1,721,105 research outputs found
The Radiation Environment and effects analysis of the LUMIO Mission
Full text linkThe 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.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Space Systems Egineerin
Modular impulsive green monopropellant propulsion system (Mimps-g): For cubesats in leo and to the moon
No full textGreen propellants are currently considered as enabling technology that is revolutionizing the development of high-performance space propulsion, especially for small-sized spacecraft. Modern space missions, either in LEO or interplanetary, require relatively high-thrust and impulsive capabilities to provide better control on the spacecraft, and to overcome the growing challenges, particularly related to overcrowded LEOs, and to modern space application orbital maneuver requirements. Green monopropellants are gaining momentum in the design and development of small and modular liquid propulsion systems, especially for CubeSats, due to their favorable thermophysical properties and relatively high performance when compared to gaseous propellants, and perhaps simpler management when compared to bipropellants. Accordingly, a novel high-thrust modular impulsive green monopropellant propulsion system with a micro electric pump feed cycle is proposed. MIMPS-G500mN is designed to be capable of delivering 0.5 N thrust and offers theoretical total impulse ITot from 850 to 1350 N s per 1U and >3000 N s per 2U depending on the burnt monopropellant, which makes it a candidate for various LEO satellites as well as future Moon missions. Green monopropellant ASCENT (formerly AF-M315E), as well as HAN and ADN-based alternatives (i.e., HNP225 and LMP-103S) were proposed in the preliminary design and system analysis. The article will present state-of-the-art green monopropellants in the (EIL) Energetic Ionic Liquid class and a trade-off study for proposed propellants. System analysis and design of MIMPS-G500mN will be discussed in detail, and the article will conclude with a market survey on small satellites green monopropellant propulsion systems and commercial off-the-shelf thrusters.</p
Input-State Feedback Linearization of a Boost DC/DC Converter
No full textThe paper presents a procedure to achieve an input-state feedback linearization on a bidirectional Boost DC/DC converter connected to a passive load. The system linearization is achieved by a proper state-space/output transformation performed on a non-dimensional form of the analytical model. The resulting system is then controlled through a standard linear regulator. An online load estimation technique is also provided to overcome the transformations parameter dependency. The proposed approach has been numerically tested and compared with a standard two-loop controller
Dual Chemical-Electric Propulsion Systems Design for Interplanetary CubeSats
No full textInterplanetary CubeSats enable universities and smallspacecraft- consortia to pursue low-cost, high-risk and highgain Solar System Exploration missions, especially Mars; for which cost-effective, reliable, and flexible space systems need to be developed. Missions to Mars can be achieved through a) in-situ deployment by a mothership and b) highly flexible stand-alone CubeSats on deep-space cruise. The current work focuses on sizing and establishing critical design parameters for dual chemical-electric propulsion systems that shall enable a stand-alone 16U CubeSat mission on a hybrid high-thrust & low-thrust trajectory. High thrust is used to escape Earth whereas low-thrust is used in autonomous deep-space cruise, achieving ballistic capture, and emplacement on an areosynchronous orbit at Mars. Chemical propulsion characterisation is based on V requirement and a heuristic optimisation of thrust, specific impulse and burn time while balancing transfer time and propellant mass. Limitations are set to minimise destabilising momentum. Electric propulsion characterisation is based on the V, power consumption, and trajectory requirements for fueloptimal and time-optimal strategies. The sizes amount to 16% and 21% of the assumed total mass ( 30 kg) for chemical and electric systems, respectively.Space Systems Egineerin
Designing the Radio Link for a Lunar CubeSat: the LUMIO Case
Full text linkThe Lunar Meteoroid Impact Observer (LUMIO) is a mission designed to observe, quantify, and characterize the meteoroid impacts by detecting their flashes on the lunar far side. Earth-based lunar observations are restricted by weather, geometric and illumination conditions, while a lunar orbiter can improve the detection rate of lunar meteoroid impact flashes, as it would allow for longer monitoring periods. This paper will focus on the communications and radio navigation system of the mission, designed for the ESA roadmap for lunar exploration. LUMIO has been designed to operate autonomously after deployment from a lunar mother spacecraft in a low inclination lunar orbit and to reach without human intervention his final destination orbit close to the Earth-Moon L2 point, where science can be carried out. Being the destination orbit always in view from Earth (despite a distance of 460000 - 480000 km), Direct-to-Earth communication was added to the mission as a mean to reduce risk and allow independent verification of several of the innovative technologies that would be demonstrated, first of all autonomous navigation. A detailed link budget analysis will be presented for all mission phases for both the link with the mother spacecraft in low lunar orbit and the link with Earth. Beside defining the achievable data transfer, we will focus also on evaluating the available ground stations to better evaluate mission cost with respect to science return. Radio-navigation performances will also be evaluated to estimate the position and relative velocity accuracy, given also the limited performances available for the on-board navigation transponder. This will help also better defining the on-board autonomous navigation system, constraining the total error budget. Further strategies, such as beacon tones, will be evaluated to lower the overall operational cost by employing continuous monitoring with a low performances ground station and, only when needed, perform high speed downlink using a deep-space class ground station. This strategy is considered of extreme importance, especially for small missions, to allow opportunistic operations on high gain antennas, given their very busy schedule. Keywords: LUMIO, CubeSat, Lunar, Radio, linkGreen Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Space Systems Egineerin
Selection of the Propulsion System for the LUMIO Mission: an Intricate Trade-Off Between Cost, Reliability and Performance
Full text linkThe Lunar Meteoroid Impact Observer (LUMIO), one of the two winning concepts of the SysNova Lunar CubeSats for Exploration call by ESA, is a mission designed to observe, quantify, and characterize the meteoroid impacts on the Lunar far side by detecting the flashes generated by the impact. 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 mission, which has successfully completed its Phase A in March 2021, 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 background noise due to the Earth. The propulsion system is one of the most crucial design choices for the LUMIO spacecraft. It accomplishes various functions: orbital transfer from the initial Lunar orbit to the final halo orbit around L2, station keeping, reaction wheel desaturation, end of life disposal manoeuvres. The total required Delta-V budget for orbital transfer and station keeping is 201.8 m/s, plus an additional total impulse for reaction control tasks ranging from 110 Ns to 170 Ns, depending on the type of reaction control system that is selected. This paper presents a detailed summary of the phase A selection and design of the LUMIO propulsion system, based on the full list of requirements generated by the mission analysis. The main challenges of this process and the way they have been tackled are presented and discussed, including: use of two separate systems as opposed to an integrate one for main propulsion and reaction control tasks; availability of sufficiently reliable European propulsion options, to reduce the general mission costs; feasibility of replacing a chemical/cold gas system with electric propulsion; possible need for custom changes to the design of the selected COTS option (e.g. due to tank sizing).Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Space Systems Egineerin
A hybrid modulation technique for the dc-bus voltage balancing in a three-phase npc converter
Full text linkIn this paper a new pulse width modulation technique for three-phase neutral point clamped (NPC) converter is presented, with the aim to actively control the dc-bus capacitors' voltages. To meet this requirement, usually NPC modulation techniques are either based on the sole common mode voltage injection (CM1) or on the sole multi-step (MS) switching mode of operation. Contrarily, the presented approach combines these two strategies, taking advantages of all their main benefits while keeping the switching transitions to the minimum required number. The approach has been numerically tested and compared with some of the other strategies, showing an overall better behaviour, especially for high modulation indices
Power Control Strategy of a Delta-Connected Photovoltaic Cascaded H-Bridge Converter for Low Voltage Distribution Networks in Energy Community
No full textThe paper deals with the power control of a delta connected Cascaded H-Bridge (CHB) converter equipped with photovoltaic (PV) modules. A hierarchical architecture of energy management is proposed: A 'Module level' controller performs a Maximum Power Point Tracking (MPPT) algorithm to achieve the optimal utilization of each PV module; a 'Leg level' controller manages the power flow control within the modules of a single CHB phase leg, and a 'System' level controller manages the active power flow between the three CHB phases and the reactive power generation towards the grid. The active power control is aimed at the compensation of the mismatches between the different PV-powered modules, which may come from partial shadowing phenomena. A power unbalance compensation between cascaded modules is implemented through the Pulse Width Modulation (PWM) algorithm, while the unbalance compensation between the phases is implemented through the phase currents control. To compensate the active power unbalance due to PV module mismatches, the obtained effect is equivalent to the injection of a zero sequence current. A reactive power control has been implemented to perform a power factor (PF) correction, too. A set of numerical simulations validate the effectiveness of the algorithm, which can simultaneously achieve the desired active power generation from all the PV panels and the desired PF control towards the grid
Assessment of the Propulsive Performance of Fuel Vapor Pressurized Hydrogen Peroxide-Ethane Rocket Engines
Full text linkIn the last years low-toxicity “green” storable liquid propellants have become considerably more attractive as possible substitutes for nitrogen oxides and hydrazines. The main advantage of “green” propellants is represented by the significant cost savings associated with the drastic simplification of the health and safety protection procedures necessary during propellant production, storage and handling. Fuel Vapor Pressurization (FVP) technology of “green” bipropellant rocket engines potentially offers very significant additional advantages in terms of system cost, complexity, reliability, safety and mass, with practically no penalty in propulsive performance compared to traditional storable propellants such as mixed nitrogen oxides and hydrazines. Pioneering FVP experiments were carried out by Goddard, Wyld and others. Detailed studies have been conducted and several tests have been successfully performed since 1994 in the US, but no such experience is presently available in Europe, nor FVP has ever attained flight readiness anywhere in the world. The main characteristics of the FVP system examined in this work consist in the use of storable, non-toxic, inexpensive, non hypergolic, high-energy propellants such as hydrogen peroxide (HP, H2O2) and ethane (C2H6) and in the storage of these propellants in a single lightweight tank, using a flexible diaphragm or a bladder to separate the fuel from the oxidizer and a catalytic reactor to decompose the hydrogen peroxide before mixing and combustion with ethane. This configuration therefore yields a very simple and yet highly efficient and reliable propulsion system by eliminating the cost, the weight and complexity of propellant tanks and pressurization bottles, pressure and flow regulators and ignition systems. These advantages are of special relevance in low- or mediumthrust rocket engines for the rapidly expanding market of “small” space missions and led the authors to focus on the analysis and assessment of propulsion systems operating according to this concept. The present paper reports therefore the preliminary evaluation of fuel vapor pressurized H2O2-C2H6 rocket propulsion systems. The results of the analysis confirm that the development of FVP technology may represent a significant contribution to the containment of the propulsion cost of small- and medium-size spacecrafts
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