Now showing 1 - 4 of 4
  • Publication
    Development of the Ground Segment Communication System for the EIRSAT-1 CubeSat
    The Educational Irish Research Satellite (EIRSAT-1) is a student-led project to design, build and test Ireland’s first satellite. As part of the development, a ground segment (GS) has also been designed alongside the spacecraft. The ground segment will support two-way communications with the spacecraft throughout the mission. Communication with the satellite will occur in the very high frequency (VHF) and the ultra high frequency (UHF) bands for the uplink and downlink respectively. Different modulation schemes have been implemented for both uplink and downlink as part of the GS system. Uplink incorporates an Audio Frequency Shift-Keying (AFSK) scheme, while downlink incorporates a Gaussian Minimum Shift-Keying (GMSK) scheme. In order for the spacecraft to successfully receive a telecommand (TC) transmitted from the ground station, a framing protocol is required. AX.25 was selected as the data link layer protocol. A hardware terminal node controller (TNC) executes both the AX.25 framing and the AFSK modulation. Keep It Simple Stupid (KISS) framing software was developed to allow data to be accepted by the TNC. A software defined radio (SDR) approach has been chosen for the downlink. GNURadio is software that allows flowcharts to be built to undertake the required signal processing of the received signal, the demodulation of the signal and the decoding of data. This paper provides a detailed account of the software developed for the ground segment communication system. A review of the AX.25 and KISS framing protocols is presented. The GNURadio flowcharts that handle the signal processing and data decoding are broken down and each constituent is explained. To ensure the reliability and robustness of the system, a suite of tests was undertaken, the results of which are also presented.
      693
  • Publication
    Update on the status of the Educational Irish Research Satellite (EIRSAT-1)
    The Educational Irish Research Satellite, EIRSAT-1, is a 2U CubeSat being implemented by a student-led team at University College Dublin, as part of the 2nd round of the European Space Agency’s Fly Your Satellite! programme. In development since 2017, the mission has several scientific, technological and outreach goals. It will fly an in-house developed antenna deployment module, along with three custom payloads, which are integrated with commercial off-the-shelf subsystems. In preparation for the flight model, a full-system engineering qualification model of the spacecraft has undergone an extensive period of test campaigns, including full functional tests, a mission test, and environmental testing at the European Space Agency’s CubeSat Support Facility in Redu, Belgium. Beyond the technical, educational, and capacity-building goals of the mission, EIRSAT-1 aims to inspire wider study of STEM subjects, while highlighting the importance of multidisciplinary teams and creating greater awareness of space in everyday life. A wide range of outreach activities are being undertaken to realise these aims. This paper provides a status update on key aspects of the EIRSAT-1 project and the next steps towards launch.
      27
  • Publication
    Development and Validation of the Operations Procedures and Manual for a 2U CubeSat, EIRSAT-1, with Three Novel Payloads
    The CubeSat standard, relatively short launch timescale, and orders of magnitude difference in cost in comparison to large scale missions, has allowed universities and smaller institutions to develop space missions. The Educational Irish Research Satellite (EIRSAT-1) is a 2U CubeSat being developed in University College Dublin (UCD) as part of the second round of the European Space Agency (ESA) Education Office’s Fly Your Satellite! (FYS) Programme. EIRSAT-1 is a student-led project to build, test, launch and operate Ireland’s first satellite. CubeSats typically use commercial off-the-shelf (COTS) components to facilitate new teams in developing a satellite on a rapid timescale. While some of the EIRSAT-1 subsystems are COTS procured from AAC Clyde Space, EIRSAT-1 has three novel experiments on-board which have been developed in UCD. The spacecraft’s Antenna Deployment Module has also been designed and built in-house. The on-board computer (OBC), procured from AAC Clyde Space, has been adapted to interface with these novel hardware components, accompanied by in-house developed software and firmware. All of these innovative subsystems complicate the CubeSat functionality making it essential to document and rigorously test the operations procedures for EIRSAT-1. In preparation for launch with these novel spacecraft subsystems, the EIRSAT-1 Operations Manual is being developed and incrementally verified. The Operations Manual contains the procedures to command and control the satellite, account for nominal and non-nominal scenarios and guide the operator in determining the cause of any anomalies observed during the mission and facilitate recovery. A series of operations development tests (ODTs) have been designed and conducted for a robust verification process. Each procedure is written up by a member of the EIRSAT-1 Operations Team in the EIRSAT-1 Operations Manual format. During an ODT, an in-flight scenario is considered in which the procedure under test is required. The procedure is then followed by a team member who has not been involved in the procedure development process. The feedback from these tests and from the operators is used to improve the procedures and continually update the Operations Manual. This paper will present the approach to operations development used by the EIRSAT-1 team and discuss the lessons learned for CubeSat operations development, testing and pre-flight verification.
      484
  • Publication
    Hardware and Embedded Firmware Development of a Gamma-Ray Burst Detector for a 2U CubeSat
    (University College Dublin. School of Physics, 2022)
    Gamma-ray bursts (GRBs) are among the most extreme energetic events in the universe and represent the death knell of massive stars and compact objects. In one scenario, a massive and ancient star has burnt through its fuel reserve resulting in a core collapse event, a supernova. In the other, massive compact binary objects, like black hole - black hole (BH-BH), neutron star - black hole (NS-BH) and NS-NS pairs coalesce through merger events caused by the radiation of gravitational energy. In both cases a GRB may be observed. If the object is orientated just right, a beamed emission directed towards Earth may be detectable as a sudden, intense but brief flash of gamma-ray photons with a later afterglow emission observable in longer wavelengths for days to weeks after the initial event. The advent of gravitational wave astronomy as a multi-messenger for high-energy astrophysical phenomena, along side recent advancements towards the miniaturisation of detector technology, have made it possible for CubeSat missions to perform cost-effective and fruitful science. Furthermore, widely accessible commercial-off-the-shelf hardware allows small non-agency institutions and universities to build robust missions with custom payloads for technology demonstrations and to contribute to the aims of the scientific community alongside traditional flagship missions. The Gamma-Ray Module (GMOD) is a CubeSat compatible, scintillation based gamma-ray detecting instrument, with dimensions <1U (less than 10 cm x 10 cm x 10 cm). GMOD has been developed primarily for the detection of GRBs and other high-energy electromagnetic phenomena from Earth orbit. This thesis will introduce GMOD through its origin, development and testing, its mission objectives and future outlook, all with respect to the astrophysical context of current high-energy astronomy and instrumentation. During its mission, GMOD will experience the mechanical stresses induced during its launch, deployment and the sustained thermal and radiation effects of the harsh space environment. Furthermore, the instrument firmware will be expected to perform over long durations, often operating continuously for weeks on end. The instrument must be capable of performing effectively and to operate continually without disruption to the handling of science data. To achieve this, several tests have been conducted including a high altitude balloon flight, SiPM irradiation testing, subsystem thermal vacuum and vibration testing and a full benchmarking of the firmware performance and response to simulated GRB events. The GMOD hardware has been fully tested in accordance with European Space Agency standards and the firmware has been rigorously assessed, while the methodology has been subject to peer-review. GMOD has been accepted for flight and will be flown in 2023 onboard EIRSAT-1, Ireland’s first satellite, with an expected detection yield of ~11–14 GRB triggers at 10σ significance. Once in operation, GMOD will contribute to the high-energy astronomy community and will be a demonstrator for future GRB detecting instruments.
      22