21 July 2025 – A very successful sea campaign has been conducted at the KM3NeT ARCA site in the past two weeks. During this operation 18 new detection units and a new acoustic long baseline positioning system were installed.
ARCA has thus been enlarged to include 51 deployed detection units, which are connected to shore through a network comprising two long-distance electro-optical cables and 5 submarine junction boxes.
The new acoustic positioning system is a state-of-the-art solution for high-accuracy positioning measurements in the deep sea. Three acoustic beacons mounted on autonomous structures were installed during this campaign and set up into operation together with the previously installed beacon. Their position was then measured with sub-meter precision. The new system will be used in connection with the triangulation system already in operation in order to improve the absolute position and orientation of the telescope, allowing to push its pointing accuracy.
The operation was conducted in two hitches, sailing from Malta. The Optimus Prime vessel, equipped with a work-class submarine vehicle (the ROV – Remotely Operated vehicle), was used. The ROV has a crucial role in all deep-sea operations, including: assistance with the deployment of the detection units on the sea floor at the target position and with the correct orientation; connection of the units to the submarine junction boxes; inspection and measurement of the positions of the deployed structures; operation of the release mechanism which allows the detection unit to unfurl from the launcher vehicle. The operation was carried out by Fugro-Derinsu, in collaboration with Observe for operation of the ROV and with the support of EXAIL for installation of the new acoustic system.
The large amount of activities which were accomplished and the efficiency during all phases, mark a new performance record in offshore operations for KM3NeT.
The operation also marks a very important step towards completion of the KM3NeT4RR project, financed in Italy by MUR (Ministero dell’Università e della Ricerca).
The whole Collaboration extends its gratitude to the offshore and onshore teams whose hard work made this campaign a big success.
