Marielle Pellegrino, University of Colorado Boulder, The Charles Stark Draper Laboratory Inc.; Daniel Scheeres, University of Colorado Boulder, The Charles Stark Draper Laboratory Inc.; Brett Streetman, University of Colorado Boulder, The Charles Stark Draper Laboratory Inc.
Keywords: space debris, astrodynamics, chaos, gnss, meo
Abstract:
Characterizing the long-term dynamics of debris events is crucial to sustainability of the space domain. Collisions and breakups that create debris clouds possibly beget more collisions in the future. This domino effect of debris creating more debris is known as the Kessler Syndrome. To help prevent the tipping point of rendering orbits no longer usable due to traffic of space debris, running long-term simulations of the orbital environment is important. This will inform the dynamics of the environment and the best approaches to maintaining it. In geosynchronous orbit, we have already seen that orbital debris can behave much differently than satellites. The high area-to-mass ratio (HAMR) objects, suspected to be pieces of mylar, oscillate about the Laplace plane instead of remaining in the preordained graveyard orbit of the region. This behavior helps motivate the need to examine the behavior of debris created by varying events in other orbital regimes before determining the ideal practices for sustaining the regime.
This paper will focus on studying debris clouds in medium Earth orbit (MEO). MEO is utilized by Global Navigation Satellite Systems (GNSS) which are critical to the global economy or our modern world’s way of functioning. A unique aspect of MEO is that it is subject to destabilizing resonances due to the Sun and Moon. These perturbations influence the orbit by causing chaos in the dynamics. The orbits can rapidly increase in eccentricity under these resonances and thus objects in the region can interact with nearby orbits or even reenter the Earth’s atmosphere in as short time as a couple of decades. Studying the long-term stability of the GNSS nominal orbits and their surrounding regions is critical to informing the sustainable practices of satellite disposal in the region.
In particular, we will examine the behavior of the objects in the region created by two types of events. The first event is a debris cloud modeled after a breakup event; this is similar to if some type of explosion occurred on the satellite after it was disposed. The other event is a debris cloud modeled after the collision between two satellites of the region. We will explore the three main satellite systems currently in orbit in the region Galileo, GLONASS, and GPS. All of these debris clouds are generated by the NASA Orbital Debris Program Office.
Our research will involve propagating these debris clouds with averaging techniques used to study the region in previous work. We will not only look at the exact initial conditions for the event but also extrapolate those results to nearby regions. This will involve using a statistical analysis to scale some of the results for varying semi-major axes in addition to more simplistic fluctuations such as varying the longitude of the ascending node and initial epoch. By studying the events under these varying conditions, we will be able to see how debris clouds interact with the known resonance structure of the region. We don’t nescessarily expect to see the debris cloud exactly match the structure of the resonances since with an event a large amount of energy has been added to the system. However, in preliminary results, we find that some of the known areas to be subject to chaotic behavior result in eccentricity increases in the debris cloud.
This analysis will also be important to understanding how varying area-to-mass ratio objects behave with the conjunction of solar radiation pressure and luni-solar resonances. There has already been work in studying a few cases of HAMR objects in the region but not as large a study as surveying what an actual breakup or collision event provides. This study will help ensure that we are making safe decisions for sustaining MEO based on not only the types of objects currently in orbit but also the types of objects that can be created after long-term use of the orbit.
Date of Conference: September 14-17, 2021
Track: Conjunction/RPO