Feasibility Study of Space-Based Techniques for Measuring Millimeter-Scale Orbital Debris Flux

Abstract

The increasing density of space debris poses a growing threat to satellite operations and future missions. While sub-millimeter debris is studied through impact craters and objects larger than 0.5 cm are tracked by ground-based radar, debris in the 1–3.2 mm range remains largely unmonitored. This thesis investigates the feasibility of using space-based techniques to estimate the flux of millimeter-scale debris, focusing on two approaches: (1) active detection using a CubeSat-mounted millimeter-wavelength radar, and (2) passive detection using collision statistics derived from Starlink satellite ephemeris data.

A radar simulation framework was developed to evaluate system performance across key parameters, including antenna size, frequency, transmit power, and noise bandwidth. The NASA ORDEM model was used to estimate debris flux and validate detection capabilities. The optimal radar configuration, operating at 100 GHz with a 15 cm antenna, 10 W transmit power, and 50 kHz noise bandwidth, was found to detect over 14,000 debris objects per year in a 900 km polar orbit, with an estimated uncertainty of $\pm28\%$.

In contrast, the passive method identified only one high-confidence anomaly from 500 Starlink ephemeris files, likely due to limited data resolution and conservative detection thresholds. While radar offers a more direct and scalable solution for mm-scale debris detection, collision statistics may serve as a complementary method, particularly as onboard sensors and data-sharing practices improve.

These findings support the feasibility of CubeSat radar missions such as UNICube and QBDebris and provide concrete design recommendations to help close the observational gap for millimeter-scale debris.