The Photopolarimeter/Radiometer (PPR) is designed to measure the
degree of linear polarization and intensity of reflected or
scattered sunlight and the intensity of thermally emitted
radiation from Jupiter and its major satellites.
Citation
Travis, L.D., T.Z. Martin, G.S. Orton, J.R. Spencer, L.K.
Tamppari, R.F. Beebe and L.F. Huber, GO-J-PPR-3-RDR-V1.0, NASA
Planetary Data System, 2002.