking: is he done with the Olympics, or is there one more run in him? Olympic champ?

Sign up for CNN’s Wonder Theory science newsletter. Explore the universe with news on fascinating discoveries, scientific advancements and more.CNN  — President Donald Trump’s pick to run NASA, Jared Isaacman, made waves Wednesday by signaling his intention to create a new focus on Mars ...