The photometric detection of known sun occluding orbital debris.

摘要

In this research, discrete, digital, Sun transit images are used for the photometric detection of the shadows of Sun occluding satellites. A theoretical pixel occlusion ratio is developed for use in the detection and the occluding area determination of satellites and orbital debris, traveling over known, or predicted, spatial temporal paths during transit. To verify the occluding area determination of a large satellite, a recorded transit of the International Space Station is analyzed. Also an experimental system, funded by a Beverly Sears Grant and a Sigma-Xi Grant-In-Aid of Research, consisting of a Meade ETX-90 telescope, and a Lumenera LU-075 camera is constructed to detect satellites and orbital debris in solar transits. The photometrically measured total occluding area of the Terra EOS-AM1 satellite, recorded in two separate transits, is shown to be consistent with the predicted occluding area of the satellite shadow.;Further investigated is the theoretical resolution limit of this detection, as the occluding shadow becomes much smaller than a pixel area. The central limit theorem is used to approximate the maximum detection statistic, which can be achieved when integrating a matched spatial temporal path, containing the moving shadow. This detection statistic is predicted to be a function of the pixel occlusion ratio, the design parameters of the spatial temporal path, and the approximated Poisson variance of the photon count in each pixel. When the measured detection statistics of the two recorded transits are compared with the prediction model, the measurements agree with half the predicted value. This experimental error is largely attributed to filter mismatch in the spatial temporal path, and a spatial temporal variance in the recorded Sun transit images, which is larger than predicted by theory.;These experimental verifications of the proposed theory are used to extrapolate the general limitations and capabilities of a system designed to detect Sun occluding orbital debris. In particular, the potential resolution capability of a system designed to detect smaller orbital debris is theorized.