3-stage Pre-custody Filter (3PF)

A major challenge for Space Situational Awareness (SSA) -- a subset of Space Domain Awareness (SDA) -- and counterspace operations (CsOps) is that the number of Resident Space Objects (RSO) – satellites as well as debris – is increasing exponentially while their physical size is decreasing.  This makes all four functional capabilities for SSA more challenging, in particular the Data Fusion (DF) functions of detecting, tracking, classifying, and characterizing Space Potential Threat Events (SPTE) fast enough and with enough certainty to allow effective and timely CsOps.  For many reasons, achieving custody of new object – meaning determining its orbital parameters – can take more time than is allowable for effective CsOps when SPTE are unexpected and imminent.  We have researched and prototyped an innovative alternative approach that can provide Quick Reaction (QR) Indications and Warning (I&W) of SPTE we call “3-stage Pre-custody Filter” (3PF). This is an Upstream Data Fusion (DFU) approach based on comparing EOIR space sensor observational data with synthetically-generated imagery to detect unexpected observations that may be indicative of SPTE.  The first stage of the filter is to compute the differences – called residuals -- between predicted synthetic and real image frames.  The second stage links or associates the residuals across frames to screen out spurious residuals.  The final stage then screens SPTE hypotheses based on their classification, threat evaluation, and a decision processes to determine if an SPTE alert should be generated.  If an SPTE alert is decided, an imagery snippet is made that is efficiently short but provides sufficient evidence along with the SPTE annotations for an operator to decide if CsOps mitigations should be taken, e.g., maneuver, Electronic Warfare (EW), or interception.  Four things make all of these operations feasible: Leveraging of existing technologies:  synthetic imagery generation, image change detection, Fast Linear Assignment Program, and Information Based Sensor/source A catalog of all RSO in custody, where custody in this domain meaning the object's orbital parameters have been determined.  Existing and well-established Simplified General Perturbations (SGP4) software is used to estimate the expected RSO image position in the focal plane. A Space Sensor Network (SSN) space sensor data that functions as a cloud in that all space sensor data is accessible via an API.  An example of an element of the SSN on the unclassified side is Unified Data Library (UDL). Most importantly, operators have stated that SPTE are “easily identified visually in calibrated imagery.” This DFU doesn’t replace but precedes and enhances the conventional Downstream Data Fusion (DFD) of filtering, correlating, classifying, achieving custody.  Rather, DFU augments DFD so that the “fusion” of DFU and DFD operations provides diversification that contributes to a more resilient architecture supporting mission assurance.