As soon as the Polarstern had dropped anchor at an ice floe, a small city appeared on the surface of the ice. Though the MOSAiC researchers don’t live there, it is where they conduct much of their research.
And they do so using a carefully planned structure: just as blacksmiths, potters and other artisans each had their own district back in the Middle Ages, in the ‘Ice Camp’ meteorologists and climate researchers, marine biologists and specialists for snow, sea ice and other disciplines work together in smaller camps of their own, which are also home to the specific equipment they need.
The German research icebreaker Polarstern will be the home of all MOSAiC participants during the drift. Besides being the living and working platform, Polarstern serves various other purposes, making it the central hub of MOSAiC:
- All laboratories, workshops, and offices are located on board
- Technical installations on almost all decks help to monitor the environment and perform various measurements
- The bridge and the crow’s nest serve as observational platforms
- The helicopter deck serves as hub for many flight operations
- All main winch systems are installed on and operated from the vessel
- Sample and cargo storage is centrally located on board
As a first preparatory step, the researchers set up the various stations of the Ice Camp, laying out a network of paths between them and installing power lines from the Polarstern to supply electricity to the stations as well as data cables to transfer all collected data back to the ship. When it comes to answering the call of nature, researchers can go to the toilet tent and relieve themselves using sealed bags, which are collected every night for disposal on board the Polarstern. Artificial lights would influence the ecosystem both on and below the ice, which is illuminated only by the moon and the stars during the Polar Night. This is why researchers will determine a large dark zone, in which they have to rely on infrared light exclusively to enable the observation of natural conditions with as little interference as possible.
One research centre on the ice is called ‘ROV City’, which hosts a broad range of scientists from various disciplines, ranging from sea-ice researchers to marine biologists and oceanographers, and also serves as the central platform for their measurements and dives. Of course, the researchers themselves don’t normally dive under the ice. Instead, they use remote-controlled or ‘remotely operated vehicles’ (ROVs). These unmanned vehicles are roughly box-shaped and measure ca. 80 X 80 centimetres. Thanks to a cable, they can transmit high-resolution video and a wealth of observational data back to the ice floe. Since ROVs are self-propelled, pilots can maneuver them to virtually anywhere they wish to explore. In many cases, they sweep vertically or horizontally along the ice margin, where they measure the characteristics of the water and ice.
In this way, marine and ice biologists can collect water samples, use the ROV’s cameras to observe organisms below the ice, or even use nets to collect them for further study at the ice camp or on board the Polarstern. Whereas research ships most often rely on a multibeam echosounder to emit sound waves and use the reflected echoes to map the seafloor, ROVs send their sound waves upwards, allowing them to measure the contours and underside of the ice. This way, they share new images of the virtually unknown world below the ice of the Arctic Ocean with each dive.
Most of the measurements and work of the sea ice team are performed within a few kilometers distance from the Ice Camp close to Polarstern. Sea ice and snow cover properties are observed with a huge variety of methods, covering and mapping the interfaces to the atmosphere and ocean as well as many snow and ice properties. Although the main Ice Camp is installed on first-year sea ice that is able to support such a station, major efforts will be made to include as many sea ice and snow cover conditions, ages, and features as possible in the surrounding area: new ice, refreezing of leads, deformed ice, weathering ice, and melting ice. A freezer lab container is used to process snow and sea ice samples throughout the year.
Ocean City is all about sea water research. Here, researchers can use a winch to lower their measuring equipment through a hole in the ice and into the water of the Arctic Ocean, and haul water samples from the ocean’s depths to the surface. To keep the water from immediately freezing in the frigid air when it surfaces, the hole is surrounded by a several-metre-wide tent that is heated to a few degrees above zero.
On a clear day, Met City catches the eye thanks to its veritable ‘menagerie’ of sensor masts, which the meteorological researchers use to measure an extremely broad range of data, e.g. the physical state of the atmosphere, as well as energy, momentum and humidity fluxes. The atmospheric chemists also working there take a closer look at the composition of the air and fluxes of chemical species. Another tent serves as a hangar for the tethered balloons that stand continuously at about 2 km altitude above the research camp. These balloons directly measure the atmospheric conditions in unprecedented vertical resolution as well as the composition of the atmosphere and aerosols.
A runway of 1,800 metres, prepared on level sea ice by using a snow cat, will enable DC 3 polar aircraft to take off and land. This runway is essential for various airborne activities around the main camp. Its position will depend on local ice conditions, but a distance of below 3 kilometres to the ship is ideal.
Day by day, new ice will form, adding to the old ice floe the Polarstern is moored to. This will result not only in the research vessel quickly becoming trapped, but also in the floe constantly expanding. Because this new ice is of particular interest to the MOSAiC researchers, they will set up additional stations here to investigate conditions on and underneath the ice. Just like the old ice, these patches of ice that formed after the Polarstern’s arrival will have working areas established on them in which the researchers will collect or drill out samples from the various layers of snow and ice once a week.
In addition, the researchers use drones packed with scientific instruments to expand the observational area beyond the central ice floe and also to collect samples from different atmospheric layers above the ice. These samples are then analysed on the Polarstern or, after the expedition, in the researchers’ home laboratories on land. However, all this data is of little use to the researchers unless they determine precisely where it was gathered. On an ice floe that is relatively solid, but nevertheless drifting on the Arctic Ocean, a satellite positioning system alone simply isn’t enough. This is why, at the very beginning, the MOSAiC researchers defined certain reference points on the ice which they use to project a virtual net with a 100-metre grid spacing over the old and, later, the new ice, allowing the locations of the individual measurements to be precisely determined. The coordinates of these points will be continually verified via satellite positioning. Taken together, the two values will show precisely where on the ice floe - and in fact on the planet - each measurement was taken.
All research stations are located within a 700-metre radius of the Polarstern. To ensure that researchers can safely work there and use the rest zone during one of their infrequent breaks, a 360-degree infrared scanner mounted high on a mast on the Polarstern constantly monitors the horizon and the entire Ice Camp. A lookout on the ship’s bridge keeps a close eye on the readouts, and if he or she detects a polar bear approaching the central zone, all personnel at risk are immediately brought back on board to safety. In addition, tripwires have been installed all around the Ice Camp. If a polar bear steps on one, it automatically sets off a pyrotechnic device. Without harming the bear, the loud and unfamiliar sound is often enough to scare it off as experienced polar researchers know.
There are also six specially trained polar bear protection staff on board the ship, three of which continually patrol the ice, armed, during the team’s working hours on the ice. In addition, researches leaving the central zone always carry firearms for their protection. Since 1980, when the Alfred Wegener Institute began its research activities, researchers have seen more and more polar bears on the ice of the Arctic Ocean. Despite those innumerable encounters, they have never had to shoot a single polar bear – a tradition the MOSAiC expedition aims to continue.