Most of the debris will return to earth on their own. Although they are in stable orbits, they still do get some drag from the uppermost extents of the atmosphere and their orbits wobble slightly from the earth moon and sun gravitational system.
Just it can take anywhere from a few months to a few thousand years for this to happen, depending entirely on the exact path of the object in question.
Also that's odd. Because the tiles on the bottom of the shuttle are clearly black in color in photographs, although that may just be their surface color and the ceramic they are made from is white inside.
But that image is tagged as STS-61-C. STS-61 itself replaced portions of the Hubble Telescope, and we may be looking at pieces of that which were discarded.
Alternately, STS-61-C was just a routine deploy satellites and do experiments flight.
Either one could easily have photographed a passing piece of debris. Large chunks like this are relatively rare still, but do from time to time pass near active structures.