KM3NeT - ORCA sea campaigns

Liveblogs during sea campaigns for ORCA.

Two more successes in the construction of ARCA and ORCA

9 October 2026 – The KM3NeT Collaboration is celebrating a period of intense and highly successful marine operations, with two more significant steps performed last week for ARCA and ORCA.

ARCA: CTF3 installed

During a marine campaign conducted by Alcatel Submarine networks, the Cable Termination Frame 3 (CTF3) was installed at the ARCA deep-sea site. This high-tech node serves as a vital junction connected to the end of the second branch of ARCA’s second main electro-optical cable to serve the second building block of the apparatus. CTF3 is equipped with 4 Medium Voltage Converters to regulate the high-voltage power delivered from shore to the level required by the offshore network, and is designed to distribute power and data through 16 electrical and 16 optical wet-mateable connectors.
Welcome, ARCA CTF3!

ORCA: A fight against environmental conditions to reach ORCA44
Meanwhile, at the ORCA deep-sea site, in spite of unstable weather conditions, a sea campaign was conducted to deploy new detection units and perform maintenance operations on the submarine node and some acoustic devices.
At the end of the operation, ORCA reached a configuration with 44 detection units installed.
Welcome, ORCA44!

Sonar map of the deep-sea installations at ORCA at the end of the operation, comprising two nodes for submarine connections (marked N1 and N2), the Module Instrumented Interface (marked MII), which is a hub for connecting deep-sea instrumentation, and a total of 44 detection units (DUs) – those installed during the latest campaign are highlighted. Out of the field of view are the calibration base and the instrumentation unit connected to it.

The Collaboration wants to convey its deepest gratitude to everyone involved in these important steps, in particular to the offshore and onshore crews during the operations. The ARCA team tackled this deployment immediately after an exhausting 17-day marine campaign, while the ORCA team maintained absolute focus through a tense, weather-delayed week.

Welcome, ORCA42!

8 July 2026 – A very successful sea operation took place during last week-end, leading to a new extension of the ORCA submarine telescope off the coast of Toulon, France.

During the operation, four new detection units were installed in the deep sea and connected to the detector in a record time of an average 8.5 hours of operation per unit.

Ancillary actions were also performed, including a deep-sea inspection of some detection units, recovery of one acoustic emitter of the positioning system which requires some maintenance and recovery of biofouling traps installed years ago which will provide new insights on how to preserve the transparency of the glass of the optical modules in the deep sea over very extended periods.

At the end of the operation, the apparatus comprises 42 detection units.

As usual, the operation was performed with two ships: the Castor 02 of Foselev, for deployment of the detection units, and the Janus II of SAAS (formerly Comex), equipped with the Apache deep-sea remotely operated vehicle (ROV), for submarine operations.

Many thanks to the crews offshore as well as to the team who performed the functional tests of the new detection units from the shore station and anyone else involved in making this great step forward possible!

Welcome, ORCA42!

Sonar map of the deep-sea installations at ORCA at the end of the operation, comprising two nodes for submarine connections (marked N1 and N2), a calibration base (CB) connected to an instrumentation unit (IU), and a total of 42 detection units (DUs) – those installed during the latest campaign are marked.

Welcome, ORCA-38!

20 April 2026 – A very successful sea operation took place last week, leading to a new extension of the ORCA submarine telescope off the coast of Toulon, France. Read more

Welcome, ORCA33!

15 October 2025 – A very successful sea operation took place last week, leading to a significant extension of the ORCA submarine telescope. Read more

Second node of ORCA installed

13 August 2025 – Last week we installed a second submarine node for the ORCA neutrino telescope. It is an important step in preparation of the next deployments of detection units for ORCA.

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4 new detection units installed in ORCA

16 May 2025 – This week at the ORCA site, a sea operation was performed with a twofold purpose: the recovery from the sea bottom of some oceanographic instruments which required some maintenance and the installation of a set of 4 new detection units. The number of detection units in ORCA has thus been increased to 28. Read more

Welcome ARCA33 and ORCA24!

28 October 2024 – The latest sea campaigns at both the KM3NeT’s ARCA and ORCA sites have led to major progress in expanding detector installations and improving calibration systems.

The number of detection units in operation in the deep sea has been increased to 57: 33 in ARCA and 24 in ORCA.

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ORCA enlarged with four new detection units

15 June 2024 – A new marine operation took place in the last week for enlarging the ORCA deep-sea neutrino telescope.

Taking advantage of a spot of good weather of 48 hours, four new detection units were added to the apparatus.

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Three more detection units for KM3NeT/ORCA

1 May 2023 – During a two days sea operation, 27-28 April 2023, three detection units were successfully connected to the ORCA detector of KM3NeT in a record time of just over 24 hours. In addition, an acoustic beacon was recovered for battery replacement. The total number of deployed ORCA units is now 18, as visible in the sonar scan above.

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