What I do know about what happened after the USAP contract ended...at some point the owners, Rieber Shipping, converted it to a seismic research vessel and renamed it the Duke. It was assigned to a Rieber subsidiary, Exploration Resources, which was subsequently spun off into a separate company in 2005. Exploration Resources was acquired the same year by CGG, now part of CGGVeritas (SEC 6-K report documenting the Duke as part of the General Company of Geophysics (GCC) fleet and describing the spinoff and CGG acquisition. The vessel was renamed the CGG Duke...as such it was spotted in Wellington Harbor on 27 June 2007 (left, another photo from shipspotting.com). It was decommissioned in 2009 as described in this 2009 CGGVeritas annual report. (Note that Rieber Shipping (now GCRieber) subsequently commissioned a new and larger seismic survey vessel named Polar Duke).
The decommissioning didn't last long...the Duke was reflagged to the Bahamas in 2009, and is currently operated by Gardline CGGV, a joint venture between Gardline Geosurvey and CGG Veritas (January 2013 Wikipedia update). Here's the current GardlineCGG data sheet with floor plans...interestingly, it shows the vessel with a red hull.
History...here's the 1987 ITT/ANS brochure about the Polar Duke...compare the floor plans.