The mechanical and electronic devices of the station operate under extremely challenging conditions. Lubricating these devices to ensure the smooth operation of moving parts is also a formidable task, because if a grease loses its lubricating capacity due to the extreme weather conditions, important devices can be damaged or fail.
On behalf of the Alfred Wegener Institute for Polar Research, the Bavarian company Baader Planetarium installed a robotic observatory at the Dome C station which has been in provisional operation since 2009 when its housing, the AllSky dome, was put in place. Once it is in full operation, the purpose of the installation will be to investigate the distribution of human induced chemical pollutants in the atmosphere. The observatory dome can be opened 180 degrees and must allow fully automatic operation under extreme weather conditions, which is a particular challenge with regard to material, motors, reduction gearboxes and electronics. All mechanical components with altogether approximately 200 lubrication points must be lubricated according to the special low temperature requirements to ensure trouble-free operation of the observatory. Applications include the mounting system of the telescope with all its focusing devices, CCD camera equipment as well as the bearings of the observatory dome, which should open and close using a minimum of power due to energy scarcity in this extreme environment. The AZ 2000 Antarctica mounting system successfully passed all cold-chamber tests and will be transported to the station during the next "Antarctic summer".
As the low-temperature greases on the market had only been tested and specified for temperatures down to minus 65 degrees Celsius, Baader conducted extensive cold chamber trials with ten special greases from different manufacturers with regard to their suitability for use at temperatures beyond their specified temperature range. It turned out that most speciality lubricants harden under these conditions and lose their lubricating capacity.
"We had tested the low-temperature properties of our grease down to minus 65 degrees Celsius only, however, we had reason to believe that it would provide the necessary scope for trouble-free use at significantly lower temperatures due to its chemical composition", explains Dr. Wolfgang Sammer from Klüber Lubrication. The belief turned out to be true: the only lubricant complying with all requirements was Barrierta KL 092 by Klüber Lubrication. The special grease remained pasty, even at minus 80 degrees Celsius and low humidity, and yet maintained its good lubricating capacity.
Intense long-term cooperation
Several years passed between the first contact between Baader and Klüber Lubrication and the commissioning of the observatory, due to the extreme weather conditions at the South Pole. There are only very few periods in which transport to or from the research station can be achieved. During the Antarctic winter months between February and November, transport is absolutely impossible for almost six months. As planes have not enough lift for high loads due to low air humidity, the distance of 2000 kilometres must often be crossed with crawler tractors. The unique conditions of the place, however, justify the enormous efforts: not only is the air particularly dry, clear and free from light pollution, the atmosphere is almost free from turbulence and therefore allows high-resolution astronomical observation.
Robotic control of the observatory is undertaken at Alfred Wegener Institute in Bremerhaven, Germany. Measurements are also analysed there. As maintenance and repair on site are subject to high costs, the special grease responsible for the installation's maneuverability has an important role to play when it comes to the permanent availability of both the installation and its instruments.
All lubrication points of the observatory had already been lubricated in Germany prior to their transport to Antarctica. As Barrierta special greases facilitate for-life lubrication, there is no need for maintenance or repair work on site.
"We have been using Klüber Lubrication speciality lubricants for years for many applications, for our optical equipment for example", says Thomas Baader, General Manager of Baader Planetarium. "Building an observatory dome for such extreme climatic conditions has been our most challenging project with regard to mechanics and temperature-resistant electronics so far. We are glad to have Klüber Lubrication as our partner, who has not only been able to provide us with a high-quality product but also with support during all planning and implementation stages."
Dome Concordia is a joint project of French and Italian Antarctic research with participation of the German Alfred Wegener Institute. The observatory is a permanent part of the research station and is to be equipped with further instruments on demand to conduct further research projects.
Klüber Lubrication's Barrierta KL 092 grease, which is applied at the South Pole-based observatory, is tried-and tested and stands out, like all Barrierta K greases, because of its wide service temperature range and good compatibility with plastics and elastomers. Also, at extremely low temperatures, Barrierta special greases remain smooth enough to avoid overload of low-torque drives. They are therefore suitable for the long-term lubrication of rolling and plain bearings requiring long-term stability under changing environments and low driving power.