Early during Star Trek: The Original Series the term "Starfleet Command" hadn't been invented. In some early episodes, the Enterprise's operating authority was referred to as the United Earth Space Probe Agency, abbreviated as UESPA and pronounced "YOU-spah." The term "Starfleet Command" was coined around the middle of the first season and has been in use ever since. The term UESPA fell into disuse and was largely forgotten, but this emblem suggests that UESPA might have been a division of Starfleet.