The day of the accident, Jess is in the backyard with a chainsaw, clearing space to build the greenhouse she's always wanted. And, as always, she is thinking of Arthur. Arthur, her colleague in the botany department, who never believed she'd actually start the project. Arthur, who, after getting too close, has cut off contact, escaping to study the subarctic pines. But now there has been a disaster, connected to her husband's space tourism company: the explosion of a space shuttle filled with commercial passengers, igniting a media frenzy on her family's doorstep. Jess's engineer husband is implicated, and she knows there is information he's withholding, even as she becomes an unwitting player in the efforts to salvage the company's reputation. Struggling, Jess writes to the only person she can be candid with. She writes to Arthur. And in her e-mails -- warm, frank, yet freighted with regret and the old habits of seduction -- Jess tries to untangle how her life has changed, in one instant but also slowly, and how it might change still. With sure pacing and intimate wisdom, God is an Astronaut unfurls a story of secrets and of wonderment, the unforgettable and the vast unknowable.