| Partial Stokes imagery using a four channel simultaneous polarimeter was collected on May 15, 2004 of the International Space Station (ISS) during a pass over Colorado Springs, Colorado. This is the first time simultaneous Stokes imaging polarimetry has been collected on an artificial satellite in earth orbit. Imagery was collected using a 317.5 mm TORUS Cassegrain telescope in an F10 configuration. A Takahashi NJP 160 mount modified with high torque motors in a direct drive configuration was used as the tracking mount.; This polarimetric imagery demonstrated that small aperture telescopes matched to the Fried parameter and coupled with a camera framing at 30 fps collect good quality polarimetric satellite imagery. The frequency of the good images corresponds to a Fried parameter of 60 mm.; The DOLP values on the spacecraft are in the range of 20--45%, more than a factor of five above the NeDOLP uncertainty providing confidence that the DOLP values are derived from actual polarization present in the reflected intensities. In the case of the ISS significant polarization is present and persists through a column of air 386--480 km in depth. If these results can be extended to other spacecraft then polarimetry may provide an additional modality for exploitation. |
