This side of the sculpture was not intended for major viewing. The sculptor did not spend as much time sculpting details on this side as he did on the left (viewing side). The wing on this side was not found in the excavations. The one on the sculpture is a modern carving based upon the preserved left wing.
This famous sculpture was discovered in 1863 on the Greek island of Samothrace—in the precincts of the Sanctuary of the Great Gods.
The piece was probably carved around 200 BC—of Parian marble— to commemorate a naval victory. It is 25 feet high and rests on the prow of a ship. "The statue's powerful forward-moving stride, swept-back wings and sophisticated drapery are clearly evident. The head and the right wing are missing." It is one of a small number of major Hellenistic statues surviving as an original!
For additional information see conveniently "Winged Victory of Samothrace" in Wikipedia.