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A First-MOVE in Satellite Development at the TU-München
Abstract
MOVE (Munich Orbital Verification Experiment) is a program of the Institute of Astronautics (LRT) at the Technische Universität
München (TUM), which aims on building pico-satellites with university students mainly for educational purposes. First-MOVE
shall create a robust platform as a starting point for sophisticated satellite missions of the institute in the future. In
the paper, the state of development is described, but emphasis is on the requirements for high reliability of the First-MOVE
satellite and how robustness drives the actual design of the satellite.
... Since their introduction in 1999, CubeSats [6] have evolved from purely educational missions to spacecraft with a broad variety of scientific and commercial applications. OOV of critical hardware has been the objective of multiple CubeSat missions in the past [7]–[10] . Thereby, the good costefficiency of CubeSats allows the OOV at an early stage in product development and at a relatively low Technology Readiness Level (TRL) [11]. ...
... Since their introduction in 1999, CubeSats [6] have evolved from purely educational missions to spacecraft with a broad variety of scientific and commercial applications. OOV of critical hardware has been the objective of multiple CubeSat missions in the past [7] [10]. Thereby, the good costefficiency of CubeSats allows the OOV at an early stage in product development and at a relatively low Technology Readiness Level (TRL) [11]. ...
Several promising multi-junction solar cell concepts for space applications are currently under development worldwide. On-Orbit Verification on CubeSats is a cost-efficient method to gain data on critical hardware early in the design validation process. The MOVE-II CubeSat will be used for the verification of novel 4-6 junction solar cells. With a footprint of 10x10 cm², the payload consists of one full size solar cell (8x4 cm²) and up to 7 positions (each 2x2 cm²) for corresponding isotype solar cells. The measurement electronics is based on commercial off-the-shelf hardware. MOVE-II is planned to launch in early 2018 into a 500-550 km sun-synchronous orbit.
... In order to meet these requirements, the hardware and software we develop must allow the reuse of major parts, while at the same time providing the flexibility to replace certain components without major re-design of the overall system. Previous CubeSats at TUM [9,12,14,22] were tailored to the specific needs of the respective mission and cannot provide this flexibility. Thus, a new hardand software ecosystem for CubeSat data handling and control is required for current and future missions at TUM, the LRSM and the newly established Space Missions Laboratory (SML) [15]. ...
At the Laboratory for Rapid Space Missions, we develop CubeSat missions and ISS-based experiments with diverging requirements. Due to limited manpower and resources, we cannot develop new and specifically tailored software and hardware for each of these projects. Instead, we propose the use of a distributed approach with well-defined and statically checked components that can be reconfigured and reused for several missions. The DOSIS framework developed at the Technical University of Munich provides the features required for such a setup. We present the conceptual design of the framework and briefly introduce the first missions using the DOSIS hardware and software setup.
... The CubeSat First-MOVE (depicted in Figure 5) was one of these educational projects [36]. In 2013, I joined a research group developing this satellite at Technical University Munich, Germany, as a master student. ...
Miniaturized satellites enable a variety space missions which were in the past infeasible, impractical or uneconomical with traditionally-designed heavier spacecraft. Especially CubeSats can be launched and manufactured rapidly at low cost from commercial components, even in academic environments. However, due to their low reliability and brief lifetime, they are usually not considered suitable for life- and safety-critical services, complex multi-phased solar-system-exploration missions, and missions with a longer duration.
Commercial electronics are key to satellite miniaturization, but also responsible for their low reliability: Until 2019, there existed no reliable or fault-tolerant computer architectures suitable for very small satellites. To overcome this deficit, a novel on-board-computer architecture is described in this thesis. Robustness is assured without resorting to radiation hardening, but through software measures implemented within a robust-by-design multiprocessor-system-on-chip. This fault-tolerant architecture is component-wise simple and can dynamically adapt to changing performance requirements throughout a mission. It can support graceful aging by exploiting FPGA-reconfiguration and mixed-criticality.
Experimentally, we achieve 1.94W power consumption at 300Mhz with a Xilinx Kintex Ultrascale+ proof-of-concept, which is well within the powerbudget range of current 2U CubeSats. To our knowledge, this is the first COTS-based, reproducible on-board-computer architecture that can offer strong fault coverage even for small CubeSats.
... In 2006 the development of CubeSats at the Technical University of Munich (TUM) began with the first satellite of the Munich Orbital Verification Experiment (MOVE) called First-MOVE [1]. Members of the Institute of Astronautics (LRT) built most parts of this satellite. ...
MOVE-II (Munich Orbital Verification Experiment) is the second satellite of the Technical University of Munich's educational CubeSat program. On December 3, 2018, the satellite was launched on the SSO-A SmallSat Express from the Vandenberg Air Force Base. The following paper shows on-orbit results of the first eight months of operations. It includes analyses based on our own data as well as the open-source ground station network SatNOGS. Lessons learned from mission operations and recommendations for future educational missions are provided. The technical goals of the mission are verifying the satellite's bus and the qualification of a novel type of quadro-junction solar cells. Over 200 students have been developing and testing all components of the satellite since the beginning of the project in April 2015. During the course of the project, the students designed all necessary technology for a CubeSat bus, with the exception of the electrical power system and the on-board computer's hardware. Furthermore, the students developed ground station software as well as an operations interface from scratch. The technological achievements of the mission range from a linux-based onboard computer software over a magnetorquer-based attitude determination and control system to two novel transceivers for UHF/VHF and S-Band. A reusable mechanism, based on shape-memory-alloys, deployed the four solar panels, providing the necessary power. Only hours after the deployment, we received the first signals of the satellite. The commissioning of the ground station and the effects of an insufficient power budget of the tumbling satellite preoccupied us during the first month, as well as frequent watchdog resets. During the commissioning of the Attitude Determination and Control System (ADCS), a spin rate of 200 °/s was observed, although the actuators were not activated yet. Detailed analysis with the help of recordings provided by our own ground station as well as the SatNOGS ground station network revealed a slow increase of the spin rate since the launch. In the following weeks the spin rate further increased to over 500 °/s. Afterwards we were able to modify our ADCS actuation in a way to reduce the spin rate again. Currently MOVE-II is detumbled and we are moving towards regular scientific operation. After a presentation of the results, lessons learned from our mission operations are discussed. The paper discusses the measured values and analyzes the reasons for the observed behaviour. Also the changes made on MOVE-IIb, a slightly improved copy of MOVE-II, will be explained. The paper concludes with recommendations for designers of upcoming educational satellite missions, especially regarding resilience against negative power budgets.
... The MOVE-II satellite is a single-unit (1U) CubeSat currently under development at the Technical University of Munich (TUM). The MOVE (Munich Orbital Verification Experiment) satellite program was initiated in 2006 with the objective of building a single-unit CubeSat verification platform called First-MOVE (Czech et al., 2010). First-MOVE was launched in late 2013 and operated in space for about a month. ...
... Initiated in 2006, the MOVE CubeSat Program of TUM has run with the main goal of hands-on education of undergraduate and graduate students since then. The program's first satellite, First-MOVE, was launched in late 2013 and operated in space for a month [1]. Funded by the German Aerospace Center (DLR) as an educational project, the goal of MOVE-II [2] is to build and operate a 1U-Cubesat capable of supporting a scientific payload, evolving the subsystems that were developed in-house for First-MOVE and applying the lessons learned [3] from the project. ...
Changes due to design flaws impose major costs, delays and high risks on any spaceflight project. The later the change, the riskier and more expensive it is. System changes due to failures detected during spacecraft assembly are usually one of the last hardware flaws to be found and therefore impose major risks on the overall project. Traditionally, this is overcome by metal or wooden mock-ups early in the process. However, to respond to design changes in a fast manner and to properly explore the remaining options by building multiple full size mock-ups in a short time interval, rapid prototyping was used by the authors. This paper provides lessons learned of the Munich Orbital Verification Experiment II (MOVE-II), related to rapid prototyping technologies used during the development phase. MOVE-II is the second CubeSat mission of the Chair of Astronautics at the Technical University of Munich (TUM). Early in the design process, a 3D printed structural model of the CubeSat was built to verify the CAD model, the assembly strategy, and to track down potential system level design deficiencies. By doing so, minor and major flaws concerning integration of the satellite were found in an early project phase. Furthermore, multiple design alternatives were 3D printed during the development process, not only exploring different solutions but also defining cable paths and cable lengths and evaluating the corresponding assembly process. In difference to traditional methods, 3D printing allows for a shorter implementation time span of different design options. In addition it was possible to conduct dress-rehearsals of the integration procedure early on in order to save time in later project phases, and without potentially harming expensive hardware. Due to the early integration of the prototype, Ground Support Equipment (GSE) and specific tools could be defined ahead of time. The biggest non-technical benefit was, that the physical model simplified communication of problems and possible configurations as well as introductions to the system. Display material was always available for the developing team, either for presentations of the project or for recruitment of new team members. The paper concludes with a brief assessment of the limitations of rapid prototyping technologies for risk reduction and process acceleration. Assessment of mechanical functionality as well as mechanical fits are limited due to production tolerances. Therefore the deployment mechanism of MOVE-II could not be tested sufficiently. Finally, future improvements are shown for upcoming CubeSat missions of the TUM.
... The project is a cooperation between the Institute of Astronautics (LRT) and the astronautical student research group Wissenschaftliche Arbeitsgemeinschaft für Raketentechnik und Raumfahrt (WARR) of TUM. The goal of the MOVE-II mission is to test, verify and qualify a new satellite bus for future mission with demanding scientific payloads, evolving the subsystems that were developed in-house for TUM's first CubeSat First-MOVE 4 and applying the lessons learned 5 from that project. As payload of MOVE-II, the performance and degradation of novel solar cells in outer space shall be investigated. ...
MOVE-II (Munich Orbital Verification Experiment) will be the first CubeSat of the Technical University of Munich (TUM) utilizing a magnetorquer-based active attitude determination and control system (ADCS). The ADCS consists of six circuit boards (five satellite side panels and one central circuit board in satellite stack), each equipped with a microcontroller, sensors and an integrated coil. The design enables redundancy and therefore forms a fault-tolerant system with respect to sensors and actuators. The paper describes the hardware implementation, algorithms, software architecture, and first test results of the integrated ADCS on the engineering unit. A possibility to upgrade and extend our software after launch will enable further research on new and innovative attitude determination and control strategies and distributed computation on satellites. The MOVE-II flight unit is in the integration and test phase with an intended launch date in early 2018.
... Such extremely simple systems are insufficient for more advanced missions with higher compute power, reliability, data storage and lifetime requirements, especially such with scientific or commercial objectives. First-MOVE [4], the first nanosatellite constructed by students at Technical University Munich (TUM), followed this principle of extreme simplicity, however even such a comparably straight forward OBC design became a challenge to implement. ...
... In 2006, the CubeSat program MOVE (Munich Orbital Verification Experiment) was initiated at the Institute of Astronautics (LRT) at the Technische Universität München (TUM), Germany. Apart from the ambition of designing and building a single-unit CubeSat verification platform, called First-MOVE [1], the hands-on education of undergraduate and graduate students has been the main goal of the program since then. When First-MOVE launched in late 2013, a total of more than 70 students from different disciplines had participated successfully in the project. ...
This paper presents the on-orbit results and the lessons learned from First-MOVE (Munich Orbital Verification Experiment), the first CubeSat mission of the Institute of Astronautics (LRT) at the Technische Universität München (TUM). The development of the satellite started as a student project in 2006. First-MOVE was launched on November 21st 2013. The student-designed and built satellite was operated for almost a month. On December 19th 2013 a major malfunction occurred, presumably due to an anomaly in the on-board data handling system (OBDH), which left the satellite in a mode where it is only transmitting continuous wave (CW) beacons. Although the short mission duration prevented several mission objectives from being achieved, the overall program can be considered a success, as it permitted more than 70 students hands-on experience and led to major in-house technology and spaceflight processing developments. The main aspects of a university-led satellite development, the results of the mission and both technical as well as educational lessons learned are described, including the management and planning of student projects as well as motivational and system engineering aspects. These aspects include planning the project around student's schedules rather than in a traditional, linear fashion, the careful selection and distribution of team members to subsystem teams and the deviation from traditional systems engineering process flows in order to retain student motivation. The importance of large milestone reviews and kick-off events as short term goals and as a means to recruit new team members are highlighted. Academic outreach programs included a one week summer school held in 2011 to recruit and train new students in a time-efficient setting in relevant technical aspects. The paper explains in more detail the technical lessons learned from the major satellite subsystems, both self-developed and purchased. The self-developed systems include, among others, the design of the solar-panel release mechanism, the unique CMOS latch-up protection system, the hard-command unit and the OBDH system. Although we can report a flawless function of all the purchased subsystems in-orbit, the detailed in-house system-level testing of these components is a major lessons learned of First-MOVE from the prospective of student education and system knowledge. Despite the existence of documentation, the time and knowledge needed for designing a test bed for the electric power system (EPS) and the subsequent testing was underestimated. Furthermore, from a testing prospective, the importance of integrated system-level testing and the need for longer, continuous operations test of the satellite are emphasized. On-orbit flight data, as well as educational lessons learned for efficient student involvement during mission operations are highlighted. An outlook to MOVE II, the follow-up satellite project of LRT, outlines how the lessons learned of the last generation students can be carried over and how they will influence future (student) satellite developments and spaceflight development processes at LRT.
... Current and past CubeSat missions are based on self-developed [2] or commercial off-the-shelf (COTS) [3], [4] deployable and/or expandable structures for solar power generation. Most of the mechanisms used for solar panel deployment rely on conventional techniques like the utilization of melting wires and springs for hold down and release. ...
This paper investigates the utilization of deployable and expandable structures for communication purposes and solar power generation on CubeSats. We present the design and on-orbit results of the flight-proven solar-panel release mechanism of the first satellite of Technische Universität München First-MOVE, as well as the preliminary design of a solar panel deployment mechanism based on smart memory alloys for the second satellite MOVE II. Preliminary studies on a CFRS (carbon fibre reinforced silicone) shell membrane antenna as well as two other possible payloads for MOVE II are briefly described.
... A picosatellite verification platform called MOVE (Munich Orbital Verification Experiment), which is based on the CubeSat standard, is being developed at the Institute of Astronautics at the Technische Universität München [1]. MOVE shall be a low-cost verification possibility for MEMS (Micro Electro Mechanical System) technology, helping to bridge the so-called "Valley of Death" which prevented operational aerospace application of such new technologies often in the last years. ...
On October 22nd 2008, the VERTICAL (VERification and Test of the Initiation of CubeSats After Launch) experiment was flown
on the REXUS 4 sounding rocket mission at Esrange in Kiruna, Sweden. The experiment’s objective was to verify critical hardware
to be used on the MOVE CubeSat in a space environment. The items to be verified were multiple micro switches from different manufacturers and a solar panel deployment mechanism developed at TUM. The deployment mechanism is triggered by a melt wire. During launch, the switches are depressed by a plate
which is retracted once the rocket is near its apogee. This simulates the satellite’s ejection from the launch vehicle. The
verification sequence was executed as planned during the 10-min flight and the experiment was safely recovered. The acquired
data suggests that the deployment mechanism can be used as is and COTS of verified quality micro switches will survive LEOP
conditions and are suitable for further testing, addressing their long-term reliability.
MOVE-II (Munich Orbital Verification Experiment II) is a 1 Unit CubeSat currently under development at the Technical University of Munich (TUM). This paper reports on the technical as well as the organizational advancements of the project. With overall more than 130 students involved so far, the project is currently in Phase D, with the launch of the satellite scheduled for early 2018. For communication purposes, MOVE-II will utilize a novel robust and efficient radio protocol for small satellite radio links, called Nanolink, both on an UHF/VHF transceiver and an S-Band transceiver. The usual power restrictions of the 1U envelope are overcome by four deployable solar panels, which are held down and released by a reusable shape memory mechanism. This allows repeated tests of the mechanism and true test-as-your-fly philosophy. As its scientific goal, the MOVE-II CubeSat will be used for the verification of novel 4-junction solar cells. With a footprint of 10x10 cm, the payload consists of one full size solar cell (8x4 cm) and five positions (each 2x2 cm) for the corresponding isotype solar cells. As opposed to its predecessor mission, MOVE-II will be the first CubeSat of TUM utilizing a magnetorquer based, active attitude determination and control system (ADCS). The system consists of five Printed-Circuit-Boards with directly integrated magnetic coils, forming the outer shell of the spacecraft, and one so-called ADCS Mainboard, located in the board stack of the satellite. Each Sidepanel has its own microcontroller and is connected to the ADCS Mainboard with one of two redundant SPI buses. From an organizational point of view, we tried to increase the reliability of MOVE-II by fast prototyping and releases as well as enhanced hardware-in-the loop tests. We will present the application of agile software development in the project as well as methods that we applied to assure reliability on system level. For that purpose a Reliability Growth Model, based on our CubeSat Failure Database, was adapted for the project.
This paper presents the fundamental work on the attitude control design using solely magnetic actuation for the MOVE-II mission. Two control modes are primarily considered: detumbling and sun pointing control. Regarding the sun pointing control, two approaches are discussed. The first is the Spin Stabilized Sun Pointing Control (SSPC) which provides gyroscopic stiffness against disturbances. The second is a non-spinning approach called Reduced Sun Pointing Control (RSPC). Simulation results have shown satisfactory performance providing proof of concept and motivation for further work.
On October 22nd 2008, the VERTICAL (VERification and Test of the Initiation of CubeSats After Launch) experiment was flown
on the REXUS 4 sounding rocket mission at Esrange in Kiruna, Sweden. The experiment’s objective was to verify critical hardware
to be used on the MOVE CubeSat in a space environment. The items to be verified were multiple micro switches from different manufacturers and a solar panel deployment mechanism developed at TUM. The deployment mechanism is triggered by a melt wire. During launch, the switches are depressed by a plate
which is retracted once the rocket is near its apogee. This simulates the satellite’s ejection from the launch vehicle. The
verification sequence was executed as planned during the 10-min flight and the experiment was safely recovered. The acquired
data suggests that the deployment mechanism can be used as is and COTS of verified quality micro switches will survive LEOP
conditions and are suitable for further testing, addressing their long-term reliability.