The United Earth Space Probe Agency is an organisation within the Federation tasked with deep-space exploration. While initially independent, it was merged with Starfleet Command sometime before 2143.
By the 22nd century UESPA and Starfleet combined their efforts, with UESPA personnel assisting in the design of Starfleet vessels. The last known UESPA-operated vessel was VK Velikan, launched in 2160.
It is unknown whether UESPA still operates in the 24th century and beyond.