Jürgen and Karl came home for a week’s vacation in June that year. I’d seen Jürgen for a few days around Adele’s funeral, but we were both so soaked in grief I’d barely looked at him then. This trip was different. In all those months we spent apart, Gisela learned to crawl and be terrified of strangers—she now cried whenever Jürgen tried to pick her up. And over those months apart, Jürgen changed too.

He was quiet, spending long hours alone in his study even though he was supposed to be taking a break. After a few days of this, I stood in front of his desk. He looked up from a blueprint and his gaze was hollow.

“We need to go for a walk and enjoy this beautiful summer day,” I said flatly, propping my hand on my hip. “I am going to put Gisela in the stroller. I’ll see you outside in a moment.”

He didn’t even try to argue. He heard in my tone that I would not be deterred. We began to walk toward the park, and when we reached it, I motioned toward a shaded bench beneath a large linden tree. There we sat side by side, and I turned Gisela around to face us. She eyed Jürgen warily.

“This last year has been very difficult, but the technology is more marvelous than even I dreamed it could be. The next prototype is the A4. This rocket will launch vertically, straight up like this.” Slowly, almost dreamily, he raised his hand. “It will ascend at an angle we’ve calculated with incredible precision—every movement stabilized and guided by a finely tuned gyroscope. After maybe a minute, the propulsion ends. Now this rocket is somewhere in the order of sixty miles straight up. Maybe it even comes near the edge of space. Isn’t that remarkable?”

“Sixty miles—”