The 55 scientists and technicians from 6 different countries are there to investigate the changes in the Arctic. Hence the name of their expedition: TransArc - Trans-Arctic survey of the Arctic Ocean in Transition.
I have translated one part of the press release that I found of particular interest:
Schauer was in the central Arctic for the last time in 2007 and this time around has found an ice cover that is similar to the one in the year that went into the history books as the year with the lowest sea ice cover since satellite measurements in 1979 began. The first ice thickness measurements confirm this: in 2011 as well as in 2007 most of the ice has an ice thickness of 0.9 m. In comparison, most of the ice in 2001 was measured at 2 m. That year total sea ice extent at the end of the melting season corresponded to the long term average.
This is the third time the Polarstern reached the North Pole. On September 7th 1991 it did so with the Swedisch research icebreaker Oden. Almost exactly 10 years later, September 6th 2001, there was a joint expedition with the American USCGC Healy.