Adrienne Rudolph, ExoAnalytic Solutions; Phillip Cunio, ExoAnalytic Solutions; Marcus Bever, ExoAnalytic Solutions; Christopher Bolig, ExoAnalytic Solutions; Doug Hendrix, ExoAnalytic Solutions; Stuart Eves, SJE Space Ltd
Keywords: Space Plasma Environment, Plasma Physics, Space Propulsion, Propellant Plume Expansion, Optical Plume Characterization, Space Domain Awareness,
Abstract:
ExoAnalytic Solutions (Exo) have used their global space surveillance telescope network to track a range of ongoing activities in the vicinity of Geosynchronous Earth Orbit (GEO), collecting imagery and other observational metadata that illustrate and quantify satellite maneuvers, satellite anomalies, proximity operations, and orbit insertions. During large delta-V orbit insertions it has proven possible to observe propellant plumes emitted by the upper stages of several different rocket motor systems and observe the subsequent behavior of this material. The propellant plumes of a select group of spacecraft during their respective insertion maneuvers have been found to exhibit counterintuitive behaviors that appear to be influenced by the plasma environment at GEO. Specifically, the plumes appear to maintain a relatively static shape over longer time durations than a neutral gas dynamics model would predict.
This paper will address the plasma environment at GEO and its interaction with propellent plumes. The main technical focus of this effort is modeling and simulating the observed propellant plumes in a magnetized plasma using magnetohydrodynamic and particle-in-cell codes and estimating the degree to which the observed plumes fit each model. Inputs to the plume model will be taken from known propulsion system parameters and analysis of plume observations (i.e. video sequences and accompanying data). The plasma environment will be modeled as a magnetized plasma using a plasma environment with varying degrees of ionization and, given that the details of the satellite propulsion systems are reasonably well known, it may be possible to estimate properties of the space plasma environment.
Data on known propulsion systems and the measured plasma environment will be compared with the relevant parameters estimated from the video sequences in order to evaluate the accuracy of the calculations made. The video sequences are comprised of black and white, frame-by-frame, captures of inserting spacecraft observed by Exo’s optical telescopes, where relevant parameters consist of the size, shape, density, mass, and velocity of the plumes with respect to the telescope’s Field of View (FoV) and the spacecraft. Understanding propulsion system data necessitates the identification of the type of second-stage engines used, as their primary mission focuses on orbital maneuvers and insertions of payloads. Depending on the mission of the spacecraft, the specifications of their engine, fuel and oxidizer, fuel tanks, specific impulse, thrust, and fuel mixture ratio can provide information on the spacecraft’s maneuver capabilities as well as the mass, density, and velocity of the expelled propellant plumes. Methods of analysis include creating an algorithm to process image data and measure the relative velocity and size of the moving plumes with respect to the spacecraft. Furthermore, the strength of the dielectric field can be estimated from the visible length of the glowing propellant stream. The simulated plasma environment can also illustrate how the thermal energy of different propellants should differ under various levels of ionization.
This work may yield results indicating how a specific propellant, or combination of propellants, can interact with the plasma environment at GEO to produce the visual results of long-lived, shape-sustaining propellant plumes from inserting spacecraft. Knowledge of the effects of the plasma environment on spacecraft propellant plumes can prove instructive in the effort to characterize objects at GEO for which we have incomplete information. Furthermore, by anchoring the results of our simulations with observations, it may be possible to determine what effects are likely to occur for various types of expended propellant in the charged environment at GEO, as well as eventually aid in the identification of the fuels and oxidizers used by spacecraft for which the propellant types are unknown. Lastly, a thorough understanding of the plasma environment at GEO and how it interacts with expended propellants may lead to future work in investigating how the geomagnetic activity of the plasma can affect spacecraft, their instruments, and other onboard systems.
Date of Conference: September 19-22, 2023
Track: Atmospherics/Space Weather