Thermal Vacuum Test Campaign of the EIRSAT-1 Engineering Qualification Model

Abstract

CubeSats facilitate rapid development and deployment of missions for educational, technology demonstration, and scientific purposes. However, they are subject to a high failure rate, with a leading cause being the lack of system-level verification. The Educational Irish Research Satellite (EIRSAT-1) is a CubeSat mission under development in the European Space Agency’s (ESA) Fly Your Satellite! Programme. EIRSAT-1 is a 2U CubeSat with three novel payloads and a bespoke antenna deployment module, which all contribute to the complexity of the project. To increase the likelihood of mission success, a prototype model philosophy is being employed, where both an engineering qualification model (EQM) and a flight model of EIRSAT-1 are being built. Following the assembly of the EQM, the spacecraft underwent a successful full functional test and month-long mission test. An environmental test campaign in ESA Education Office’s CubeSat Support Facility was then conducted with the EQM where both vibration and thermal verification test campaigns were performed. The focus of this paper is the thermal testing and verification of the EIRSAT-1 EQM. Over three weeks, the EQM was subjected to one non-operational cycle, three and a half operational cycles, and a thermal balance test in a thermal vacuum chamber. After dwelling at each temperature extreme, functional tests were performed to investigate the performance of the spacecraft in this space representative environment. The approach to planning and executing the thermal testing is described in detail including the documentation required, set up of the test equipment, and determination of the test levels. Overall, the campaign demonstrated that the mission can successfully operate in a space environment similar to that expected in orbit, despite encountering a number of issues. These issues included a payload displaying anomalous behaviour at cold temperatures and needing to redefine test levels due to an insufficient understanding of the internal dissipation in the spacecraft. A total of two major and three minor non-conformances were raised. Crucially, these issues could not have been found without thermal testing, despite the comprehensive ambient tests performed. The main results and lessons learned during this thermal test campaign are presented with the aim of guiding future missions on optimal approaches in organising and executing the thermal testing of their CubeSats.

Design, development and testing of flight software for EIRSAT-1: a university-class CubeSat enabling astronomical research

“…Environmental testing: in which the satellite is subject to representative spaceflight conditions, including vibration and thermal vacuum testing, with functional checks prior to, during, and after the tests 68 …”

Experiences in firmware development for a CubeSat instrument payload

“…Throughout the design and qualification stage of the life cycle, the spacecraft and payloads undergo numerous tests. Environmental testing may be conducted on the subsystem [4] and system level [8], which may also require pre-campaign functional and mission tests [9]. All of these tests can be used to inform additions or amendments to the existing functionality, providing feedback not found within the scope of the basic payload firmware requirements.…”

Update on the status of the Educational Irish Research Satellite (EIRSAT-1)

“…Umbilical cables and thermocouples allowed communication with and monitoring of the EQM while in this test set-up. During TVAC testing, the spacecraft was subjected to a vacuum of ~10 -6 mbar, and temperatures ranging from −26°C to +56°C, while powered off, and −26 °C and +36.5 °C, while powered on [14]. When powered on, health checks were performed to ensure all subsystems functioned nominally under TVAC conditions.…”

“…Excluding GMOD (for which health checks were modified to better assess the scope of the damage experienced during vibration testing), the EQM largely performed as expected throughout TVAC testing, providing confidence that the EIRSAT-1 spacecraft can survive the space environment. Minor anomalies that were encountered were either related to the test setup or functions of the flight software which were impacted by the temperature conditions [14].…”