Polar Exploration

Navigation relies on precise timekeeping. When at sea, a marine chronometer ensures that captain, navigator, cook — and the ship’s electronic and other systems — all tick to the same beat. It is no different on a research vessel. Claus-Peter Lieckfeld sailed with the Polarstern in Antarctic waters. He describes the importance of knowing the exact time on board.

Time is all about measure and rhythm. When those factors are missing, we experience it as something viscous and unreal. This is what happens when, for example, there is no alternation between day and night. On board the Polarstern, the research vessel of the Alfred Wegener Institute, I need to set my own rhythm. In the cabin shared with photographer Ingo Arndt, I draw the bleached curtain when my watch tells me it’s time to go to sleep. Beyond the cabin porthole, the huge expanse of pack ice to which we are moored continues to gleam in the late December sun. Here, in the Weddell Sea, off the coast of the Antarctic Peninsula, it is spring, and as bright as day virtually around the clock. Only around midnight does the sun dip toward the edge of our frozen world and set the ice on fire as it briefly touches the horizon.

Craggy ridges — formed where the autumn seas have herded drift ice together to create our home of pack ice — now look like miniature mountain chains. Watery cracks ramify into a system of fiords; on the icecap itself, snowdrifts assume the aspect of Saharan sand dunes by moonlight. The illusion is perfect, so long as there are no scientists, no emperor penguins, no seals to spoil the picture with an untimely reminder of scale. It is one o’clock in the morning, at a latitude of 67.8° south. A perfect time for dreaming.

Ever since the Polarstern has been moored to the ice, I take a timeout around 1.00 a.m. It’s then that I go to the bridge and daydream — or “night-dream”, which amounts to the same thing here. It all begins with a blissful loss of orientation and ends in a state of absolute serenity. At this hour, the only other person on the bridge is the officer on watch. He has to keep an eye on the ice, as some of the scientists are taking advantage of the twilight to proceed with their outdoor experiments. This includes a Belgian- Dutch-French group, which is monitoring, through a couple of meters of pack ice, which trace gases support the exchange between the icy waters and the atmosphere.

The duty officer lends me powerful binoculars. From the almost 30-metre-high bridge, I can see the group moving slowly across the ice. “They’re running to their own time…,” I muse. Perhaps their pulses are racing — it’s hard work trudging through deep snow. The Nansen cargo sledges slew under the weight of so much equipment. A week earlier, our Ski-Doo snowmobile gave up the ghost. Since then, researchers have had to pull the sledges themselves, just like Fridtjof Nansen.

Naturally, there must be some objective measure of time on board — one which is absolutely sure, and can’t be stretched, even though that would be handy when transmitting huge volumes of data back to the University of Leiden. And one that can’t be compressed either, even if there is an inevitable feeling of homesickness after months on end in this white wilderness.

Aboard the Polarstern, a master clock from Wempe shows Coordinated Universal Time (UTC), which is definitive for the whole vessel: not only for “Slushy” in the galley, whose job is to ensure regular mealtimes, and for the captain on the bridge, who needs to know when the watch is up, but also for the ship’s own communications network, which sets the time for all the computers and equipment connected up to it. This system makes it possible to log commands to the second and also enables researchers to synchronize their own, system-independent watches with UTC before they leave the vessel.

Ice and snow as far as the eye can see, and the sun never sets. The only shadow is cast by the Polarstern

In addition, the marine chronometer from Wempe is the reference clock for one of the most demanding of all the major experiments being conducted on this Polarstern expedition — namely, the experiment to determine the movement of ice in the Weddell Gyre. Scientists already have a general idea of how ice circulates in this huge clockwise vortex in the Weddell Sea: initially in a northerly direction, along the Antarctic Peninsula that points towards Cape Horn, then eastwards along the Drake Passage, before heading back south to the coast of Antarctica. Entire icebergs are pulverized in the process. At the same time, the winter covering of sea ice is not only melted by the summer sun but also broken up by the sea’s currents. But how precisely does this happen, and to what extent?

Between 28 November and 2 January, GPS measurements continually chart the precise position of the Polarstern, which is moored to its section of pack ice. By the second half of December, the vessel’s movements resemble nothing so much as a wild lurching backwards and forwards. The assembled scientific minds on board conclude that there must be times when the power of wind and undercurrents counteracts and even reverses the gigantic forces of the Weddell Gyre for a short time. This is what explains why the sea becomes free of ice so rapidly in the relatively warm summer months. In other words, it is not so much an unrelenting force in one direction as a chaotic mix of sometimes opposing forces that crushes the ice and thereby increases the rate at which it melts. This phenomenon of rapid melt is familiar to aficionados of the cocktail hour: Crushed ice in a margarita melts much more quickly than blocks of the stuff in a scotch on the rocks.

We are gifted with a graphic example of this just after the exchange of gifts on Christmas Eve. The night has more or less flown by when, following the renditions of “Silent Night” in 12 different languages, a glance at the ship’s clock through the mists of mulled wine tells me: “Three o’clock, high time to hit the hay … tomorrow, you’re planning to take a look at David Thomas’ experiments … and David is an early riser.” Suddenly, however there is a whiff of unease in the “Blue Salon”: The ice is breaking up! And breaking up fast enough to endanger the expensive finemeshed nets used to catch krill for research purposes. A nighttime rescue — in full sunlight, of course — comes too late. Before anything can be done, the net has slipped to the seabed, several thousand metres below the vessel.

Our world has cracked. Despite it being Christmas Day, David Thomas, an expert for flora and fauna in the Southern Ocean, is out and about bright and early. Fortunately, his experiments are on a segment of pack ice that hasn’t broken off. He kneels in the snow and makes busy with some long glass capsules. In front of him are sheets of paper covered with scales and time diagrams. Before leaving the vessel, he synchronized his watch with the marine chronometer. David’s task is to find out how quickly tiny organisms from beneath the icecap react to ultraviolet light, and to discover what it is that protects fragile copepods, for example, against the aggressive UV radiation — whereas humans, by contrast, have to cream themselves with sunblock.

I walk to the edge where the ice has broken. Other inhabitants of the pack ice are also checking out the damage. Emperor penguins waddle over to inspect the break and some belly-flop right into the icy waters. The boatswain, meanwhile, has arranged for an inflatable dinghy to shuttle researchers to their claims on the other side of the newly created fiord. Among them are Gerhard Dieckmann and his team, who are anxious to see whether their sediment traps have suffered any damage. The latter are buoy-like contraptions, lowered by rope to a depth of 20 or 30 meters below the icecap, where they collect tiny nutrients that fall from the underside of the ice. The experiment also comprises a clock and a flow meter, so that the scientists can determine the time and type of current that prevails when specific substances sink to become a link in the food chain. If the clock fails, the data are worthless.

I am beginning to understand how important it is for science to have precise time parameters, particularly at sea.

In the Blue Salon’s bookcases, I find a Maritime Dictionary. The title of one chapter is “When Time Came Aboard”. That occurred around 250 years ago, when the first marine chronometer was made — a marvel of engineering, which also showed the time in the vessel’s home port. By then, it was already possible to work out the ship’s latitude by means of navigation instruments that used the stars — clouds or fog permitting. In the absence of precise knowledge of the time, however, it was impossible to determine longitude.

This state of affairs first changed with the advent of the marine chronometer, an example of precision timekeeping that Wempe has been producing in perfected form for many years now — and for a host of craft, ranging from cruise liners to our very own Polarstern. Oblivious to heavy seas or other perturbations, such a timepiece shows the exact time of a particular geographic location — as a rule, Greenwich, in south London. A comparison of local time with Greenwich Mean Time serves to determine longitudinal position: A time difference of four minutes corresponds to one degree of longitude. Today, navigation equipment using the satellite-based global positioning system (GPS) provides positional data to an accuracy of a couple of meters, whether on land, at sea, or on pack ice.

The expedition leader takes the decision that the experiments on the other side of the cracks are too difficult to reach and therefore orders the evacuation of the remainder of our ice floe. Soon afterwards, the Polarstern has tied up at another location — from where the broken pieces of drift ice are seemingly no easier to reach. Now it is clear that our time on the ice is running out. One and a half more weeks of research, and then it is time for the voyage home. By then, the section of pack ice that the Polarstern abandoned at 67.23° south, 55.25° west is a mere fragment of ist original size. But in reality nothing has disappeared. It just seems that way.

Marvels of Precision: Master and slave clock systems from Wempe

The master clock controls the slave clocks by means of an electrical pulse or a data message. As a rule, the master clock is connected to a GPS device and uses GPS time as the time standard. It is also equipped with an extremely precise quartz oscillator, so that it can record the time accurately when operating in autonomous mode — in the event that the GPS signal should fail.

Left: GPS synchronization
Center: Master clock 20097, Interfaces to Automaten systems
Right – from top to bottom: Digital slave clocks, Analogue slave clocks with second hand (UTC), Intelligent analogue slave clocks (LT)