Recorder-marker from the SS Valiant
A log buoy or recorder-marker is a recording device carried by starships. In the event of imminent destruction or capture, a recorder-marker is designed to relay all the starship's data back to its command base. The recorder-marker is built to withstand the complete destruction of a starship, with a minimal possibility of external forces causing damage to the data held within. (Star Trek II: The Wrath of Khan)
The SS Valiant carried a recorder-marker on its mission in 2065. When the vessel was destroyed crossing the galactic barrier, the recorder-marker was ejected, and remained adrift for two hundred years, when it was picked up by the USS Enterprise. Despite the damage done to it by the long exposure to space, most of the data was still retrievable. (TOS: "Where No Man Has Gone Before")
Federation starships also carried recorder-markers. During the encounter with the Fesarius, Captain Kirk ordered the Enterprise's recorder-marker launched. Balok destroyed it almost as soon as it was launched. (TOS: "The Corbomite Maneuver")
Data recorder
A data recorder or mission recorder was a device carried by starships similar to a log buoy or a recorder-marker. In the event of imminent destruction, a data recorder was designed to record all the vessel's data. The recorder was built to withstand the complete destruction of a starship.
In 2154, a data recorder was retrieved from the wreckage of the Andorian warship Kumari by the Template:ShipClass starship Enterprise NX-01. (ENT: "Babel One")
In 2369, Commander Benjamin Sisko told Lieutenant Jadzia Dax and Chief Miles O'Brien to take a runabout and find the mission recorder of the destroyed Klingon Template:ShipClass attack cruiser IKS Toh'Kaht. (DS9: "Dramatis Personae")
Emergency buoy
An emergency buoy in 2370
An emergency buoy is a device launched from a starship designed to send information back to the starship's command authority. This can include logs or other information. Such a device is usually used if the starship has no time to use its communications system, or if it anticipates being destroyed before it can do so.
In 2370, Doctor Beverly Crusher gave the order to launch an emergency buoy to notify Starfleet about the Borg. (TNG: "Descent, Part II")
Apocrypha
The novelization of TAS: "One of Our Planets Is Missing" (in Star Trek Log 1) refers to the captain's log of the Template:ShipClass USS Enterprise as having the capacity to be shot clear of the ship and being "permanently mounted in a special, super-fast courier torpedo equipped with a powerful homing beacon."