Kristen Tetreault, Virginia Tech; Shane Ross, Virginia Tech; Kevin Schroeder, Virginia Tech; Jonathan Black, Virginia Tech
Keywords: space surveillance, orbital debris, fragmentation, backward propagation
Abstract:
Sustaining the near Earth environment for future space vehicles and satellites requires an increase in the space communitys knowledge and understanding of the past, current, and future debris population. The leading source of space debris stems from fragmentation, or break up events. These events have become a particularly increasing concern, and are mainly due to either explosions or collisions. Some of these events result in just a few objects that could be short-lived orbiters before entering a terminal orbit. Others, however, create on-orbit fragments that contribute to the collision risk for satellites and space vehicles operating for a normal lifespan. Continuing to populate the near Earth environment with space debris without understanding the debris population could result in an even more overcrowded space environment encompassing satellite communications problems, navigation problems, and of course, enormous collision risk.
This paper presents a tool with the capability of identifying fragmentation events from existing space surveillance networks. This fragmentation identification tool determines the type of fragmentation event and the objects involved in the fragmentation event. Discussion will include a description of the algorithms implemented, a brief description of the tool, and a brief summary of its main functionalities. Short- and long-term evolution of the fragmentation clouds are studied, as well as the feasibility of determining the location and time of the fragmentation event. The tool calculates the time and location of the event, and identifies the true, pre-fragmentation objects involved in the event (commonly referred to as the parent objects). Additionally, study cases are presented including a parametric analysis by means of introducing variations in the input parameters of the tools model.
The method used to identify the fragmentation event involves back propagating the objects within the fragmentation cloud and computing at each time step the particle distribution of fragments, as well as this distributions variance. It is hypothesized that the fragmentation event has occurred when the particle distribution variance is at a minimum value. Once the event is identified, the location and time of the fragments initial orbit is computed. The parent objects involved in the event are identified by comparing this computed orbit with a satellite catalogue that contains the space population prior to the fragmentation event. For a precise determination of the event, the model uses a special perturbations numerical propagator for the backward propagation.
Back propagation techniques have previously provided limited accuracy stemming from errors in the calculation of drag perturbations due to limited knowledge of mass and area. This analysis introduces variations on the ballistic coefficient of each particle in the cloud based on that particles TLE history stemming directly from the satellite catalog. By manipulating the ballistic coefficient and weighting the particle’s area based on the radar cross section from the satellite catalog, the accuracy of back propagation can be increased, consequently increasing the accuracy of the fragmentation event identification.
Date of Conference: September 11-14, 2018
Track: Poster