The NASA Orbital Debris Program Office has acquired telescopic lightcurve data on massive intact objects, specifically spent rocket bodies (R/Bs), to ascertain tumble rates in support of the Active Debris Removal (ADR) studies to help remediate the LEO environment. Tumble rates are needed to plan and develop proximity and docking operations for potential future ADR operations. To better characterize and model optical data acquired from ground-based telescopes, the Optical Measurements Center (OMC) at NASA/JSC emulates illumination conditions in space using equipment and techniques that parallel telescopic observations and source-target-sensor orientations. The OMC employs a 75-W Xenon arc lamp as a solar simulator, an SBIG CCD camera with standard Johnson/Bessel filters, and a robotic arm to simulate an object’s position and rotation. The OMC does not attempt to replicate the rotation rates, but focuses on ascertaining how an object is rotating as seen from multiple phase angles. The two targets studied are scaled (1:48) SL-8 Cosmos 3M second stages. The first target is painted in the standard Russian government “gray” scheme and the second target is white/orange as used for commercial missions. This paper summarizes results of the two scaled rocket bodies, each observed in three independent rotation states: (a) spin-stabilized rotation (about the long axis), (b) end-over-end rotation, and (c) a 10° wobble about the center of mass. The first two cases represent simple spin about either primary axis. The third – what we call “wobble” – represents maximum principal axis rotation, with an inertia tensor that is offset from the symmetry axes. By comparing the resultant phase and orientation-dependent laboratory signatures with actual lightcurves derived from telescopic observations of orbiting R/Bs, we intend to assess the intrinsic R/B rotation states. In the simplest case, simulated R/B behavior coincides with principal axis spin states, while more complex R/B motions can be constructed by combinations of OMC-derived optical signature that together form a rudimentary basis set. The signatures will be presented for specific phase angles for each rocket body and shown in conjunction with acquired optical data from multiple telescope sources. The results of the data show possible correlations between the laboratory data and telescopic data for the rotations states mentioned above (b) and (c), but with limited data the results were not definitive to differentiate between color schemes and rotations. The only rotation that did not correlate with the observed telescopic data was the spinstabilized rotation. 1.0 Introduction Capitalizing on optical data products to generate a more complete understanding of orbital space objects is a key objective of NASA Orbital Debris Program Office’s optical measurements program and a primary objective for the Optical Measurements Center (OMC). The OMC is used to emulate space-based illumination conditions using equipment and techniques that parallel telescopic observations and source-target-sensor orientations. Timedependent optical photometric data yield lightcurves in multiple bandpasses. This aids in material identification and assessment of possible periodic orientations of orbital debris. These data can also be used to help identify shapes and optical properties at multiple solar phase angles (SPA). This paper focuses on 1:48 scale SL-8 rocket bodies to extract lightcurves for the following rotations: (a) end-overend, (b) 10° wobble, and (c) spin-stabilized. These three states were chosen based upon the most likely rotational axes of rocket bodies (a and b) [1] and the simplest rotational state of a cylindrical rocket body (c). The output will be used to develop a database of optical signatures for comparison with and interpretation of telescopic data. https://ntrs.nasa.gov/search.jsp?R=20120007406 2019-11-10T10:21:34+00:00Z