USS Pathfinder is an ongoing e-mail roleplaying game/collaborative work of fanfiction, set in the Star Trek universe in the early 25th century (a couple of decades after the events in the movie Star Trek Nemesis).
Originally founded as 'Star Trek Frontier Fleet' in the year 2000, the combined adventures of the USS Calhoun, USS Odyssey, USS Arakov, USS Valkyrie, Pandora Station, USS Atlantis, and Yeager Colony, have led us to the USS Pathfinder where our adventures continue.
When the USS Voyager returned home with valuable data collected in the Delta Quadrant, Starfleet was able to develop an experimental transwarp drive. Initially, only the USS Calhoun (launch date: May 5, 2390) was equipped with one of these new transwarp engines, together with a small number of new transwarp-capable Arrow-class shuttlecraft. In the same year, a retrofit of the Prometheus-class USS Epimetheus with a transwarp drive was started at Pandora Station, and the Talaxian-built Deep Space Delta One starbase was brought online in the Delta Quadrant.
The transwarp experiments with the Calhoun and Epimetheus turned out to be a success, and on August 26, 2391 Starfleet announced a fleet of transwarp vessels: the Frontier Fleet, consisting of the USS Calhoun (Sovereign class, NCC-78546), USS Epimetheus (Prometheus class, NCC-74914), USS Atlantis (Akira class, NCC-83548), USS Odyssey (Intrepid class, NCC-71832-A), USS Valkyrie (Prometheus class, NCC-78603), and USS Solstice (Nova class, NCC-72724). This new fleet's mission would be to explore the uncharted areas of the Milky Way galaxy.
After the loss of the Odyssey and the destruction of the Valkyrie in early 2400, Starfleet launched the newly constructed (and transwarp-capable) Vesta-class USS Pathfinder (NCC-98503) on July 1, 2400.