PC-focused content ahead. The following article or section describes content from the perspective of the PC version of the game. While the mechanics will be similar for players on Xbox and PS4, many elements of the UI will be different. Please consider updating this article to include content from the console versions of Star Trek Online.
The Mission Journal is a menu accessible by clicking the Starfleet, Klingon, or Romulan emblem next to the overview map in the top right of the game UI.