I work in the Earth Science and Solar System Exploration Division, which is a hodgepodge of many different areas. The best publicized is the Mars meteorites discovery. Every year people go to Antarctica to look for meteorites because they are easily found there sitting on the surface of the snow. Lunar Rock Curration is part of this division, also. The field I work in is Orbital Debris.
Orbital debris is all the bits of space junk in orbit.
This is done on computers using data collected from many different sources. One of our sources is the U.S. Space Command Catalog. This catalog has a record of everything found in space that can be tracked on ground radar. This includes everything 10 centimeters, or about 4 inches, in size. Because we can track it on radar, we can develop an orbit pattern for it.