Matthew C. Britton, The Aerospace Corporation; Joseph Mazur, The Aerospace Corporation; Timothy P. Graves, The Aerospace Corporation; George Vazquez, The Aerospace Corporation; Scott Daw, The Aerospace Corporation
Keywords: space control, space domain awareness, space traffic management, autonomous telescope systems, big data, data fusion, modeling, optical systems, imaging, spectroscopy, instrumentation, sensors, high performance computing
Abstract:
Geographically distributed ground electro-optical telescope networks that scale to large node count offer unique opportunities for space control, space domain awareness and space traffic management. Exponential growth in the number of resident space objects (RSO’s) from commercial mega-constellations and the emerging role of space as a warfighting domain stress capacity and timeliness of the existing Space Situational Network. This stressing condition arises from a scaling law mismatch between the exponentially growing number of RSOs and the linearly increasing number of sensors. A fully autonomous, distributed electro-optical sensor network that scales to hundreds to thousands of nodes can address the scaling law mismatch.
To scale successfully, a distributed ground sensor network must address both digital and material aspects in an autonomous way. The digital aspect of this problem encompasses ingest of RSO target lists, allocation of observations to sensor nodes, and retrieval/analysis/transport of sensor observations to network data centers for distribution to those who requested the observations. Scalability of this digital solution may be addressed through modern devSecOps, cloud computing and cloud storage methodologies. A scalable solution to the material aspect of this problem calls for autonomous, low size, weight, and power (SWaP) ground stations that require minimal maintenance and afford ample opportunities to field these stations at diverse geographical insertion points. This presentation describes scalable solutions to both the digital and material aspects of this problem that have been implemented as proof-of-concept by the Aerospace Corporation.
Aerospace’s scalable digital implementation is called Prime Focus. This implementation currently operates on a 24-hour cycle in which users upload RSO target lists via webform to launch an autonomous series of operations. These operations start by drawing catalog information from SpaceTrack and performing radiometric light curve modeling using Aerospace’s link budget simulator TRADIX. Scheduling algorithms employ these light curves to allocate time based on high signal-to-noise ratio opportunities. One scheduling algorithm uses the unclassified OI 534-09 category specification, in which observations are allocated based on a user-specified suffix rule. Other scheduling algorithms have been developed for specific applications. The schedule is regenerated upon each user-upload event, aggregating all target lists submitted over the past 24 hours to produce an updated schedule that is finalized at noon each day. This schedule is then written to Aerospace cloud storage and observation requests are transmitted via message bus to a 1m telescope at the Aerospace General Offices in El Segundo. This telescope acts as a surrogate for the scalable material solution described below. This 1m telescope executes each observing request and writes resulting observational data to cloud storage. The next morning a process traverses these data, issuing user-notification emails. This process will soon begin posting observational data to the Unified Data Library, encoding imaging and spectroscopic data in EOSSA format and using the Event Evolution schema to collate data aquired from different instruments within the same collect. Aerospace’s digital pipeline is implemented in a cloud-native context, relying on Jenkins for CI/CD, Docker for containerization, Kubernetes for deployment, and AWS S3 for cloud storage. Currently four entirely independent pipelines are operating on a continuous basis for evaluation, any one of which may be utilized by the 1m telescope to obtain observing requests and report observations. This demonstrates scalability of the digital implementation to multiple sensors, each of which is allocated an independent pipeline.
Aerospace’s scalable material implementation is called Monocle. This implementation employs a unique gimbal design developed specifically for autonomous telescopy. This design incorporates a two-axis Calotte dome and unifies the telescope pointing and tracking system and the dome steering system to minimize assemblies and SWaP. This allows the telescope optical tube assembly (OTA) and instrumentation to reside within the dome itself, with no opening to the external environment. There are substantial advantages to fully enclosing the OTA and instrumentation within an environmentally sealed, low-SWaP enclosure. The enclosed OTA and instrumentation are protected from contaminants, weather, and wind buffeting and may be baffled for stray light control. The interior of the enclosure may be thermally controlled, and there is no chimney effect that arises from hot air rising out of a dome opening. Aerospace has built a proof-of-concept prototype with a 125mm aperture OTA in a 450mm diameter dome. This prototype is constructed from COTS parts that are already commercially available for designs up to 1m aperture diameter. The prototype operates via wireless connection to single-board computers (SBCs) resident within the enclosure that accept commands and report telemetry and data products to a computer external to the enclosure. These SBCs run Debian 9 hosting control software written in C++ and compiled under GCC. All hardware is connected and controlled via USB, and the prototype draws a total of 35W during operation.
Aerospace’s digital and material implementations are designed to scale up for geographical distribution. The Prime Focus digital solution scales through replication of software and storage implemented via cloud-native technologies. The Monocle material solution scales through replication of an autonomous, low-SWaP ground station composed of COTS components. From these implementations, a geographically dispersed ground network may be realized by mounting Monocle units on cell towers to provide power and low-latency communications to a digital backplane. Cell towers are independently owned, rent space to cell carriers, and offer ~1 million potential insertion points distributed throughout the world based simply on the number of cell towers currently in existence. Geographically diversified proliferation of Monocle units provides resiiliency to weather outage, offers line of sight diversity, and allows for observational capacity that scales to arbitrary sensor count. Controlling this sensor network via network data centers operating under the Prime Focus model via the cell network permits dynamic, low-latency scheduling and data retrieval.
Aerospace propses this autonomous, ground sensor network to address the problems of capacity and timeliness arising from the RSO vs sensor scaling law mismatch. Left unaddressed, this mismatch may grow to jeopardize the activities of space control, space domain awareness and space traffic management.
Date of Conference: September 27-20, 2022
Track: SSA/SDA