| Assessments of the orbital debris population rely on a variety of sources to generate a size distribution function. Among them are radar cross-section, statistical size distributions (e.g. from satellite break-up models), and optical cross-section from brightness with an assumed albedo and phase function (typically Lambertian sphere). Due to inverse square losses on transmission and reflection, radars are only effective for Low Earth Orbit (LEO) debris detection, while optical telescopes work well at all ranges and are the only practical sensor for geosynchronous orbit regimes (GEO). Current methodology for size estimates is limited by the remote sensing observables and cannot readily account for real-world object materials, surface topologies, orientations, or time-dependent behaviors. Thus, in an attempt to more accurately characterize the orbital debris environment, especially in the undersampled GEO regime, a laboratory was designed to mimic optical telescope measurements. A collection of targets was selected as a subset representing orbital debris and categorized based on their shape, size, and material type. In order to best simulate the orbital debris population, three main sources were used: flight-ready materials, destructive hypervelocity testing and destructive pressure testing. Laboratory optical characteristics of fragments were measured, including shape, phase angle dependence, and photometric and spectroscopic color indices. These characteristics were then compared with similar optical measurements acquired from telescopic observations in order to correlate remote and laboratory properties with the intent of ascertaining the intrinsic properties of the observed orbital debris. The results of this effort have expanded remote sensing data acquisition to include measurements deemed by the laboratory analysis herein to be directly applicable to providing a more comprehensive assessment of debris properties. Future work to extend the current experimental data will be discussed. |
