Thomas Joyce, University of Arizona; Ryland Phipps, University of Arizona; Craig Jacobson, University of Arizona; Tanner Campbell, University of Arizona; Adam Battle, University of Arizona; Daniel Estévez, Independent Researcher; Roberto Furfaro, University of Arizona; Vishnu Reddy, University of Arizona
Keywords: Cislunar Space, Tracking, Detection, Passive RF, Radio Frequencies, KPLO, Artemis-1, SSA
Abstract:
Radio waves and electromagnetic emissions can be observed using Earth-based sensor systems. By collecting the signal output from resident space objects (RSOs) a detection can be obtained and documented. Through the continuous observation of these radio frequencies a unique way of tracking can be established. This process is known as Passive Radio Frequency Observations, or Passive RF. It is a method that harnesses the power of low-attenuating space to Earth radio communications to passively track satellites communicating with the Earth without the use of active transmission signals, like those utilized in radar applications.
This ground-breaking method has a variety of competitive advantages that expands the opportunities of ground-based observations. With this technique accurate angular position and velocity estimation information can be obtained with a higher signal to noise ratio (SNR). Additionally, this method has the flexibility to be done regardless of time of day as well as during non-optimal atmospheric conditions. This can enable the possibility for 24-hour coverage of a specified target. The detection of these signals can also decrease ambiguity in object determination, as each target emits at a specified frequency with a known signal strength. Furthermore, this method is cost effective and can be a great addition into observation sites.
This technique of Passive RF was applied and tested using a prototype 0.6-meter S-band system. The objective of this study was to determine the efficacy of this method in relation to observable detection and orbit determination for RSO and cislunar objects. In the development of this program a methodology was devised and implemented to create a functional process for determining signal strength and the reconstruction of the orbits for objects operating in our local domain.
We present an academic implementation of this method, as the University of Arizonas Space 4 Center now operates the first Passive RF tracking station in the academic community. With the use of strategic space communication bands notable detections of 5 cislunar targets; Artemis-1, Lunar Reconnaissance Orbiter (LRO), Korean Pathfinder Lunar Orbiter (KPLO), Chandrayaan-2, and Queqiao were acquired.
The investment of this passive RF technique is sure to become a necessity in the future as human ambition and technological advancements continue to rise. The space domain is continuously under threat and the advantages this system provides can be combined with optical observations to create a network capable of withstanding variable and ever-evolving observing conditions.
We will discuss in detail the foundation of our tracking station, observational methodologies, achievable astrometric accuracy, and results of orbit determination for some of these objects.
Date of Conference: September 19-22, 2023
Track: Cislunar SDA