Starfleet
In the fictional world of the Star Trek television series, books, and video games, Starfleet is the group that manages space exploration.  From the second half of the 22nd Century through at least the 25th Century, Starfleet is a part of the United Federation of Planets, a political group of planets with intelligent life, including Earth and Vulcan.  Members of Starfleet come from many different planets and are from many different species.  Though the mission of Starfleet is peaceful exploration of space, the group is also responsible for defense of Federation planets.