Allen Wautlet, BAE Systems; Justin Kim, BAE Systems; Michael Veto, BAE Systems; Matthew Tooth, BAE Systems; Raymond Wright, BAE Systems; Jared Steffen, University of Colorado Boulder
Keywords: LEO, SDA, LWIR, Visible, Architecture
Abstract:
Space Domain Awareness (SDA) in Low Earth Orbit (LEO) continues to be of interest to commercial and government parties due to rapid growth in this regime. The proliferation of small satellites, debris, distributed commercial constellations, and nation state satellites in LEO drives the need for architectures that provide timely and accurate measurements of satellite states for safety and tracking. Architectures that augment existing collection techniques will close the gap in observations that exist in current systems, and distributed payloads that exploit underutilized parts of the spectrum will provide end users more actionable and timely knowledge of changes in orbit. The design of these architectures and their relative strengths and weaknesses are of great interest to the community, and present opportunities to expand the community’s vision in this space.
SDA observations of LEO objects are typically done in the visible light portion of the spectrum, which is constrained by collection method and viewing geometry. Ground-based telescopes provide global coverage, but gaps exist where land is not available due to physical or environmental limitations. In addition, ground-based telescopes present limitations on atmospheric conditions, light pollution, field of view, and target lighting conditions. Moving observations to space in the visible spectrum overcomes many geographic and atmospheric limitations while presenting other lighting and geometry challenges to a sensor network. The median LEO object spends over 30% of its time in shadow and frequently presents bad solar phase angles to space-based observers, which creates significant gaps in custody of a particular object. These constraints create gaps in sensing the LEO regime that hamper safety and management of that domain.
Sensing in the longwave infrared (LWIR) portion of the spectrum allows an architecture to view objects that are in shadow, as thermal emissions from these objects provide signal throughout their orbits. Use of these sensors has been limited in the past due to constraints in cost and logistics, but the overall costs of LWIR payloads have been significantly reduced in recent years. While these sensors can be deployed in both space and ground architectures, ground-based observations with LWIR are constrained by geographic location, atmospheric conditions, and atmospheric absorption. A space-based LWIR architecture is not limited by these conditions and is able to sense objects that are both sun-lit and in shadow.
This paper describes the design considerations for creating a LEO LWIR architecture and the relative improvements in coverage and state knowledge that these elements could provide. A variety of classes of LWIR payloads are modeled to represent a range of sensor performance in a hypothetical constellation of satellites. Performance of architectures hosting these payloads is traded using varying orbital heights, orbital inclinations, and payload pointing directions. Positional knowledge and revisit time against a hypothetical LEO satellite deck with additional simulated debris objects is explored for a selected series of architecture designs along with a discussion of variables that most influenced the outcomes of this study. The strengths of fusing the data from an LWIR architecture with existing ground sites and visible observations are also explored.
Date of Conference: September 16-19, 2025
Track: SDA Systems & Instrumentation