Tae Lim, United States Naval Academy; Francis Chun, U.S. Air Force Academy; Benjamin Roth, U.S. Air Force Academy; David Strong, Strong EO Imaging, Inc.; Timothy Giblin, i2 Strategic Services LLC
Keywords: Rocket body rotational motion characterization, photometric observation, Falcon Telescope Network, space debris removal
Abstract:
Title: “Correlation of Rotational Motion of Rocket Bodies with Falcon Telescope Network Photometric Observations”
Tae W. Lim1, Francis K. Chun2, Benjamin D. Roth2, David M. Strong3, and Timothy W. Giblin4
1 Air Force Summer Faculty Fellowship Program Fellow, Aerospace Engineering Department, United States Naval Academy
2 Department of Physics and Meteorology, United States Air Force Academy
3 Strong EO Imaging, Inc. in collaboration with the United States Air Force Academy
4 i2 Strategic Services, LLC in collaboration with the United States Air Force Academy
Space object population, both operational and defunct, has been growing rapidly in recent years and poses an increasing risk for safe operation of space assets on earth orbits [1]. A heightened space situational awareness (SSA) is called for to mitigate the risk of collision and potential loss of space assets. Strategies and technologies for space debris mitigation and removal are in development to ensure safe operating environment. Of particular interest are the rocket bodies (R/Bs) left in orbit after launching satellites as they pose significant potential threats to space assets by increasing space debris as they lack maneuvering capabilities to avoid collision [2]. To remove them safely, debris removal technology requires knowledge of their rotational motion profiles such as tumble rates, spin stability, and attitude.
The Center for Space Situational Awareness Research (CSSAR) in the Department of Physics and Meteorology at the U.S. Air Force Academy has been conducting research in space object characterization using non-imaging photometric observation data. A network of small aperture telescopes located around the globe, called the Falcon Telescope Network (FTN) [3] was developed to conduct observation of various resident space objects (RSOs) in low earth orbits (LEOs) as well as geosynchronous earth orbits (GEOs) to perform their identification and characterization [4-6].
The objective of this research is to develop modeling and simulation capabilities for R/Bs in LEO to characterize and validate their rotational motion profiles using the correlation of the model predictions against the observed photometric data available from the FTN. This modeling process incorporates four major contributors to the photometric measurement data: rotational motion profiles, R/B geometry, optical properties, and R/B observation geometry. The photometric reflection data of R/Bs measured by FTN is provided as light curves, showing relative reflected light intensity over observation duration. Even for the same R/B, depending on the time of observation, solar phase angle, and FTN site location, the light curves exhibit varying behaviors such as monotonic decrease (or increase) or oscillation with varying frequencies. Identifying contributors to these light curve behaviors would help characterize rotational motion profiles of R/Bs and thus their removal operations as needed.
To investigate rotational motion, which is considered to be least known, R/B was treated as an axisymmetric cylindrical rigid body. Several R/Bs observed extensively by the FTN were selected as candidates. Using the published data [2, 7], their dimensions (length and diameter) and structural mass were obtained and employed to estimate their inertia values. Then the correlation of the inertia properties with rotational motion including spin, nutation, and precession behavior was examined. Behavior of a cylindrical body on orbit induced by environmental disturbance torques such as gravity gradient and aero drag was also examined including the effect of having initial tip-off rates. Initial investigation indicates that the length over diameter (L/D) ratio of R/B has a significant impact on nutation and precession behavior, thus resulting photometric light curves. For R/Bs with larger L/D ratio tend to have a longer oscillation period in the light curves. For the same object, oscillation frequency observed in the light curves can change by a factor of two solely by changing the orientation of sun vector with respect to its angular momentum vector. A similar behavior was observed in the measured light curves.
To perform systematic correlation studies between the simulated and measured light curves, parametric study model was developed including the four components mentioned above. To refine the correlation process, the observation conditions of available photometric measurement data will be employed to provide R/B observation geometry including solar phase angle and FTN location. Correlation between simulated and measured photometric data will help validate the rotational motion modeling process and thus provide means to characterize rotational motion profiles such as tumble rates, spin stability, and attitude, that are needed for safe removal of rocket bodies.
Distribution A. Approved for public release: distribution unlimited. (PA #USAFA-DF-2025-99)
Disclaimer:
“The views expressed in this article, book, or presentation are those of the author and do not necessarily reflect the official policy or position of the United States Air Force Academy, the Air Force, the Department of Defense, or the U.S. Government.”
References
Maclay, T. and Mcknight, D., “Space environment management: Framing the objective and setting priorities for controlling orbital debris risk,” Journal of Space Safety Engineering, 8(1), 93-97, 2021.
Stromberg, T., Wilson, K., Bate, T., Chun, F., Strong, D., McKnight, D., “Stability Analysis of LEO Rocket Bodies,” Proceedings of Advanced Maui Optical and Space Surveillance Technologies, 2023.
Francis K. Chun et al 2018 PASP 130 095003.
Masters, A.W., Wilson, K.W., Chun, F.K., Strong, D.M., Schuetz-Christy, C.P., “Analysis of Photometric Signatures of DTV-10 Collected 8 Years Apart” Proceedings of Advanced Maui Optical and Space Surveillance Technologies 29 Sept 2022.
Albrecht, E.M., Jensen, E. K., Wilson, K.A., Key, J.A., Harley, J.L., Chun, F.K., Ruby, N.H., K. Strong, D.M., Schuetz-Christ, C.P., “Calibration of the Falcon Telescope Network for Geosynchronous Satellite Photometric and Spectral Signatures” Proceedings Advanced Maui Optical and Space Surveillance Technologies 14 Sept 2021.
Tippets, R.D., Chun, F.K., Dearborn, M.E., and Gresham, K.C., “SL-8 Spin Axis Determination,” International Astronautical Congress, Naples, Italy, 1-5 October 2012.
Anselmo, L., and C. Pardini. “Ranking upper stages in low Earth orbit for active removal.” Acta Astronautica 122 (2016): 19-27.
Date of Conference: September 16-19, 2025
Track: Satellite Characterization