Explorer S-55 in orbit
Explorer S-55 was a Terran satellite that was in service to NASA in the latter half of the 20th century. An image of this satellite was stored in the library computer of the USS Enterprise. This image was later retrieved by the Talosians during their survey of the library computer's contents in 2254. (TOS: "The Cage")
The satellite Explorer S-55 was destroyed when its booster rocket failed in 1961. Though this satellite failed, the program was notable for its scientific discoveries, including the finding of the Van Allen Belt.