James C. Jones, Northrop Grumman; Michael Strong, Northrop Grumman
Keywords: orbital debris, remediation, modeling, ORDEM, debris, LEO, Low Earth Orbit
Abstract:
NASAs Orbital Debris Program Office estimates the population of small debris (particles between 1 and 10 cm) at approximately 500,000. The number of particles smaller than 1 cm exceeds 100 million. Although small, these objects can cause significant damage to operational satellites due to the orbital velocities and large transfer of kinetic energy in collisions. To protect our operational spacecraft, the best course of action is to prevent the unnecessary creation of debris. This has been the focus of the U.S. National Space Policy efforts and generally tends to focus on preventing large objects from colliding or exploding thus becoming small debris. It appears inevitable, given the proliferation of satellite constellations due to the lowered bar to entry into the space environment, that collisions will occur and significantly increase the number of small debris. This paper focuses on the modeling of various debris collection schemes using a predator-prey model with debris collection satellites as predators and debris as prey. This modeling effort explores a hypothetical aftermath of catastrophic collision events and a rapid increase to double the current debris population. The model computes the duration of debris abatement efforts for a variety of collection satellite schemes. Assumptions about the collection satellites include: the material technology for hypervelocity collision is sufficient for survival, collisions are with small debris only, the orbital trajectory of the collection satellite is maintained after a collision, all collisions result in the capture of the debris, and no extra debris is generated in the process. While these assumptions pose significant engineering problems, they are necessary conditions to explore the effectiveness of such an approach to debris abatement and determining measures of success. These engineering challenges may be overcome through dedicated investment in collision energy control technology for satellite systems. Collision rates for various orbital parameters are determined using the NASA Orbital Debris Engineering Model. Specifically, orbital inclination and altitude, which determines collision velocities, transferred kinetic energy, and survivability. The modeling effort also explores consolidation and disaggregation methodologies on mitigation. Initial modeling of a hypothetical collision that doubles the debris population, followed by deploying a predator platform with a 900 square meter collector at a 98-degree inclination angle at 950 km altitude, and using a rate of 4 collisions per square meter per year, would slow debris growth significantly but would be insufficient to return the population back to its original state. The model results indicate a total of 10 collectors would return the population back to original levels but would take decades. Also included is a discussion of the various assumptions in the model. The results show the importance of preventing disastrous collisions and unfortunately lay out the inevitability of the cost of rapid satellite proliferation.
Date of Conference: September 27-20, 2022
Track: Space Debris