They consist in buoyant capsules which store a sampling of the data recorded by the station and of the control parameters allowing to check the good operation of the system. After being released from the station, the messengers get to sea surface in order to deliver their information.

Two types of messengers are used:

  • the expendable messengers (memory capacity 30 Kbytes) are released automatically when their memory is full. After reaching the sea surface they repetitively transmit their data during one month through the ARGOS system, while drifting freely at sea surface.
  • the storing messengers (memory capacity 40 Mbytes) are released by an acoustic order sent from a ship standing at the vertical of the station. After having hauled it aboard, one extracts the inside data storage electronic board readable on PC.

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 expendable (left) and storing (right) messengers

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 expendable messenger and connecting cable (after a 6 month aging test in sea water)

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the 5 messengers fitted on the station