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The two ships’ scientific crews want to better understand the changes in the Arctic sea ice and the associated ecosystem. Accordingly, both ships will employ very similar, in some cases identical, sensors and methods. Nevertheless, the two platforms are very different in terms of their size and type. As Martin Schiller, a sea ice physics engineer at the AWI who will be on board Tara Polar Station, explains:

Generally speaking, everything on Tara Polar Station is one scale smaller than on the Polarstern, which carries around 100 people. At the same time, of course, this also minimises Tara’s own influence on the measurements taken and the environment.

For the team on Tara Polar Station, everything is new: It’s their first test in the sea ice. “We hope that the team on board can implement all the long-planned concepts well. We will then see how well the various systems and workflows already work. Above all, it will be exciting to see how Tara Polar Station will operate in the sea ice,” explains Marcel Nicolaus, project partner in the Tara Polar Station team and the chief scientist on RV Polarstern. On RV Polarstern, the work will benefit from many years of experience in the Arctic, among the scientists and the ship’s crew alike.

Tara Polar Station – built for two decades of drift studies in the Arctic sea ice

Built by the France-based Tara Foundation, Tara Polar Station was designed to drift across the Arctic Ocean ten times over the next 20 years. The ship was christened in Lorient, France, in April 2025 and then prepared for its first deployment this summer. It will carry out its first full drift from summer 2026 and will then be on site for a full year.

The scientific programme aims to better understand the effects of climate change in the Arctic and the rest of the planet. The work is based on the collaboration of an international and interdisciplinary consortium of more than 30 institutes. Together they will analyse the consequences of melting sea ice and pollution on the unique and fragile Arctic ecosystems, monitor Arctic fish stocks, and ideally discover new species and processes.

Measuring 26 metres long and 11 meters wide, the station looks a bit like a flying saucer – and its missions can be compared to those involving the International Space Station (ISS). The team on board, the “Taranauts”, will gather a wide range of readings and observations for the many scientists and institutes at home. Though the scientific and technical requirements are highly diverse, the central questions are:

• What are the long-term responses of the central Arctic ecosystem to climate change?
•  How is biology influenced and modified by the sea ice?
•  How do the oceanographic, biodiversity and biogeochemical cycles in the central Arctic Ocean work?
•  What are the most important microbial and climatic feedbacks in the Arctic atmosphere?
•  What contaminants and pollutants can be found in the central Arctic Ocean and how are they changing?

First experiences with the ROV and moonpool

Tara Polar Station has what is known as a moonpool, located in the centre of the ship: a circular shaft with a diameter of two metres that offers direct access to the ocean from the large wet lab at the heart of the ship. The moonpool also allows oceanographic equipment and remotely operated vehicles (ROVs) to be deployed below the sea ice. Martin Schiller is already looking forward to using the new ROV “Ann” with this moonpool: “I’m very curious to see how the moonpool performs in regular use with our ROV. It will probably be a huge relief if we don’t have to spend a lot of time physically sawing a hole in the sea ice before each dive.” Creating these holes in the sea ice, especially in winter, and then keeping them free of ice is an enormous effort. In addition, the scientists on board will receive their samples and equipment back much more safely and conveniently. The ROV was installed on the ship in spring (Figure 3) and has since successfully completed its first dive in the harbour basin (Figure 4). The first real deployment under the Arctic sea ice will now follow – with great anticipation. This experience gained working with a moonpool in the ice will also be very valuable far beyond Tara Polar Station, e.g. with regard to future work with Polarstern’s successor.

In addition to the ROV programme, the team will take many other measurements in the atmosphere, on and in the sea ice, and in the ocean over the coming weeks. The crew will also test how the platform can be manoeuvred and positioned in the ice.

The team has already cleared one major hurdle: the crossing from France via Norway to Spitsbergen. According to Martin Schiller, who observed this part of the expedition from home: "The platform reached Longyearbyen on Svalbard safely and quickly, which speaks in favour of the seaworthiness of the design. However, this voyage in the Arctic Ocean remains a real challenge due to the ship’s particularly flat and very wide hull. I expect the Tara Polar Station to continue to experience heavy ship movements when travelling in open water.” The focus in the coming weeks will now be on the work in the sea ice. The team will be measuring ice thicknesses, examining meltponds, taking water samples, launching weather balloons, analysing air samples, and much more – just like on the RV Polarstern, only on a smaller scale. To do this, the various laboratories on board need to be set up, the samples processed, and data management procedures established.