The paper presents the initial outcomes of a project, currently ongoing under the supervision of the European Space Agency, having the main objective to specify and design a Fault Detection Isolation and Recovery (FDIR) system by making use of relevant RAMS (Reliability, Availability, Maintainability, Safety) analyses for missions in non-deterministic environment with limited resources. The initial project tasks have been to select a study case represented by a CubeSat complex mission, analyse in detail both its mission and system requirements and, based on them, define a set of relevant RAMS analyses to be carried out in the second phase of the project, as inputs for the development of a FDIR concept aimed at a careful balance of the limited spacecraft resources in case of critical failures. Two possible study cases have been identified: LUMIO, a 12U CubeSat mission for the observation of micro-meteoroid impacts on the Lunar farside, and M-ARGO, a 12U deep-space CubeSat which will rendezvous with a near-Earth asteroid and characterize its physical properties for the presence of in-situ resources. Although both missions are characterized by a high level of autonomy and complexity in a harsh environment, LUMIO has been eventually selected as study case for the project. In the paper, the challenges and features of this mission are shortly presented. The specificities of the RAMS analysis and FDIR concept for this specific class of small satellite missions (including the selected study case) are highlighted in the paper, looking in particular at aspects such as the improvement of reliability while maintaining the CubeSat philosophy, the tuning of mission and system requirements in view of facilitating the design and implementation of the FDIR concept, and the current gaps within the RAMS/FDIR body of knowledge. The conclusions drawn during this first project phase provide a real view of how systems engineering must work in tandem with RAMS analyses and FDIR to achieve a more robust and functional mission architecture, thus improving the mission reliability.

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The Earth-Moon system is constantly bombarded by meteoroids of different size and impact speed. Observation of the impacts on the Moon can enable thorough characterization of the Lunar meteoroid flux, which is similar to that of the Earth. While Earth-based Lunar observations are restricted by weather, geometric and illumination conditions, a Lunar-based observation campaign can improve the detection rate and, when observing the Lunar far side, complement in both space and time the observations taken from Earth. The Lunar Meteoroid Impact Observer (LUMIO), one of the two winning concepts of the ESA SysNova Lunar CubeSats for Exploration challenge, is a mission designed to observe, quantify, and characterize the micro-meteoroid impacts on the Lunar far side. It is based on a 12U CubeSat that carries the LUMIO-Cam, a custom-designed optical instrument capable of detecting light flashes in the visible spectrum. The spacecraft is placed on a halo orbit about the Earth–Moon L2 point, where permanent full-disk observation of the Lunar far side can be performed with excellent quality, given the absence of Earth background noise. After passing Phase 0 and an independent feasibility study in the ESA Concurrent Design Facility, the mission has successfully completed its Phase A in March 2021. Although the Phase 0 design of the LUMIO spacecraft was assessed as feasible by the ESA CDF study, a number of critical issues were identified, which have been tackled by the Phase A design. The paper presents the outcome of this Phase A design effort for the LUMIO spacecraft. Particularly relevant changes or updates in the spacecraft design include: a consolidated design of the LUMIO-Cam, with longer baffle for straylight protection; a set of ADCS sensors and actuators with increased redundancy; a combination of Direct-to-Earth communication and inter-satellite link with a mothership in Lunar orbit; use of Earth ranging to complement and validate the current innovative autonomous navigation strategy based on optical observations of the Moon by means of the LUMIO-Cam; re-assessment of the COTS components selection for the power and propulsion systems. @en

The Lunar Meteoroid Impact Observer (LUMIO) is a mission designed to observe, quantify, and characterize the impacts of meteoroids on the lunar far side and, therefore, complement in both space and time the observations currently taken from Earth. While Earth-based lunar observations are restricted by weather, geometric and illumination conditions, a Moon-based observation campaign can improve the detection rate of impact flashes and the general quality and reliability of the final scientific product. The mission has successfully completed the Phase A design, after successfully passing Phase 0 and an independent study in the ESA Concurrent Design Facility that has fully confirmed its feasibility. The LUMIO spacecraft is a 12U XL CubeSat with a mass of around 28 kg, released into Lunar orbit by a carrier spacecraft and capable of autonomously transferring from this initial parking orbit to its final destination, a halo orbit about the Earth–Moon L2 point from which permanent fulldisk observation of the Lunar far side can be performed. The mission objectives will be achieved thanks to the LUMIO-Cam, a custom-designed optical instrument capable of detecting light flashes in the visible spectrum, and an innovative on-board data processing system, capable of drastically reducing the amount of information that needs to be transmitted back to Earth. The camera is capable of generating 5TBd−1 of data, out of which only approximately 1MBd−1 will need to be transmitted to Earth, since impact identification will be performed autonomously onboard and only relevant information will be actually transmitted. This paper will present the current status of the mission, summarising the main results of the Phase A design and the way forward to the following steps in mission implementation (Phases B-C). The paper will include a summary of the spacecraft system design and mission analysis. Particular focus will be given to the mission operations aspects. @en

The LUnar Meteoroid Impacts Observer (LUMIO) is a CubeSat mission to a halo orbit at Earth–Moon L2 that shall observe, quantify, and characterize meteoroid impacts on the Lunar farside, by detecting their flashes. In this way, LUMIO is expected to significantly contribute to Lunar Situational Awareness and to the current knowledge on the evolution of meteoroids in the cislunar space. This will allow, ultimately, to achieve a better understanding of the origins of the Solar System, the composition of its planets and the possible hazards caused by impacts between the Earth and Near Earth Objects. LUMIO was one of the proposals submitted to the SysNova LUnar CubeSats for Exploration call by the European Space Agency. The mission was awarded ex-aequo winner of the challenge, and its scientific relevance and technical feasibility were confirmed by an independent study conducted by the ESA Concurrent Design Facility. The LUMIO Phase A study is currently ongoing and is scheduled for completion by the end of 2020. This paper, after providing a short overview of the scientific relevance of the mission, presents in detail the status of the current LUMIO Phase A study, including an overview of all spacecraft sub-systems and the evolution of their design from Phase 0 to Phase A. @en

Mars Atmospheric Radiation Imaging Orbiter (MARIO) is a 16U stand-alone CubeSat mission that shall escape Earth, perform autonomous deep-space cruise, achieve ballistic capture, and enter an operational orbit at Mars to perform thermal radiation imaging. This work focuses on the systems design of MARIO. The design of combined chemical-electric propulsion systems, comprising FLP-106 based green chemical monopropellant thruster and the iodine-fueled RF ion thruster, for hybrid high-thrust-low-thrust Earth-Mars transfer is presented. Reflectarrays along with high-gain antennas are utilised to establish long-distance low-bandwidth X-band communication link with the Earth. Electrical power system design is pursued to provide steady power to the system during the transfer and science operations phases. A novel autonomous navigation strategy is proposed which includes horizon-based optical navigation near target bodies and deep-space line-of-sight navigation for accurate state estimation for autonomous operations. Details regarding on-board processing, attitude determination, and thermal control are delineated. Feasible budgets for mass and communications link are obtained. The structural composition of MARIO is detailed.

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