The USS Enterprise (XCV-330), previously the UESP Enterprise (7) and also the SS Enterprise, was the first spacecraft named Enterprise to be designated a starship. (ST references: The Making of Star Trek: The Motion Picture, Star Trek Encyclopedia)
The UESP Enterprise was originally built as a Starliner, a manned interstellar probe, by the United Earth Space Probe Agency in the mid-to-late 21st century, as one of Earth's earliest attempts at interstellar travel. It was the only one of its class to reach its destination of Alpha Centauri; all the rest were overtaken by recently developed faster-than-light spaceships. The Enterprise detected radio transmissions from that star system in 2039, confirming the existence of intelligent lifeforms there. However, physical contact between Terrans and Centaurians did not occur until the UNSS Icarus visited the system in 2048. (ST references: Star Trek Maps, The Worlds of the Federation)
The XCVs - Experimental Coleopteric Vehicles - were abandoned in the mid-2120's, in favor of starships which used Henry Archer's Warp five engine. (ENT - Rise of the Federation novel: Patterns of Interference)
Nevertheless, the XCV-330 Enterprise was still remembered as an enduring part of mankind's early space voyages, enough that its image was seen alongside the Phoenix at the 602 Club in 2143, and was displayed in Admiral Maxwell Forrest's office in 2154. (ENT episodes: "First Flight", "Home")
At some point in its service history, the Enterprise had a Trill crewmember. On more than one occasion, this crew person's dedication and determination had contributed to the success of a difficult mission. (ST reference: Ships of the Line)
- Ezri Dax recalls a Trill crewmember of the Enterprise, and it is implied that the Trill was one of Dax's hosts (either Lela or Tobin). However, it could just as well have been another joined or unjoined Trill who Lela or Tobin knew at the time.
Circa 2273, an image of this USS Enterprise image was briefly displayed in the recreation room of the Constitution-class USS Enterprise. This was considered to be only an early, unused prototype and mistakenly installed, however, and was replaced with one of the more famous Enterprise (NX-01). (TOS movie: Star Trek: The Motion Picture, TOS novel: Ex Machina)
This ship was originally designed by Matt Jefferies during the early pre-production stage of Star Trek. After the show was cancelled, the design was considered for use in a planned, but never produced, sci-fi television series by Gene Roddenberry. A portrait of the ship later appeared in Star Trek: The Motion Picture.
Star Trek Maps adopted the design for its Starliner ships. Spaceflight Chronology also based the Declaration-class of ships on this image, though these were a much later and a more advanced series of cruise-ships, with a slightly different design. Later, Star Trek: Enterprise artist Doug Drexler based the Vulcan Suurok-class on this image. Following this, the TOS novel: Ex Machina later said this ship was only an unused prototype based on Vulcan designs and that the portrait had been mistakenly installed. It was removed and replaced with one of the Enterprise (NX-01).
It is uncertain what the prefix in the ship's name should be. "USS" appears in the portrait seen in The Motion Picture), while "UESP" is used in Star Trek Maps and the Star Trek Encyclopedia gives an "SS" prefix. However, the USS Enterprise predates the Federation, and was not (originally) a Starfleet ship (the NX-01 was Starfleet's first Enterprise). The United States of America did still exist in 2143 and are the current users of the "USS" (United States Ship) prefix, although this does not conclusively make the XCV-330 American. It is possible that the ship received a new designation and registration, from UESP Enterprise (7) to USS Enterprise (XCV-330) or SS Enterprise during its lifespan.