Guido Pedone, Airbus Defence and Space GmbH; Jens Utzmann, Airbus Defence and Space GmbH; Roger Förstner, Universität der Bundeswehr München
Keywords: Observation Scheduling, Admissible Regions, Virtual Debris
Abstract:
The rise of new satellite constellations, especially in the LEO region, together with an increasing number of new launches and wider participation in space-related activities from various entities is pushing Earth orbits toward maximum capacity. Together with the necessity of a worldwide set of regulations for the Space Traffic Management (STM), there is the need to provide a proper surveillance support for the cataloguing of the increasing number of uncooperative space objects, e.g. launchers bodies, dismissed satellites and fragmentation events.
Differently from radar facilities, in-space and on-ground optical observers can offer additional data (with respect to the canonical observables like coordinates, range and relative rates) and cover higher orbital regions with reduced energy consumptions. Optical sensors offer the possibility to deal with illuminance information of the objects, the albedo information and the change of measured magnitude with time. This information can be combined to perform initial object characterization (e.g. shape and attitude information). However, a certain number of constraints come together with optical sensors: mechanical-constrained slewing capabilities, narrow fields of views (FOVs), illumination constraints such as the objects need to be in direct sunlight and local darkness (night) in case of ground station observer.
When any particular observation strategy is adopted, unpredicted passages or new objects detections are generally constituted by short arcs, produced by objects crossing the FOV of an observer at high relative velocities. These short arcs are generally insufficient to trigger properly a weighted least squares reduction of the orbit. Since any initial orbit guess can be correctly established for short detections, the features that have possibly generated those detections need to be re-observed in order to be correlated with each other. Despite the wide literature available in the field of short arcs correlation, the sensor scheduling strategies that are necessary to re-observe the same object after a short crossing of the FOV are difficult to be realized by common telescopes and often involve a great number of world-distributed observers to create feasible object coverage. Currently, the biggest challenge for a network of observers is to not be overloaded by redundant tasks and to be optimized in their operations.
This paper will open with a state of the art review of the common data processing techniques and observation strategies for Catalogue Generation, followed by the description of a new method for the re-observation of short arcs. The state of the art will summarize the requirements coming from the correlation and initial orbit determination cataloguing tools necessary for the creation of a catalogue of space objects. The new method will consider post-processing strategies to keep track of new detections using Constrained Admissible Regions (CAR) to triangulate possible objects that may have generated the measurements. A proper triangulation of the CAR generated by a short arc, together with some refinement filtering techniques in case of more measurements, will allow the generation of a family of Virtual Debris (VD). Eventually, a proper covariance matrix can be associated to each family of VD and their future observability studied. The work and the simulation presented during this paper take place in the framework of the Airbus Defence and Space SSA department, where this research has been conducted. The software tool SPOOK (Special Perturbations Orbit determination and Orbit analysis toolKit) used during the simulation, together with the sensing facilities, such as the Airbus Robotic Telescope (ART) in Spain, used for real observation campaigns.
The observation strategy will be presented as completion of a wider cataloguing system that can be fed by different sources, i.e. Space-track online catalogue and SMARTnet participation. However, special attention will be given to the Catalogue Generation chain that is the first essential part of a cataloguing system.
Date of Conference: September 14-17, 2021
Track: Dynamic Tasking