Log buoy

A log buoy, also known as a recorder-marker or an emergency buoy, was a type of space buoy that could be launched by starships.

A recorder-marker was designed to relay the ships logs and other relevant information back to its command base. Recorder markers were launched in situations when a ship could not use its communications system to relay the information before the imminent destruction or capture of the ship. The recorder-marker was built to withstand the complete destruction of the starship at close range, with a minimal possibility of external forces causing damage to the data held within. 

Starships as well as other smaller craft also carried a data recorder also known as a flight recorder or a mission recorder, where the same data was stored. The recorder was built to withstand the destruction of the ship, so that it could be salvaged from the wreckage after the destruction of the craft. 

Data recorder
In 2154, a data recorder was retrieved from the wreckage of the Andorian warship Kumari by the starship. 

In 2368, data from the flight recorder of Wesley Crusher's downed Academy flight trainer was examined by a Starfleet Academy board of inquiry to determine the cause of a fatal accident involving the Nova Squadron flight team. 

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 attack cruiser. 

Log buoy
The Earth vessel SS Valiant carried a recorder-marker on its mission in 2065. When the vessel was destroyed after the encounter with the galactic barrier, the recorder-marker was ejected, and remained adrift for two hundred years, before it was picked up by the USS Enterprise (NCC-1701). Despite the damage done to it by the long exposure to space, most of the data was still retrievable. 

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. 

In 2285, Saavik ordered the launch of the log buoy of the Enterprise before ordering all hands to abandon ship, in her Kobayashi Maru exam. 

In 2370, Doctor Beverly Crusher gave the order to launch an emergency buoy from the USS Enterprise (NCC-1701-D) to notify Starfleet about the Borg. 

Logbuchboje Enregistreur de vol