Nanosatellite Cluster Launch Collision Analysis

Nanospacecraft are usually launched in clusters from a single launch, in which they are hosted as secondary payloads. The nanospacecraft, e.g., CubeSats, are usually released simultaneously in small groups from one single container, to simplify the launcher interface manufacturing and the launch operations. The release sequence must be designed to minimize the risk of collisions among the nanospacecraft themselves. Considering the increasing number of micro- and nanosatellites in recent space activity, a collision risk analysis and a release systems configuration optimization are of interest. This paper describes a collision probability analysis for a nanosatellite cluster deployment, performed by a series of Monte Carlo simulations, comparing results obtained with different release mechanisms, procedures, and orbital dynamics modeling assumptions. The collision risk in the first orbits after launch depends mostly on the in-orbit injection initial conditions, such as relative initial position and velocity, which directly reflect on the satellite dispenser configuration, interface concept, and mechanical parameters. The model used for the analysis is based on the Encke equations for the relative motion, considering the main perturbations acting on the satellites, such as Earth gravitational field higher harmonics, Moon and Sun third-body perturbations, solar radiation pressure, and atmospheric drag. The risk of collisions is assessed performing Monte Carlo simulations based on the numerical integration of the equations of motion. The final results provide the collision probability assessment and the influence that the release device configurations have on this risk.