Survival Analysis for Nanosatellites and Picosatellites

The nascent field of fractionated satellite architectures provides an opportunity to improve spacecraft modularity and afford greater flexibility, adaptability, and upgradeability to spacecraft constellations. Satellite modules within a coherent formation can be replaced without facing the challenges of manufacturing, assembly, or disassembly in the harsh space environment (e.g., satellite modules conducting electromagnetic formation flight (EMFF) are not physically connected such that one module may be replaced with potentially less risk of damaging or degrading the performance of the other modules). Conventionally, the depot for constellation replenishment is located on Earth, however, minor augmentations to spacecraft formations cannot be conducted economically under such a framework. The present research proposes the utilization of proactively launched supply depots to replenish geostationary formations from ultrageostationary orbit (i.e., that volume of space encompassed between the altitude of geostationary orbit and the altitude of the L1 Lagrange point). This work explores reliability factors associated with such a concept by conducting a survival analysis for nanosatellites and picosatellites. Time to failure data is collected for 85 spacecraft in the nano- (1.01 – 10 kg wet mass) and pico- (0.11 – 1 kg wet mass) classes without data censoring. These spacecraft were launched between 2010 and 2019, inclusive, having an internationally diverse set of owners from the sectors of military, government, commercial, and academia. This data is used to build a distribution for the survival analysis of satellites in these classes. JMP Pro 13 is used to conduct a goodness-of-fit test for multiple distributions. Analysis (using a standard alpha value of 0.05) indicates that the data is from a two-parameter Weibull distribution wherein the spacecraft experience beneficial aging