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.
Space Debris removal is a critical issue related to space research. One of the key requirements for a removal mission is the assessment of the target rotational dynamics. Ground observations are not sufficient for reaching the accuracy level required to guide the chaser spacecraft during the capture maneuver. Moreover, the guidance and control strategy for the chaser to approach the target is a critical aspect of such missions. This paper present simulation results of two complementary methods, one for estimating the entire rotational dynamic state of the target, and the other for accurately controlling the approach maneuver. In particular, the information coming from the identification and prediction of the actual motion of the rotation axis of the target is exploited by the second method for aligning the docking interface of the chaser with that axis at the instant of capture. The dynamic estimation is based on Kalman filtering in an original combination with compressive sampling techniques for making the method robust to failures of the observation sensors. The guidance of the chaser is based on a model predictive control law. The combined simulation of the employment of the methods has revealed the feasibility of the global approach.
I. .IntroductionNE of the main concerns in the space field is the high number of objects orbiting the Earth in orbits of interest for the accomplishment of scientific and communication missions. Currently, more than 10000 objects bigger than 10 cm take up Low Earth Orbit (LEO) and Geosynchronous Earth Orbit (GEO) [1].
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