Roberto Furfaro, University of Arizona; Vishnu Reddy, University of Arizona; Tanner Campbell, University of Arizona; Bill Gray, University of Arizona
Keywords: XDA, Cislunar SSA,optical tracking, orbit determination
Abstract:
As humans plan to return to the Moons surface as early as 2024, many nations are already deploying an increasing number of space objects in the Cis-lunar space. Defined as the volume comprised within the Moons orbit, general awareness of cis-lunar space is critical to support unconstrained access and operations including both surface and orbital domains. However, legacy Space Domain Awareness (SDA) systems were not designed to detect, track and catalog space objects transiting in such environments. This has given rise to a new discipline named Cis-Lunar Space Domain Awareness (XDA). XDAs fundamental goal is to build and maintain a catalog of space objects transiting and residing in the cis-lunar space using a combination of ground-based and dedicated space-based platforms. XDA is extremely important for many reasons. Currently, most activities in cis-lunar space are going unmonitored and only self-reported. Continuous detection, tracking, and monitoring of such space objects is highly desired to 1) avoid strategic surprises; 2) maintain strategic and tactical high ground; 3) support US allies and partners; and 4) protect humans in space by ensuring safe access to the lunar surface. Effective XDA is nevertheless challenging. Indeed, comprehensive coverage from ground-based optical telescopes is limited by the moons brightness. This difficulty of imaging space objects within ~15 deg from the Moons center defines the so-called Cone of Shame. Conversely, active radar systems may require a prohibitive amount of power to illuminate space objects at lunar distances.
In this talk, we present the results of the University of Arizona-led campaign in observing and tracking of the Change 5 spacecraft and the booster en-route to the Moon. Part of the Chinese lunar exploration program, Change 5 is the 5th lunar exploration mission and Chinas first lunar sample return mission. The spacecraft was launched at 20:30 UTC on November 23, 2020 from the Wenchang Spacecraft Launch Site and landed on the lunar surface on December 1, 2020. The overall theoretical and practical goal of the observational campaign was to answer the following question: How long can one keep optical custody of the spacecraft and its booster on its way to the moon and back. The campaign employed a combination of publicly available RF data and augmented with optical observations collected with the a 0.5-meter, F/2.8 Raven-class telescope located in Tucson, Arizona. Data were processed using orbit determination methods and tools typically employed in tracking Near Earth Objects (e.g. iterative batch least square, simplex methods) to iteratively reconstruct trajectories for both spacecraft and boosters. As a result, we successfully demonstrated optical recovery and custody of the rocket booster. Additionally, optical astrometry was used to successfully predict the impact location and time of the cis-lunar return vehicle. Importantly, we demonstrated the feasibility of collecting optical measurements for spacecraft located well within the cone of shame using Raven-class telescopes.
Date of Conference: September 14-17, 2021
Track: Cislunar SSA