This book might be about women's lib or is it polygamy? Women need to play the main role in space travel and especially colonization. This SF series presents many issues to ponder and suggests some inventions needed for space travel. The series starts in today's world and through forced invention gets mankind into space colonization to save the human race. Most of the science presented is in some stage of development now. If you want to travel for months in space and then create a colony on an empty planet, you need more women than men. On a spaceship, or in a scientific laboratory, women can do what a man would do. The man may be better at leadership because women tend not to want to lead, but in reading this series you might agree with the author about the makeup of the crew. There are a number of morale issues. This fourth book in the series finds them meeting the Galactic Alliance which is not the intelligence that created SHIP. The Galactic Alliance is advanced scientifically, but not socially. Their worlds have been warring for years and were a threat to the human colonies as the Galactic Alliance threatened expansion. Demonstrations by SHIP show the Galactic Alliance that their technology is not nearly as advanced as SHIP and these demonstrations by SHIP make them afraid to mess with the human race that appears to them as far more powerful than their weak new colonies would suggest. SHIP and crew make it obvious to the Galactic Alliance that they don't have to fear the humans as long as they keep their distance from the colonies. Craig and his female crew find out that the Galactic Alliance had received back an Unmanned probe that had flown by Earth and picked up intelligent radio signals. This tells them that another visit to Earth is in order to see about the human survivors of the extinction event.