The starship Valiant, now relocated to Earth orbit, prepares for a visit from a group of Human ambassadors. Tensions between the crew explode after a horrifying reality of Human military technological achievement comes to light. Book 2 of what I suppose is a Codename Alpha series. Since this is book 2, it may be worth your time to check out the previous, which is just called Codename Alpha. It isn't needed, but it may give you some added context.

A disaster aboard the starship Valiant leaves the crew stranded in orbit of an alien planet's moon, and an expedition to the planet takes a turn for the worst when they find the planet is inhabited by aliens that don't take kindly to their arrival.