The Outer Buoy: A Story of the Ultimate Voyage — Jan De Hartog

The sea captain is now retired, but adventure is still in his blood. The taste for excitement and the lure of the unknown have led Harinxma to crisscross the face of the earth many times, and they now draw him toward the only frontier left to him. With several of his old shipmates - all of them reaching the final years of their varied lives - Harinxma joins in NASA's exploration of the mysterious effects of space travel on the human soul.