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The measures taken to curb the coronavirus pandemic are affecting the MOSAiC expedition too, complicating participant changeovers for the various legs of the voyage. Powerful ice movements also present a major challenge, keeping researchers constantly on their toes.


On an expedition, you always need to be prepared to deal with the unexpected, as the team aboard the research vessel "Polarstern" in the Arctic now know only too well. The participants in the voyage’s second leg were actually supposed to be replaced back in mid-February, but with thick ice slowing the progress of the icebreaker "Kapitan Dranitsyn", which was carrying the new personnel to the "Polarstern", the changeover was delayed by more than two weeks.

Ice movements are currently the biggest challenge faced by the expedition’s researchers. Stormy weather meant that large rifts kept opening in the ice and the floe, which initially had an area of almost one square kilometre, has now broken up into several pieces. As a result, the researchers often have to spend their time rescuing equipment, reconnecting power and data cables and finding new, accessible locations to take measurements and samples. However, the fast-changing conditions have their advantages too: they provide an opportunity for fascinating new research into such subjects as the formation of new ice in rifts and gullies and the subsequent snow accumulation.

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Snow dunes, characteristic elevations and grooves, have been forming in the snow since mid-January.
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Wind speeds of up to 20 metres per second brought movement to the ice: At the beginning of March, a crack up to 10 metres wide formed, which ran under the "Polarstern" and made areas of the ice floe inaccessible. With the help of a helicopter, important measuring instruments could be recovered from the other side of the crack.
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Meanwhile, the icebreaker "Captain Dranitsyn" brought the previous crew of the "Polarstern" back to Tromsø. The participants saw the sun again after months of darkness.
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On the way the "Captain Dranitsyn" had to be refuelled by another icebreaker, which took several days. After three and a half weeks of sailing, she finally moored in Tromsø again on 1 April.
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Amy Macfarlane (in front) is a PhD student at SLF and one of the participants of the third leg of MOSAiC who have been on "Polarstern" since the beginning of March.
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Amy is taking a snow sample from a frozen crack. Since parts of the floe have broken off and drifted away, new places for measurements have to be found.
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As the ice is in constant movement, an extensive system of channels and crevasses has formed. When ice is compressed, characteristic elevations, so-called press ice ridges, form.
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A mosaic expedition in the truest sense of the word: the floe breaks into smaller and smaller pieces. This keeps the researchers on their toes: what will the surroundings look like the next day? Which installations have to be secured? Where can we even work on the ice?
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8100 eggs, 1360 kg potatoes and 86 glasses of Nutella were eaten by the expedition members of the second leg of the journey in two and a half months. The "Polarstern" kitchen team provides three meals a day as well as coffee and cake. Good food lifts the spirits and is also necessary, because working outside in cold and stormy weather burns many calories.

The personnel involved in the second leg of the voyage are now finally back on dry land. Their return trip from the MOSAiC ice floe took three and a half weeks. Their ship had to be refuelled by another icebreaker en route as it would not have had enough fuel for the journey otherwise. They finally docked in Tromsø, Norway, on 1 April. From there, the returning participants flew to Bremen on a charter flight and are currently on their way back to their home countries, though their ability to travel there depends on the measures taken by the relevant countries to combat the coronavirus outbreak. SLF researchers Martin Schneebeli and Matthias Jaggi, who had been in the Arctic since December 2019, are now safely back home in Switzerland.

The coronavirus pandemic had already required adjustments to be made to the planned course of the MOSAiC expedition. For instance, the situation resulted in the cancellation of the first aerial survey campaigns to take atmospheric and sea-ice measurements, which were meant to leave from Norway’s Svalbard archipelago in March. The next personnel swap is expected to be delayed by a few weeks too. The changeover was initially supposed to take place by means of a flight from Svalbard, but Norway is no longer allowing people to enter its territory because of the coronavirus, making a voyage by ship from Tromsø impossible too. Alternative plans for the next personnel switch are currently being drawn up. However, before it can take place, the quarantine rules will need to be applied and the new participants will need to undergo two tests for Covid-19. No one on board the "Polarstern" is currently infected with the virus.

Press release of the Alfred Wegener Institute, 24.04.2020: Alternative resupply plan for Polarstern now in place