A Starfleet vessel bound for Earth in 2364, chosen by Picard to carry three revived people from the late twentieth century back to their home planet.
The USS Charleston is a Starfleet ship named in the episode The Neutral Zone. In 2364 Data brings three frozen humans aboard the Enterprise from a derelict cryonics satellite, and Beverly Crusher revives and cures them.
The three, Claire Raymond, Ralph Offenhouse and L. Q. Sonny Clemonds, have slept for more than three hundred years and have nowhere to go. Once the Enterprise's confrontation with a Romulan warbird at the Neutral Zone is over, Picard tells them the Enterprise will meet the Charleston, which is headed for Earth.
The ship itself is not shown. It is the means by which the survivors start their new lives, Raymond having learned that descendants of hers still live on Earth.