The old Polar Duke didn’t finish her Antarctic adventures with the termination of the NSF charter however:
http://www.newzeal.com/theme/antarctic/PolarDuke.htm
She was converted to a pure Seismic Survey Vessel in 1998 and is still operating, now as the Duke belonging to Guardline and CGGV:
I surveyed the Polar Duke in Singapore in 2004, still with some of the original crews from her days with NSF on board and heard a lot of stories from that adventure.