PS93.2 Weekly Report No. 4 | 10 August until 15 August 2015
With High Tech into the Deep Sea
[14. August 2015]
This is the fourth and final weekly report from a technically and logistically very challenging expedition to the LTER (Long-Term Ecological Research) observatory HAUSGARTEN.
Beside the “traditional” gears we use for our multidisciplinary time-series work like water samplers, plankton nets, grabs, moorings and free-falling systems, we also operated a deep-diving Work-Class Remotely Operated Vehicle (ROV), an Autonomous Underwater Vehicle (AUV), different Unmanned Aerial Vehicles (UAVs), partly also in autonomous flight modus, and – not to forget – the (manned) helicopter of “Polarstern”. The ship was packed with all sorts of larger equipment and sometimes the moving of gears back and forth on the working deck to have single ones ready for deployment reminded us on the good old computer game TETRIS – now it’s paying off that we spent so much time on playing this game.
A new feature during this expedition was the combination of various high-tech instruments in single missions. For instance, for investigations to analyse the interaction of physical, chemical, and biological processes at the melt water front separating less saline waters surrounding melting ice flows and water masses of the open ocean exhibiting higher salinities, we used the ship, the AUV, and a helicopter in parallel. The ship’s salinometer was used to detect the frontal system and to monitor temporal variations, the AUV crossed this zone several times thereby conducting all sorts of measurements at different water depths and took water samples on the way, and two camera systems mounted on the helicopter were used to assess the structure of the melting ice flows in the study area. The entire mission took almost 11 hours and provided an extremely interesting huge data set to be analysed during the next weeks.
However, the expedition was not only used to apply existing and proven technology, but also provided the scope to test new developments. Within the frame of a large national project (ROBEX – Robotic Exploration of Extreme Environments – ROBEX), bringing together the expertise of space and deep-sea research, we deployed a prototype pressure housing made out of concrete (!). This may sound a bit bizarre, because there are well-proven pressure housings made out of steel or titan, however, these vessels are generally rather expensive. Therefore, to save money, we always look for alternatives - and finally found another option. Of course, for the new pressure housings we cannot use “normal” concrete, which you can buy in a customary DIY store. To increase the pressure resistance of the new vessels this concrete was blended with silica flour. After some positive tests in hyper pressure chambers on land, we now deployed one of these housings in a free-falling system (bottom-lander) at 2500 m water depth to test their suitability in long-term expositions. We are already very excited how the pressure chamber will look like, when we recover it next year, when we will return to HAUSGARTEN observatory.
On Wednesday, August 12th we finished our scientific work and set sail for Tromsø, where this expedition will come to an end on August 14th in the late evening. During the cruise, we collected numerous samples and obtained a vast amount of physical, geochemical and biological data, which will extend our time-series at HAUSGARTEN observatory and finally help to understand the effects of Global Change induced environmental changes in the Arctic Ocean.
We would like to thank Captain Thomas Wunderlich and his crew for their hospitality, the great teamwork and the pleasant atmosphere on board, and gratefully acknowledge the support by the HeliService team during our expedition.
We are now looking forward to see our families and beloved friends at home, and we hope that there are some warm summer nights left after our return.
With best wishes from board Polarstern,
Thomas Soltwedel
Contact
Scientific Coordination
Rainer Knust
+49(471)4831-1709
Rainer Knust
Assistant
Sanne Bochert
+49(471)4831-1859
Sanne Bochert
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» Weekly Reports Polarstern » Research Vessel and Icebreaker Polarstern » Polarstern Meteorology