The Planetary Surface Texture Laboratory (PSTL) allows researchers to investigate how soil-like materials on the surface of planetary bodies — called regolith — reflect light. By knowing this characteristic of the surface, researchers better understand the properties of remotely observed surfaces and, in turn, collect clues about the geologic processes that have shaped those bodies.
PSTL has a specialized camera called a polarimeter to measure the degree to which material samples cause reflected light to become polarized. By mounting the camera and a light source onto a goniometer — an apparatus that allows a person to vary the angles at which the sample is viewed and illuminated — scientists can simulate the conditions that a remote-sensing instrument on a telescope or on a spacecraft would experience while observing a planetary surface. Researchers can then glean information about the composition and texture of the material (including particle size, particle shape and porosity) by determining how the reflectance (or brightness) and polarization of the sample change with the illumination and viewing geometry.
The work conducted in the PSTL will prove particularly useful for interpreting data returned from the Korea Pathfinder Lunar Orbiter (KPLO) spacecraft, South Korea’s first mission to the Moon. Using a polarimeter instrument called PolCam, KPLO will collect extensive polarization images of the Moon to learn more about the nature of the lunar surface and for comparison with other remote-sensing datasets, such as reflectance spectroscopy, thermal emission and radar backscatter.