Warning buoy
A warning buoy, also referred to as a warning beacon or a marker beacon, was a type of space buoy that could be deployed to maintain position in space and transmit a repeating message warning about something nearby. (; et al.) On the hulls of Federation starships, marker beacons were bright strobe lights, intended to aid other ships in visually locating that vessel. ()

Uses
In 2154, Captain Jonathan Archer left a warning beacon in orbit of an M-class planet that hosted a Klingon garbage site to warn others of the very lethal silicon-based virus one could find there. ()

In 2266, the  encountered a cube-shaped warning buoy at the border of First Federation space. These buoys were designed to follow any ship approaching their space and emitted lethal radiation to force the approaching ship to destroy the buoy. This action would prompt the First Federation to initiate contact. ()

In 2268, the USS Enterprise encountered a Melkotian warning buoy stationed at the border of Melkotian space to keep intruders from approaching their homeworld. ()
  
In 2365, the 's marker beacons were activated by Lieutenant Worf as part of an ongoing medical quarantine. ()

In 2367, Captain Jean-Luc Picard ordered a warning beacon to be placed in orbit of Tarchannen III to warn others of the invisible species there. ()

In 2368, after the pocket of null space was mapped in the J'naii system, Worf devised the plan for deploying warning buoys around the pocket. ()

In 2375, Captain Kathryn Janeway had warning beacons placed around the telepathic pitcher plant, a bioplasmic organism that feeds on starships. ()

In 2376, Captain Janeway ordered a warning buoy to be placed in the Tarakis system, to warn others of the synaptic transmitter that was in use as a memorial there. ()

See also
Log buoy

External link

de:Warnboje
Communications technology