Bernie Klem (United States Air Force, Arnold Engineering Development Center, Advanced Missile Signature Center), Dave Swann (United States Air Force, Arnold Engineering Development Center, Advanced Missile Signature Center)
Keywords:
Abstract:
Recent advances in spacecraft health monitoring have resulted in successful applications of photometry and light curve analysis to quantify measurable changes to the spacecraft by passive means. Subtle changes in degradation of spacecraft material properties, reorientation of central body attitude, and slight misalignment of major signature producing components (extended solar panels) are often detected under non optimized viewing conditions. It is beneficial to the observer / analyst to understand the fundamental optical signature variability associated with these detection and identification processes.
This presentation captures the fundamental observable variations of representative convex surfaces that may exist in the surround for which the subtle change processes need to be detected. The key surface parameters include shape, orientation, altitude, surface – sensor – light source scenario, and material reflection characteristics. Specifically, the talk summarizes radiant intensity patterns as a function of prioritized key parameters as generated from moderate – to – high fidelity simulations. The intent is to provide the analyst with an information – base capability to select the observation – sensing scenario that has an increased likelihood of successfully monitoring changes to the spacecraft.
The focus of the paper is to present a graphical database summary of typical meter – size convex surfaces that include a right circular cylinder, a right circular conical frustum, a right circular cone, and a thin circular disk. These objects are modeled in their major in – plane and out – of – plane orientations with respect to the sun and the earth, while situated at a low earth orbit (LEO) and a geostationary earth orbit (GEO) altitude location. Results are presented for broad visible spectral band observations as the sensor performs a complete “walk – around” of the objects in the solar and solar – perpendicular planes to capture the diffuse and specular reflection signature characteristics resulting from both the direct sun and the earth albedo. Results are also presented for the cases where the space objects experience complete tumbling motion in these planes while being observed from a fixed sensor location. A partial database has already been generated demonstrating the complexity of the earth albedo diffuse and specular glint patterns for LEO altitude surfaces.
Continuous engagement with conference participants in the poster session is anticipated to provide a discussion agenda for expansion of the presented topics to include such areas as: (1) simultaneous multiple color sensing, (2) introducing hi fidelity spectral material property simulation capability to the database, and (3) developing infrared observable features into the sensing and status identification algorithms.
Date of Conference: September 1-4. 2009
Track: