This object in the Air & Space Museum is probably not photographed very often.
This is a mock-up of the lunar retroreflector arrays that were left on the moon
by three of the landings in the 1970's. Lasers from Earth were bounced off of these
arrays and the distance to the Moon (and its orbit) was established to an accuracy of
a couple of inches. Also determined was the fact that the Moon is slowly pulling away
from the Earth. Macpurity never worked with this data, but knew quite a few people who did.