The United Earth Space Probe Agency, commonly abbreviated UESPA, was an organization centered on Earth responsible for the exploration of space.
UESPA evolved, in part, from the United Earth AeroNav Forces of the early 21st century. In 2067 , the agency launched the Friendship One probe toward the Delta Quadrant, as part of a series of unmanned exploration.
By the 2130s the United Earth Starfleet had taken UESPA's place as Earth's leading exploratory agency, but the two would continue to cooperate. UESPA personnel would also aid in the construction of the Enterprise (NX-01) in 2150. UESPA would continue to help control Starfleet vessels into the 2260s. James T. Kirk would report the destruction of the USS Anatres to UESPA. Kirk would also inform John Christopher that UESPA was the USS Enterprise's operating authority.
In one alternate timeline the IKS Qu' was a UESPA vessel prior to capture by Klingons. In another alternate universe, UESPA became a purely military organization after several other powers established the Interstellar Coalition. They also operated the UESS Enterprise in the 2260s.