While adventure paths are not new, they have not been done before in Traveller. So I thought I would take a few moments to explain exactly what an adventure path is, giving you an idea of what to expect.
First and foremost, an adventure path is a series of linked adventures. How linked are they and how dependent on the previous adventure are they? That is the important question; this is what really separates an adventure path from a campaign broken into multiple parts. Each adventure in the adventure path is a fully independent, stand-alone adventure. If you only ran one adventure in an adventure path, it would make sense all by itself. It has its own beginning at the start and its own ending. You don’t need to buy the next adventure to reach a climax of the story. The next adventure continues the story from the previous adventure, but it is also a stand-alone adventure.
Think of it as episodes of Babylon 5 or Buffy the Vampire Slayer. Each episode had a problem that the characters resolved by the end of the episode (or in this case, adventure). Each of those episodes flowed from one to the next, forming a greater story that culminated in a major climax at the end of the season (or here, the adventure path). But through it all, each episode was a stand-alone episode (except for the two-parters, but still, you get the idea).
Behind each adventure, we have some supplemental material. This supplemental material varies from issue-to-issue, but it always provides you with timely help for your game. For example, Prelude to War: The Rose of Death adventure sends some of its time on the planet Cornath. So if the characters do something that gets them into trouble (innocent look) and they need a place to hide, you can tell them that one of their contacts has a farm only 300 km from their current position. You can show the players the map and provide some details about the area. Some issues may have ships native the area. Others may have vehicles, allies, enemies, ideas for what to do between adventures, creatures, descriptions of organizations, and more.
In short the additional material in each adventure path helps you to run the adventure on the fly when (no if) your players decide to do something the adventure didn’t think of.