Most Earth observation satellites are in polar orbits.
It's the sole reason of existence for the launch facility at Vandenburg AFB.

The object in the picture is NOT in a polar orbit, the existence of the picture itself proofs it.
Any object in a polar orbit would have swooped by at 7 klicks per second.
There are several pictures and they are more or less in focus, i.e. the object's orbit closely matches that of the Orbiter.
Most parsimonious explanation is that the object is something that came of the Orbiter.
I think it's rather small and close to the camera.
IOW space debris.
Just as the caption reads: [link to eol.jsc.nasa.gov]