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Lightsey,
E. Glenn
Lightsey,
E. Glenn
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ItemDesign of the Hosted Software Application for the VISORS Mission(Georgia Institute of Technology, 2023-08) Arunkumar, Ebenezer ; Paletta, Antoine ; Lightsey, E. GlennThe VIrtual Super Optics Reconfigurable Swarm (VISORS) mission is a distributed space telescope consisting of two 6U CubeSats that utilize precision formation flying to detect and study the fundamental energy release regions of the solar corona. The inherent complexities and risks associated with two spacecraft operating in close proximity, as well as the unique restrictions of the spacecrafts’ design, make careful autonomous execution crucial to the success of the mission. To address these challenges, this paper outlines the development of the Hosted Software Application (HSA) flight software which manages the Guidance, Navigation, and Control (GNC) algorithms, the payload finite state machine, and the spacecraft and formation level fault management system. An overview of the HSA provides context for the motivation and requirements driving the design of the flight software system. The architecture of the HSA is presented and shown to be derived from the Mission Events Timeline (MET) for each of the relevant phases of the mission. Finally, this paper briefly discusses the software's implementation and test campaign.
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ItemDevelopment of an Autonomous Distributed Fault Management Architecture for Spacecraft Formations Involving Proximity Operations(Georgia Institute of Technology, 2023-08) Paletta, Antoine ; Arunkumar, Ebenezer ; Lightsey, E. GlennCubeSat formations have been identified as a new paradigm for addressing important science questions but are often early adopters of new technologies which carry additional risks. When these missions involve proximity operations, novel fault management architectures are needed to handle these risks. Building on established methods, this paper presents one such architecture that involves a passively safe relative orbit design, interchangeable chief-deputy roles, a formation level fault diagnosis scheme, and an autonomous multi-agent fault handling strategy. The primary focus is to enable the reliable detection of faults occurring on any formation member in real time and the autonomous decision making needed to resolve them while keeping the formation safe from an inter-satellite collision. The NSF-sponsored Virtual Super-resolution Optics with Reconfigurable Swarms (VISORS) mission, which consists of two 6U CubeSats flying in formation 40 meters apart as a distributed solar telescope, is used as a case study for the application of this architecture. The underlying fault analysis, formulation of key elements of the fault detection and response strategies, and the flight software implementation for VISORS are discussed in the paper.
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ItemTesting Methodology For Spacecraft Precision Formation Flying Missions(Georgia Institute of Technology, 2023-02) Kimmel, Elizabeth ; Paletta, Antoine ; Arunkumar, Ebenezer ; Krahn, Grace ; Lightsey, E. GlennDistributed space systems, and specifically spacecraft formations, have been identified as a new paradigm for addressing important science questions. However, when it comes to verifying and validating these systems before launch, there is the added challenge of figuring out how to test the formation's holistic operations on the ground since a full end-to-end mission simulation is likely infeasible due to the need for costly testing infrastructure/facilities. Building on established methods for single-spacecraft testing, this paper presents a two-phase testing methodology that can be applied to precision formation flying missions with budget, timeframe, and resource constraints. First, a testing plan with unique considerations to address the coordinated and coupled nature of precision formation flight is devised to obtain high system confidence on the ground, and second, the formation's holistic behavior is refined on orbit during the mission's in-space commissioning. This approach structures the pre-launch testing to make efficient use of the limited test infrastructure on hand and leverages a sequential configuration process combined with built-in operational flexibility on orbit to safely finish characterizing the formation's performance so that it can meet mission requirements.
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ItemConcept of Operations for the VISORS Mission: A Two Satellite Cubesat Formation Flying Telescope(Georgia Institute of Technology, 2022-02) Lightsey, E. Glenn ; Arunkumar, Ebenezer ; Kimmel, Elizabeth ; Kolhof, Maximilian ; Paletta, Antoine ; Rawson, William ; Selvamurugan, Shanmurugan ; Sample, John ; Guffanti, Tommaso ; Bell, Toby ; Koenig, Adam ; D'Amico, Simone ; Park, Hyeongjun ; Rabin, Douglas ; Daw, Adrian ; Chamberlin, Phil ; Kamalabadi, FarzadThe Virtual Super-resolution Optics with Reconfigurable Swarms (VISORS) is a National Science Foundation (NSF) space physics mission which will detect and study fundamental energy-release regions in the solar corona. The VISORS mis-sion will image extreme ultraviolet (EUV) features on the Sun at a resolution of at least 0.2 arcseconds from Low Earth Orbit (LEO). To accomplish this objective, VISORS will use a pair of formation flying 6U CubeSats: one of which carries the observatory optics while the other contains the detector instrument. VISORS will serve as a proof of concept for this distributed instrument approach by obtaining at least one 10-second exposure image during its six-month mission life-time. Meeting the strict relative orbit requirements during science observations will demonstrate several technologies key to precise formation flying including intersatellite link, relative navigation, and autonomous maneuver planning. To satisfy these stringent mission requirements, a concept of operations has been established that requires maneuvering between a standby orbit where housekeeping tasks are performed and an actively maintained science orbit where observations are conducted. Formation acquisition, re-acquisition, fault recovery, and escape operations are also planned. This paper provides a description of the VISORS formation flying concept of operations: explaining the function and rationale of each operation mode, how these modes are designed, and how they collectively meet the mission requirements. Specific challenges and mission trades related to performing precision formation flight with CubeSats are discussed. A Failure Mode Effects and Criticality Analysis (FMECA) is conducted to assess the risk of collision under the most probable fault scenarios, which is used to inform the development of operational mitigation strategies and on-board fault tolerant collision avoidance (COLA) logic.