The Emission of Nonthermal Electromagnetic Radiation by Colliding Space Debris

Abstract Introduction The Intelligence Advanced Research Projects Activity’s (IARPA) Space Debris Identification and Tracking (SINTRA) program seeks to understand the interaction of orbital space debris with the surrounding space environment to determine if this interaction can be used for detecting, characterizing, and tracking potentially lethal, currently non-trackable orbital space debris [1]. Here, we show that non-thermal electromagnetic (NTEM) radiation generated by space debris colliding with each other at hypervelocity, defined as a relative speed larger than the speed of sound in the debris, can be used to detect and characterize currently non-trackable orbital space debris. Using state-of-the-art numerical simulations and theory, we demonstrate that collisions of mm-sized orbital debris at hypervelocity emit NTEM signals strong enough to allow ground-based detection of collisions even at geosynchronous orbit (GEO). We postulate that these signals allow the estimation of debris mass, relative velocity, size, and possibly composition. In addition, we demonstrate a novel methodology to distinguish between radio frequency (RF) signals from NTEM, thermal radiation, and radio frequency interference (RFI) [2]. While the concept of utilizing NTEM radiation to detect debris remotely has not been previously explored, the generation of intense electromagnetic pulses (EMPs) by hypervelocity impacts is well established, because they pose risks to spacecraft electronics [3–6]. Modeling and experimental results indicate that EMPs produce RF signals ranging from a few MHz to GHz [4, 6–8]. Hypervelocity impacts and the corresponding EMPs have been detected in-situ by various spacecraft, most recently by the Parker Solar Probe [9].