Site testing for space situational awareness

A single-detector stereo-SCIDAR system is being developed by the Research School of Astronomy and Astrophysics (RSAA) in conjunction with the Space Environment Research Centre (SERC) to characterise atmospheric turbulence above the Australian National University's Mount Stromlo observatory just outside Canberra. The EOS Space System's telescope at the Mount Stromlo observatory is to be used in future to track space debris to improve space situational awareness (SSA). Adaptive optics (AO) systems will be used to improve the resolution of the 1.8m debris ranging telescope located at the site. The SCIDAR system will measure valuable data including refractive index structure constant, C2n, and wind speed profiles. Also of interest are values of the Fried parameter, r0, and the turbulence temporal coherence time, 0, which will be used to optimise the AO systems' deformable mirror actuator pitch and correction rate. This system will be used in two modes: generalised SCIDAR and generalized stereo-SCIDAR. The generalised SCIDAR mode will overlap the pupil images of double stars on the detector whilst the generalised stereo-SCIDAR mode will separate the pupil images. Post-processed short exposures of the scintillation patterns of these double stars will extract altitude information of atmospheric turbulent layers. A stereo-SCIDAR system designed by another organisation separated pupil images onto a pair of separate detectors. However, our optical design utilises a compound roof prism to separate the pupil images and record them on a single detector. We discuss the optical and mechanical design of a stereo-SCIDAR system to measure the scintillation patterns of double stars separated by 10 to 25 arcseconds up to an altitude of approximately 15 km.