Special Issue "Verification Approaches for Nano- and Micro-Satellites"

A special issue of Aerospace (ISSN 2226-4310).

Deadline for manuscript submissions: closed (31 October 2019).

Special Issue Editors

Prof. Dr. Paolo Tortora
Website
Guest Editor
Dipartimento di Ingegneria Industriale, Alma Mater Studiorum Università di Bologna, Bologna, Italy
Interests: small satellites; innovative spacecraft subsystems including the ground segment; planetary exploration with particular reference to radio science experiments
Special Issues and Collections in MDPI journals
Prof. Dr. Dario Modenini
Website
Guest Editor
Dipartimento di Ingegneria Industriale, Alma Mater Studiorum Università di Bologna, Bologna, Italy
Interests: design and testing in the field of microsatellites and space microsystems; methods for attitude determination and control; recursive filters; micropropulsion systems; test-bench for attitude determination and control systems of small satellites
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

There is growing interest for the development of light, small, high-performance spacecraft (S/C) platforms for a wide range of missions. In the early stages of the small-satellite era, both nano-satellites (<10 kg) and micro-satellites (>10 kg) were mainly intended for educational and technology demonstration goals. Nowadays, they are a consolidate means for Earth observation, where they are dramatically reducing the mission costs. We are now at a turning point, where nano-/micro-sat systems can accomplish interplanetary missions beyond the boundaries of LEO orbits (Low Earth Orbits). However, in spite of the substantial increase in low-mass satellites launched since 2013, several statistics show the low success rate of these COTS (commercial off-the-shelf)-based cost-driven systems. Only half of nano-satellites succeeded in mission operations after the successful launch in the last 15 years, but the success rate plunges for larger micro-satellites.

The low success rate of nano-satellites is acceptable, up to a certain extent for educational or technology demonstration missions. This may stem from the way in which university-led projects design and carry out the S/C ground verification process, which lacks repeatability and rigor routinely found in industry. However, despite a nano-satellite is relatively inexpensive, if the S/C is lunched for commercial or scientific exploration purposes, failure is not really an option.

What are the technical challenges and the programmatic difficulties to be faced in order to increase substantially the reliability of nano-/micro-sat missions? The historical causes of low-mass satellite failure can be traced back to (a) lack of system-level testing due to schedule and budget constraints, (b) inadequate thermal design and verification, and (c) use of COTS electronics. Clearly, rigorous ground verification approaches—tailoring the existing testing standards for traditional large/medium-class satellites—are needed to face effectively such challenges.

The topics for this Special Issue include both system analysis for future projects and in-flight experience from ongoing missions. Submission of manuscripts dealing with both subsystem and system-level Assembly Integration and Verification (AIV), with a focus on verification approach, verification methods, verification levels, verification stages, models philosophy and verification tools is encouraged. Papers also are sought which review recent research developments in comprehensive ground verification systems, including not only Software-in-the-Loop (SIL) and component-level Hardware-in-the-loop (HIL) tests, but also system-level HIL tests.

Prof. Paolo Tortora
Prof. Dario Modenini
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Aerospace is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Nanosatellites
  • Microsatellites
  • Assembly Integration and Verification
  • Ground Testing

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Published Papers (12 papers)

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Open AccessEditorial
Verification Approaches for Nano- and Micro-Satellites
Aerospace 2020, 7(4), 40; https://doi.org/10.3390/aerospace7040040 - 08 Apr 2020
Abstract
There is growing interest for the development of light, small, high-performance spacecraft (S/C) platforms for a wide range of missions [...] Full article
(This article belongs to the Special Issue Verification Approaches for Nano- and Micro-Satellites)

Research

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Open AccessArticle
A Dynamic Testbed for Nanosatellites Attitude Verification
Aerospace 2020, 7(3), 31; https://doi.org/10.3390/aerospace7030031 - 18 Mar 2020
Cited by 2
Abstract
To enable a reliable verification of attitude determination and control systems for nanosatellites, the environment of low Earth orbits with almost disturbance-free rotational dynamics must be simulated. This work describes the design solutions adopted for developing a dynamic nanosatellite attitude simulator testbed at [...] Read more.
To enable a reliable verification of attitude determination and control systems for nanosatellites, the environment of low Earth orbits with almost disturbance-free rotational dynamics must be simulated. This work describes the design solutions adopted for developing a dynamic nanosatellite attitude simulator testbed at the University of Bologna. The facility integrates several subsystems, including: (i) an air-bearing three degree of freedom platform, with automatic balancing system, (ii) a Helmholtz cage for geomagnetic field simulation, (iii) a Sun simulator, and (iv) a metrology vision system for ground-truth attitude generation. Apart from the commercial off-the-shelf Helmholtz cage, the other subsystems required substantial development efforts. The main purpose of this manuscript is to offer some cost-effective solutions for their in-house development, and to show through experimental verification that adequate performances can be achieved. The proposed approach may thus be preferred to the procurement of turn-key solutions, when required by budget constraints. The main outcome of the commissioning phase of the facility are: a residual disturbance torque affecting the air bearing platform of less than 5 × 10−5 Nm, an attitude determination rms accuracy of the vision system of 10 arcmin, and divergence of the Sun simulator light beam of less than 0.5° in a 35 cm diameter area. Full article
(This article belongs to the Special Issue Verification Approaches for Nano- and Micro-Satellites)
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Open AccessArticle
Implementation and Hardware-In-The-Loop Simulation of a Magnetic Detumbling and Pointing Control Based on Three-Axis Magnetometer Data
Aerospace 2019, 6(12), 133; https://doi.org/10.3390/aerospace6120133 - 11 Dec 2019
Cited by 3
Abstract
The subject of this work is the implementation and experimental testing of a purely magnetic attitude control strategy, which can provide stabilization after the deployment and pointing of the spacecraft without any attitude information. In particular, the control produces the detumbling of the [...] Read more.
The subject of this work is the implementation and experimental testing of a purely magnetic attitude control strategy, which can provide stabilization after the deployment and pointing of the spacecraft without any attitude information. In particular, the control produces the detumbling of the satellite and leads it to a desired attitude with respect to the direction of the Earth magnetic field, based on the only information provided by a three-axis magnetometer. The system is meant to be used as a backup solution, in case of failure of the primary strategy and is designed considering the constraints set on time of operations, power consumption, and peak electric current for a typical CubeSat mission. The detumbling and pointing algorithms are implemented on the FPGA core of a CubeSat on-board computer and tested by Hardware-in-the-loop simulations. The simulation setup includes a Helmholtz cage, recreating the magnetic environment along the orbit, the on-board computer, a MEMS three-axis magnetometer and Simulink software, on which the attitude dynamics is propagated. Test on the real system can provide useful information to select the parameters of the control, such as the gains, to estimate the limits of the system, the time of operations and prevent failures. Full article
(This article belongs to the Special Issue Verification Approaches for Nano- and Micro-Satellites)
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Open AccessArticle
Integration and Verification Approach of ISTSat-1 CubeSat
Aerospace 2019, 6(12), 131; https://doi.org/10.3390/aerospace6120131 - 01 Dec 2019
Cited by 4
Abstract
Large-scale space projects rely on a thorough Assembly, Integration, and Verification (AIV) process to provide the upmost reliability to spacecraft. While this has not traditionally been the case with CubeSats, their increasing role in space science and technology has led to new verification [...] Read more.
Large-scale space projects rely on a thorough Assembly, Integration, and Verification (AIV) process to provide the upmost reliability to spacecraft. While this has not traditionally been the case with CubeSats, their increasing role in space science and technology has led to new verification approaches, including in educational CubeSats. This work describes the integration and verification approach for ISTSat-1, which is an educational CubeSat from the Instituto Superior Técnico in Portugal that partially discards the typical stage-gate approach to spacecraft development in favor of a more iterative approach, allowing for the system-level verification of unfinished prototypes. Early verification included software functional testing on a flatsat model, thermal vacuum and vibration testing on a battery model, ionizing radiation testing on the on-board computer, and non-ionizing radiation (EMC) testing on all subsystems. The testing of functional prototypes at an early development stage led to uncovering system-level errors that would typically require hardware redesign at a later project stage. The team considers the approach to be useful for educational projects that employ a small, co-located team with low non-recurring engineering costs. Full article
(This article belongs to the Special Issue Verification Approaches for Nano- and Micro-Satellites)
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Open AccessArticle
Hardware-In-The-Loop and Software-In-The-Loop Testing of the MOVE-II CubeSat
Aerospace 2019, 6(12), 130; https://doi.org/10.3390/aerospace6120130 - 01 Dec 2019
Cited by 5
Abstract
This article reports the ongoing work on an environment for hardware-in-the-loop (HIL) and software-in-the-loop (SIL) tests of CubeSats and the benefits gained from using such an environment for low-cost satellite development. The satellite tested for these reported efforts was the MOVE-II CubeSat, developed [...] Read more.
This article reports the ongoing work on an environment for hardware-in-the-loop (HIL) and software-in-the-loop (SIL) tests of CubeSats and the benefits gained from using such an environment for low-cost satellite development. The satellite tested for these reported efforts was the MOVE-II CubeSat, developed at the Technical University of Munich since April 2015. The HIL environment has supported the development and verification of MOVE-II’s flight software and continues to aid the MOVE-II mission after its launch on 3 December 2018. The HIL environment allows the satellite to interact with a simulated space environment in real-time during on-ground tests. Simulated models are used to replace the satellite’s sensors and actuators, providing the interaction between the satellite and the HIL simulation. This approach allows for high hardware coverage and requires relatively low development effort and equipment cost compared to other simulation approaches. One key distinction from other simulation environments is the inclusion of the electrical domain of the satellite, which enables accurate power budget verification. The presented results include the verification of MOVE-II’s attitude determination and control algorithms, the verification of the power budget, and the training of the operator team with realistic simulated failures prior to launch. This report additionally presents how the simulation environment was used to analyze issues detected after launch and to verify the performance of new software developed to address the in-flight anomalies prior to software deployment. Full article
(This article belongs to the Special Issue Verification Approaches for Nano- and Micro-Satellites)
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Open AccessArticle
Validation of a Test Platform to Qualify Miniaturized Electric Propulsion Systems
Aerospace 2019, 6(9), 99; https://doi.org/10.3390/aerospace6090099 - 04 Sep 2019
Cited by 8
Abstract
Miniaturized electric propulsion systems are one of the main technologies that could increase interest in CubeSats for future space missions. However, the integration of miniaturized propulsion systems in modern CubeSat platforms presents some issues due to the mutual interactions in terms of power [...] Read more.
Miniaturized electric propulsion systems are one of the main technologies that could increase interest in CubeSats for future space missions. However, the integration of miniaturized propulsion systems in modern CubeSat platforms presents some issues due to the mutual interactions in terms of power consumption, chemical contamination and generated thermal and electro-magnetic environments. The present paper deals with the validation of a flexible test platform to assess the interaction of propulsion systems with CubeSat-technologies from mechanical, electrical, magnetic, and chemical perspectives. The test platform is a 6U CubeSat hosting an electric propulsion system and able to manage a variety of electric propulsion systems. The platform can regulate and distribute electric power (up to 60 W), exchange data according to several protocols (e.g., CAN bus, UART, I2C, SPI), and provide different mechanical layouts in 4U box completely dedicated to the propulsion system. Moreover, the data gathered by the onboard sensors are combined with the data from external devices and tools providing unprecedented information about the mutual behavior of a CubeSat platform and an electric propulsion system. Full article
(This article belongs to the Special Issue Verification Approaches for Nano- and Micro-Satellites)
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Open AccessArticle
Thermal Numerical Analysis of the Primary Composite Structure of a CubeSat
Aerospace 2019, 6(9), 97; https://doi.org/10.3390/aerospace6090097 - 04 Sep 2019
Cited by 6
Abstract
A thermal computational analysis for the composite structure of a CubeSat is presented. The main purpose of this investigation is to study the thermal performance of carbon fibre/epoxy resin composite materials with Zinc Oxide nanoparticles in order to be used in the panels [...] Read more.
A thermal computational analysis for the composite structure of a CubeSat is presented. The main purpose of this investigation is to study the thermal performance of carbon fibre/epoxy resin composite materials with Zinc Oxide nanoparticles in order to be used in the panels of the primary structure of a CubeSat. The radiative heat fluxes over each composite panel are computed according to the orbit trajectory and they are utilized as boundary conditions for the analysis. The direct solar, albedo and Earth infrared radiation fluxes are considered in this study. The model implementation, including the computation of the orthotropic thermal conductivity of the composite material is presented. The thermal simulations were performed for three different orbit inclination angles: the selected mission ( β = 57 ), the worst hot ( β = 90 ) and the worst cold ( β = 0 ). The temperature ranges in the electronic boards are analyzed in order to show that are into the operating limits of each electronic component. Full article
(This article belongs to the Special Issue Verification Approaches for Nano- and Micro-Satellites)
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Open AccessArticle
Solar Module Integrated Converters as Power Generator in Small Spacecrafts: Design and Verification Approach
Aerospace 2019, 6(5), 61; https://doi.org/10.3390/aerospace6050061 - 27 May 2019
Cited by 6
Abstract
As small satellites are becoming more widespread for new businesses and applications, the development time, failure rate and cost of the spacecraft must be reduced. One of the systems with the highest cost and the most frequent failure in the satellite is the [...] Read more.
As small satellites are becoming more widespread for new businesses and applications, the development time, failure rate and cost of the spacecraft must be reduced. One of the systems with the highest cost and the most frequent failure in the satellite is the Electrical Power System (EPS). One approach to achieve rapid development times while reducing the cost and failure rate is using scalable modules. We propose a solar module integrated converter (SMIC) and its verification process as a key component for power generation in EPS. SMIC integrates the solar array, its regulators and the telemetry acquisition unit. This paper details the design and verification process of the SMIC and presents the in-orbit results of 12 SMICs used in Ten-Koh satellite, which was developed in less than 1.5 years. The in-orbit data received since the launch reveal that solar module withstands not only the launching environment of H-IIA rocket but also more than 1500 orbits in LEO. The modular approach allowed the design, implementation and qualification of only one module, followed by manufacturing and integration of 12 subsequent flight units. The approach with the solar module can be followed in other components of the EPS such as battery and power regulators. Full article
(This article belongs to the Special Issue Verification Approaches for Nano- and Micro-Satellites)
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Open AccessArticle
Engineering Methodology for Student-Driven CubeSats
Aerospace 2019, 6(5), 54; https://doi.org/10.3390/aerospace6050054 - 13 May 2019
Cited by 3
Abstract
CubeSats are widely used by universities and research institutions all over the world. Their popularity is generally attributed to the use of low-cost components, free student labor and simple design. They have been shown to encourage Science, Technology, Engineering and Math (STEM) students [...] Read more.
CubeSats are widely used by universities and research institutions all over the world. Their popularity is generally attributed to the use of low-cost components, free student labor and simple design. They have been shown to encourage Science, Technology, Engineering and Math (STEM) students to become involved in designing, implementing and testing a real functioning spacecraft system. Projects like this encourage students from different disciplines to team up to design and build CubeSats, providing interdisciplinary work experience. Participating students vary in their expertise in developing such systems. Some will work on the project for years while others are not willing to spend two or three consecutive semesters developing a CubeSat project. Despite their simplicity in design and low cost, CubeSats are considered great engineering systems for exploring space. Nevertheless, a large number of CubeSat projects fail due to having an unclear mission, ambiguous system requirements and a lack of documentation. Students need to have a clear vision of how to build a real CubeSat system that can be launched and that can function in space. Thus, this paper proposes engineering methodologies and tools to help students develop CubeSat systems. These tools can help students with planning, collecting, eliciting and documenting the requirements in a well-defined manner. This paper focuses on student-driven CubeSat projects designed by students and faculty members. Additionally, data is presented in this paper to identify the challenges and needs of CubeSat developers. Plans for future work are also discussed. Full article
(This article belongs to the Special Issue Verification Approaches for Nano- and Micro-Satellites)
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Open AccessArticle
A Reliability Engineering Approach for Managing Risks in CubeSats
Aerospace 2018, 5(4), 121; https://doi.org/10.3390/aerospace5040121 - 15 Nov 2018
Cited by 8
Abstract
Besides large-scale space missions, the spread of CubeSats for a variety of applications is increasingly requiring the development of systematic approaches for risk management. Being these applications are based on components with low TRL (Technology Readiness Level) or with limited performance data, it [...] Read more.
Besides large-scale space missions, the spread of CubeSats for a variety of applications is increasingly requiring the development of systematic approaches for risk management. Being these applications are based on components with low TRL (Technology Readiness Level) or with limited performance data, it is required to define approaches which ensure a systematic perspective. This paper aims to present a reliability engineering approach based on FMECA (Failure Mode, Effects, and Criticality Analysis) to manage CubeSat reliability data and prioritize criticalities early in the design phase. The approach firstly proposes an alpha-numeric coding system to support the identification and labeling of failure modes for typical CubeSats’ items. Subsequently, each FMECA coefficient (i.e., Severity, Occurrence, Detectability) has been linked to the CubeSat’s structural properties, reducing subjectivity by means of techno-centric proxy indicators. The approach has been validated in the design phases of a 6-Units university CubeSat for the observation of M-Dwarf stars and binary systems. The performed analysis supported the design process and allowed to identify the major criticalities of the CubeSat design, as demonstrated in the extended case study included in the paper. The formalized method could be applied to design procedures for nano-satellites, as well as being expanded for research and development in a variety of space missions. Full article
(This article belongs to the Special Issue Verification Approaches for Nano- and Micro-Satellites)
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Open AccessArticle
Experimental Validation of an Onboard Transient Luminous Events Observation System for VisionCube via Ground Simulation Environment
Aerospace 2018, 5(4), 100; https://doi.org/10.3390/aerospace5040100 - 21 Sep 2018
Cited by 3
Abstract
The VisionCube is a 2-unit CubeSat developed in house, of which the primary mission is detecting the occurrence of transient luminous events (TLEs) in the upper atmosphere and obtaining corresponding images from a low Earth orbit. An onboard TLE observation system of the [...] Read more.
The VisionCube is a 2-unit CubeSat developed in house, of which the primary mission is detecting the occurrence of transient luminous events (TLEs) in the upper atmosphere and obtaining corresponding images from a low Earth orbit. An onboard TLE observation system of the VisionCube CubeSat is designed and developed by incorporating a photon-sensitive multi-anode photon-multiplier tube (MaPMT) and an image sensor. Also, a distinctive TLE observation software which enables detection of the TLEs and capture of images in a timely manner is devised. By taking into account the limited resources of a small CubeSat in size and power, the onboard observation system is developed employing a system-on-chip device by which both hardware and software can be integrated seamlessly. The purpose of this study is to investigate the functionality of the hardware and the validity of the software algorithm to show that the onboard system will function properly with no human intervention during the operations in space. To this end, a ground simulation facility is constructed to emulate TLEs occurring in space using a set of ultraviolet light-emitting diodes (UV LEDs) inside a darkbox. Based on the analysis of the spectral and temporal properties of the TLEs, the randomly generated UV LED pulses are chosen for verification scenarios for the TLE observation system. The validation results show that the hardware and the software algorithm of the onboard observation systems can effectively detect the TLEs and obtain the images during the in-orbit operation. Full article
(This article belongs to the Special Issue Verification Approaches for Nano- and Micro-Satellites)
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Open AccessArticle
Simulation and Experimental Evaluation of a Flexible Time Triggered Ethernet Architecture Applied in Satellite Nano/Micro Launchers
Aerospace 2018, 5(3), 84; https://doi.org/10.3390/aerospace5030084 - 09 Aug 2018
Cited by 2
Abstract
The success of small satellites has lead to the study of new technologies for the realization of Nano and Micro Launch Vehicle (NMLV) in order to make competitive launch costs. The paper has the objective to define and experimentally investigate the performance of [...] Read more.
The success of small satellites has lead to the study of new technologies for the realization of Nano and Micro Launch Vehicle (NMLV) in order to make competitive launch costs. The paper has the objective to define and experimentally investigate the performance of a communication system for NMLV interconnecting the End Systems as On-Board Computer (OBC), telemetry apparatus, Navigation Unit...we propose a low cost Ethernet-based solution able to provide the devices with high interconnection bandwidth. To guarantee hard delays to the Guide, Navigation and Control applications we propose some architectural changes of the traditional Ethernet network with the introduction of a layer implemented in the End Systems and allow for the lack of any contention on the network links. We show how the proposed solution has comparable performance to the one of TTEthernet standard that is a very expensive solution. An experimental test-bed equipped with Ethernet switches and Hercules boards by Texas Instruments is also provided to prove the feasibility of the proposed solution. Full article
(This article belongs to the Special Issue Verification Approaches for Nano- and Micro-Satellites)
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