How does society develop in the Astra?
What do the Astrans find at Alpha Centauri?
How long do they stay there?
Where do they go after that?
Do some opt to stay and found a colony?
Do they encounter aliens?
Meanwhile, what is happening in the Solar System?
Are other interstellar craft launched?
If so, to where?
Many of Poul Anderson's works end with the vista of a vast future stretching ahead, even those that are set in the past. At the end of The Corridors Of Time, the Bronze Age is coming.