The Neptune Class Frigate was the first starship class designed by Starfleet, based on the successful breaking of the Warp 2 Barrier by the NX-Project in 2143.  The Neptune Class, nicknamed the "Day Frigate" since the ship was primarily designed to operate only within Earth's solar system, utilized existing technology of spaceships operated by the United Earth Space Probe Agency as well as a basic weapons array designed in the early 2140s by the Starfleet Tactical Studies Division.  The first four Neptune class starships were ordered in 2144, with a projected construction of all vessels by the end of the decade.