KEYWORDS: Space operations, Gamma radiation, Data communications, Satellites, Frequency modulation, Fermium, Data storage, Education and training, Equipment, Windows
CubeSats provide opportunities for science and technology demonstration missions with low-cost solutions and short project timescales, in particular, for studying gamma-ray bursts (GRBs) in the multi-messenger era. A robust operations strategy for scientific CubeSat projects is key to optimizing the results obtained from the experimental instruments. The Educational Irish Research Satellite-1 (EIRSAT-1) is a 2U CubeSat with three payloads, including a bespoke gamma-ray detector, gamma-ray module (GMOD), developed in-house for the detection of GRBs. The detection and reporting of GRB triggers to the scientific community complicates and drives the mission operational strategy. The operational procedures developed for commissioning and operating GMOD are detailed. The successful operation of EIRSAT-1 will facilitate the detection of ∼15 GRBs / year in low Earth orbit. To increase the likelihood of mission success, the project is following a prototype model philosophy, building, and testing, both an engineering qualification model (EQM) and flight model. The EIRSAT-1 operations manual is the document that will instruct operators in commanding the spacecraft correctly and efficiently throughout the mission lifetime. The operations manual must be refined in parallel to payload development. This two-model philosophy has provided time for the early development of the EIRSAT-1 operations manual with the EQM. The EIRSAT-1 operations manual has undergone incremental updates based on feedback from operational development tests (ODTs), and a version with 35 procedures was frozen prior to the month-long EQM mission test (MT). Specifically, the objective of our work is to validate and refine the operations manual using the EQM MT process. Although the ODTs were effective preparation, the MT process highlighted issues, such as procedures operators found convoluted, and scenarios not yet considered during the initial development stages. Two new procedures were identified, 8 procedures required major updates, 15 required minor updates, and the remaining 12 required no improvements after the MT. The validation process facilitated operator training in mission representative conditions, such as GRB triggering data downlink with GMOD, and the major lessons learned during the development and validation process are presented.
KEYWORDS: Software development, Design and modelling, Space operations, Satellites, Antennas, Windows, Gamma radiation, Commercial off the shelf technology, Analog to digital converters, Astronomy
The capabilities of CubeSats have grown significantly since the first of these small satellites was launched in the early 2000s. These capabilities enable a wide range of mission profiles, with CubeSats emerging as viable platforms for certain space-based astronomical research applications. The Educational Irish Research Satellite (EIRSAT-1) is a CubeSat being developed as part of the European Space Agency’s Fly Your Satellite! program. In addition to its educational aims, the mission is driven by several scientific and technological goals, including goals related to a novel gamma-ray instrument for the detection of bright transient astrophysical sources, such as gamma-ray bursts. This work provides a detailed description of the software development life-cycle for EIRSAT-1, addressing the design, development and testing of robust flight software, aspects of payload interfacing, and risk mitigation. The described design-to-testing approach was implemented to establish, prior to launch, that EIRSAT-1 can perform its intended mission. Constraints and challenges typically experienced by CubeSat teams, which can impact the likelihood of mission success, are considered throughout this work, and lessons learned are discussed. The aim of this work is to highlight the advanced capabilities of CubeSats while providing a useful resource for teams implementing their own flight software.
The gamma-ray module on EIRSAT-1 is a <1U CubeSat compatible instrument for the detection of high energy transient events, primarily intended for low earth orbit detection of gamma-ray bursts. The compact and low power nature of the design makes GMOD a novel instrument for GRB detection on a 2U CubeSat. The GMOD motherboard provides support to the instrument by managing a number of operation critical duties, most importantly the reliable execution of the experiment, temporary onboard flash storage and transfer of time tagged event readout to the EIRSAT-1 on-board computer. Executing these tasks is the TI MSP430FR5994 microcontroller which is loaded with a custom firmware developed for the instrument motherboard. A recent investigation into the firmware performance at fixed trigger rates proved that the firmware concept was viable for reliable detector readout. We present an investigation carried out to further quantify the performance of the firmware in a more realistic operational mode. These tests accurately simulate the rates expected by GMOD during detection of GRBs and measure performance by comparing the expected output to the actual instrument output. This is done by externally triggering the detector readout to mimic the expected rates for a range of GRB profiles and expected fluxes derived from the 4th Fermi GBM catalogue. This work evaluates the flight model firmware performance for a sample of 40 GRBs spanning a range of peak fluxes and durations.
The capabilities of CubeSats have grown significantly since the first of these small satellites was launched in the early 2000s. These capabilities enable a wide range of mission profiles, with CubeSats emerging as viable platforms for certain space-based astronomical research applications. The Educational Irish Research Satellite (EIRSAT-1) is a CubeSat being developed by a student-led team as part of the European Space Agency’s Fly Your Satellite! programme. In addition to its educational aims, the mission is driven by several scientific and technological goals, including a novel gamma-ray instrument for the detection of bright transient astrophysical sources such as gamma-ray bursts. This work provides a detailed description of the software development lifecycle for EIRSAT-1, addressing the design, development and testing of robust flight software, aspects of payload interfacing, and risk mitigation. A design-to-testing approach has been implemented in order to establish, prior to launch, that EIRSAT-1 can perform its intended mission. Constraints and challenges typically experienced by CubeSat teams, which can impact the likelihood of mission success, have been considered throughout and lessons learned are discussed. The aim of this work is to highlight the advanced capabilities of CubeSats while also providing a useful resource for other university-based teams implementing their own flight software.
KEYWORDS: Space operations, Gamma radiation, Sensors, Data storage, Data communications, Satellites, Antennas, Signal processing, Satellite communications
CubeSats provide opportunities for science and technology demonstration missions with low-cost solutions and short project timescales, in particular, for studying gamma-ray bursts (GRBs) in the multi-messenger era. A robust operations strategy for scientific CubeSat projects is key to optimising the results obtained from the experimental instruments. The Educational Irish Research Satellite (EIRSAT-1) is a 2U CubeSat with three novel payloads, including a bespoke gamma-ray detector, GMOD, developed in-house for the detection of GRBs. The detection and reporting of GRB triggers to the scientific community complicates and drives the mission operational strategy. The operational procedures developed for commissioning and operating GMOD are detailed. The successful operation of EIRSAT-1 will facilitate the detection of ∼15 GRBs/year in low earth orbit. To increase the likelihood of mission success, the project is following a prototype model philosophy, building and testing, both an Engineering Qualification Model (EQM) and Flight Model (FM). The EIRSAT-1 operations manual is the document that will instruct operators in commanding the spacecraft correctly and efficiently throughout the mission lifetime. The operations manual must be refined in parallel to payload development. This two-model philosophy has provided time for the early development of the EIRSAT-1 operations manual with the EQM. The EIRSAT-1 operations manual has undergone incremental updates based on feedback from Operational Development Tests (ODTs) and a version with 35 procedures was frozen prior to the month-long EQM mission test (MT). Specifically, the objective of this work is to validate and refine the operations manual using the EQM MT process. Although the ODTs were effective preparation, the MT process highlighted issues such as procedures operators found convoluted, and scenarios not yet considered during the initial development stages. Two new procedures were identified, eight procedures required major updates, fifteen required minor updates and the remaining twelve required no improvements after the MT. The validation process facilitated operator training in mission representative conditions, such as GRB triggering data downlink with GMOD, and the major lessons learned during the development and validation process are presented.
CubeSats are a small satellite technology that first emerged in the space sector in the early 2000s. Their low-cost, fast-delivery design has made space more accessible, leading to a significant increase in the number of satellites launched per year as well as the number of nations launching satellites. As an example, the Educational Irish Research Satellite, EIRSAT-1, is a CubeSat being developed by a student-led team at University College Dublin, aiming to launch Ireland’s first satellite. Originally viewed as educational tools, the capabilities of CubeSats to satisfy a wide range of aims, from technology demonstration to Earth observation and scientific aims, is growing as these satellite platforms advance. However, following two decades of launches, an issue still facing their success as a disruptive technology is the high failure rate of CubeSats. This is a result of the CubeSat design philosophy where, in lieu of challenging resource demands, higher levels of risk are more acceptable compared to conventional space missions. In an effort to reduce these risks, this work presents an overview and highlights the benefits of a testing technique, known as Mission Testing. Mission Testing differs from other satellite testing in that flight representative conditions are simulated during the test. This aspect of the test mitigates risks not addressed elsewhere, such as risks related to the order and duration of operations, and also offers a number of unique benefits, such as operations training for the Mission Control Team. As part of this work, results of a survey disseminated to CubeSat teams are presented, where the aspects of Mission Testing considered most valuable and lessons learned in light of on-orbit operations are identified. How these results have helped shape the Mission Test plans for the EIRSAT-1 mission are also discussed and overview of the test plans are presented. In addition to the benefits for EIRSAT-1, this study aims to provide a resource for CubeSat teams in general, wanting to improve mission reliability through comprehensive Mission Testing.
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