Though the Traité d'Unification creating the United Earth Republic was not signed and ratified until 2130 (TNG novel: Articles of the Federation), the agency was in existence as early as 2067, when the unmanned interstellar probe Friendship 1 was launched towards the Delta Quadrant under UESPA's auspices. (VOY: "Friendship One")
- The Starfleet Museum continuity asserts that UESPA was founded in 2064. (The Starfleet Museum: Museum Timeline)
UESPA was formed from NASA, ESA and other national space agencies sometime after World War III. (Orion Press: "Lexicon, U-Z", 2010 revision) Its precursor organization was the International Space Agency, which had subsumed many national agencies -- but not NASA -- as early as the 2030s. (VOY: "One Small Step")
- The Indonesian Space Agency (Star Trek: First Contact novelization) was a separate entity from UESPA, at least in 2063, when they would have paid any price to acquire Zefram Cochrane's warp drive.
Cargo ship UES Baikal was modified to carry a short-range subspace communications system and a 100-metre-diameter antenna in 2146. This ship was intended to serve as a mobile command platform supporting United Earth Space Probe Agency operations. (The Starfleet Museum: Baikal Class and Marconi Class)
Prior to the founding of the Federation, UESPA and the Earth Starfleet worked jointly to administer the NX Project as well as the first warp-5 capable ships such as Enterprise (NX-01). (ENT: "First Flight", "Demons")
- In The Starfleet Museum continuity, UESPA and the United Earth Star Fleet merged to form the United Earth Stellar Navy (UESN) in 2151. (The Starfleet Museum: Museum Timeline)
- It may be that at least the five founding members of the United Federation of Planets each had its own space-exploration organization and each contributed funds to Starfleet as well as supported their own survey efforts. (Orion Press: The Plumber's Helper)