The Security Threat Hundreds of Miles Above Our Heads

What would happen if a nuclear weapon detonated in space, destroying the satellites that make so much of our digital existence — and our national security — possible? In this episode, William Hennigan, the lead writer for Times Opinion’s At the Brink series, speaks with the man whose job is to make sure that never happens. Thoughts? Email us at theopinions@nytimes.com .