2051-2220

In "The Big Rain" in 2051, an Un-Man spies on Venus and, as a result, a UN fleet returns to end the planetary dictatorship. One UN marine who fights on Venus stays and settles down afterwards. In "The Snows of Ganymede" in 2220, that marine's great-great-grandson is Torvald Kruse, a rancher's son, who joins the Planetary Engineers. Thus, Poul Anderson's Psychotechnic History sketches (barely) a family history set against the backdrop of the future history but this is nothing compared with the same author's Technic History.

In the Technic History, Nicholas van Rijn's granddaughter, Coya Conyon, marries David Falkayn. We see Falkayn's mother and one of his brothers on Hermes. David and Coya have a daughter and a son born on Earth, a grandson born on Avalon and a remote but direct descendant, Tabitha Falkayn, also born on Avalon. Tabitha marries Christopher Holm, son of Daniel Holm and presumed descendant of Ivar Holm who was on Avalon during the colonization of the Coronan continent. Van Rijn also has a son who will become Grand Duke of Hermes, Falkayn's home planet. 

The Psychotechnic History is like a sketch of a future history by comparison with the Technic History.