Attitude control of a flexible triangular truss in space

The capabilities of maximising standard payload modules’ functionalities for applications such as on-orbit satellite servicing or planetary exploration depend critically on the creation and availability of a standard interface (IF). Standard interface should provide, aside from the necessary mechanical interconnections, electrical power and data connections, as well as thermal transfer between “building block” payload modules. The overall flexibility enabled by such IF will allow endless reconfigurations of payload and other modules for different functional requirements. This can be considered a game changer technology, enabling transformation from the current approach to space missions, deploying single-use system with pre-planned and limited functionalities, to a radically new approach with multi-use, dynamically reconfigurable and multi-functional systems. Hence, SIROM aims to set a new research agenda for future affordable space missions. Within this context, the partners of the SIROM (Standard Interface for Robotic Manipulation of payloads in future space missions) project are developing the first standard IF solution that combines the four required functionalities in an integrated and compact form for future space missions. With a mass lower than 1.5 kg and having an external diameter of 120 mm and a height of 30 mm, this novel interface permits not only mechanical coupling but also electrical, data and thermal connectivity between so called Active Payload Modules (APMs), as well as other modules such as the robotic end-effectors. This multi-functional IF features an androgynous design to allow for replacement and reconfiguration of the individual modules in any combination desired. It consists of the following sub-assemblies: mechanical IF, electrical IF, data IF, thermal IF and IF controller. A clear advantage of SIROM design is that its mechanical IF consists of a latching and guiding systems for misalignment correction, capable of withstanding certain robotic arm positioning inaccuracies: ± 5 mm translation and ± 1.5° rotation in all axes. Regarding the electrical and data IFs, SIROM transfers up to 150 W electrical power and provides a data transfer rate of 100 Mbit/s via SpaceWire, plus command communication with speeds up to 1Mbit/s via CAN bus. The thermal IF provides fluidic ports for flow transfer and has the potential to transfer 2500 W between APMs accordingly provided with the corresponding close-loop heat exchange system. Although not envisaged for SIROM current design, a possible variation could be to use these ports for satellite re-fuelling. Apart from that, SIROM exhibits redundant coupling capabilities: it can match and couple another completely passive SIROM. It is provided with main and redundant connectors for thermal, electrical, data and control flow in case of one of the lines fails. All in all, SIROM will enable long duration missions with no logistic support, refurbishing, maintenance and reconfiguration of satellites, cost efficiency and simplification of the tool exchange in scientific exploration missions. SIROM is designed to be a common building block for European and possibly world future space robotics enabled missions.

Material Efficiency and Energy Use

The present research investigates the potential for reducing the environmental impacts of structural systems through a more efficient use of materials. The main objective of this research is to explore and to develop a holistic and integrated methodology that utilises Building Information Modelling's (BIM) capabilities combined with structural analysis and Life Cycle Assessment (LCA) as well as a two-staged structural optimisation solver that achieves efficient and environmentally responsible steel design solutions. The implemented workflow utilises Autodesk Revit-BIM, Tally-LCA and Autodesk Robot-Structural Analysis. RobOpt is the plug-in that has been established using the Application Programming Interface (API) of Robot and the .NET framework of C?, and it inherits several structural functionalities based on Robot Finite Element Method (FEM) engine. The proposed RobOpt application can be accessed via a graphic user interface (GUI) within the Robot software. The developed BIM-enabled optimisation methodology could be utilised as a design tool to inform early stage structural design solutions. A prototypical steel framed structural system under certain loads has been explored. The resulting bespoke I-beam sections from the custom genetic algorithm (GA) optimisation demonstrate that significant savings-up to 21%-can be achieved in all tested environmental indicators when compared to the standard UK catalogue of steel sections. Considering all, the proposed framework constitutes a useful and an intuitive workflow, which aims to quantify the environmental savings of structural systems by utilising, advanced computational analysis and common construction techniques.

The global climate crisis forces the search for new ecological sources of energy and mining methods. Space mining can solve those problems, but, first, wide geological surveying space missions using drilling methods are necessary. Additionally, drilling methods will be important in geological, life searching, geoengineering, and many other studies of extraterrestrial objects. Space is becoming a new area of possible drilling applications. Designing future space drilling missions requires adapting drilling technologies, not only to the conditions of the space environment, but also to the economic and technological realities of the space industry. The possibility of constructing low mass coring devices with energy consumption below 100 W was investigated in this paper. Minimization of energy consumption and mass of a coring is essential for the device to be used in space missions, when lander instruments supplied by low power electric battery are expected to work reliably and the launch cost (depending of mass) at an economically acceptable level. Some similar devices investigated for the future space missions are known from papers listed in the references. To answer whether or not it is possible to build such devices, the authors performed initial drillability tests. The obtained results are presented in this paper.

Human exploration of space contains many ethical challenges. Future long-term space missions will generate specific problems and place new demands on humanity. One of them is the concept of human enhancement, primarily through gene editing, for the implementation of long-term space missions. This book hypothesizes that large-scale application of human enhancement may be necessary to enable space exploration and exploitation. The book discusses the many arguments for and against human genetic modification for space missions. It also considers the most controversial type of modification, germline gene editing, and presents many arguments in favor of applying even radical and considered controversial forms of human enhancements today. The book shows that the environment of future space missions is a unique and different ethical environment from Earth’s and requires a modified bioethical approach. The bioethics of space missions should be syncretic, issue-driven, and highly dependent on the purpose of space missions. The book points out the importance of discussing future scenarios of human development. Space bioethics is presented as part of futures studies. The book considers futures of humanity in space that are possible, probable, preferable, but also dystopian. The aim of these considerations is to prevent the development of these worst-case scenarios. The book suggests that we should look to the development of biomedicine with greater optimism and hope. Human enhancement via gene editing for space missions is presented as a pragmatic tool rooted in the principle of well-being.

In modern aerospace technology, strapdown inertial navigation systems (SINS) are widely used, using fiber-optic (FOG) or ring laser (CLG) gyroscopes. During the operation of such systems, the sensitivity axes are rotated relative to the basic coordinate system. The resulting angles between the axes of the base coordinate system and the axes of sensitivity of the navigation system (non-orthogonality) are one of the factors leading to an increase in the measurement errors of the device, which affects the measurement accuracy. During operation, the system is affected by vibrations of various nature, the impact of which can contribute to the appearance of non-orthogonality. The purpose of this work is to determine the maximum permissible vibration amplitudes affecting the SINS body according to the permissible values ​​of the deviation of the FOG sensitivity axes for two variants of the SINS layout. An approach to determining the permissible amplitudes of an external harmonic impact on the unit of a strapdown inertial navigation system based on fiber-optic or ring laser gyroscopes is considered. A design scheme, mathematical and finite element models for calculating natural frequencies and forced oscillations of a strapdown inertial navigation system unit have been developed. In various frequency ranges, numerical calculations have determined the boundary values ​​of the amplitudes of the external harmonic impact on the base of specific configurations of the SINS assembly. It has been established that dangerous states take place in the region of the 1st natural frequency of the system, as well as near higher frequencies. Comparison of the results for design options 1 and 2 allows us to conclude that in order to weaken the effect of vibrations on the accuracy of the SINS unit, it is advisable that the lowest natural vibration frequencies for the SINS assembly be as high as possible (more than 1000 Hz).
 Key words: vibration; fiber optic gyroscope; strapdown inertial navigation system; finite element method; natural frequencies and modes of vibration.

The transition from regular to chaotic motions in deterministic flows is characterized by a change from a discrete Fourier spectrum to a broadband one. The onset of chaos is thus associated with the creation of an infinite number of new Fourier modes. Given a system that generates a time series $x(t),$ we study the transition to chaos from the perspective of analytic signals, which are defined via the Hilbert transform. In order to identify distinct analytic signals, we decompose the original time series $x(t)$ into a finite number of modes that correspond to proper rotations in the complex plane of their analytic signals. We provide numerical evidence that at the transition, there is no substantial change in the number of analytic signals characterizing $x(t).$ Furthermore, the distributions of the instantaneous frequencies of the analytic signals in the chaotic regime are well localized and exhibit no broadband feature. These results suggest a simple organization of chaos in terms of analytic signals.

Modal noise appears due to the non-uniform and unstable distribution of light intensity among the finite number of modes in multimode fibres. It is an important limiting factor in measuring radial velocity precisely by fibre-fed high-resolution spectrographs. The problem can become particularly severe as the fibre’s core become smaller and the number of modes that can propagate reduces. Thus, mitigating modal noise in relatively small core fibres still remains a challenge. We present here a novel technique to suppress modal noise. Two movable mirrors in the form of a galvanometer re-image the mode-pattern of an input fibre to an output fibre. The mixing of modes coupled to the output fibre can be controlled by the movement of mirrors applying two sinusoidal signals through a voltage generator. We test the technique for four multimode circular fibres: 10 and 50 $\mu$m step-index, 50 $\mu$m graded-index, and a combination of 50 $\mu$m graded-index and 5:1 tapered fibres (GI50t). We present the results of mode suppression both in terms of the direct image of the output fibre and spectrum of white light obtained with the high-resolution spectrograph. We found that the galvanometer mitigated modal noise in all the tested fibres, but was most useful for smaller core fibres. However, there is a trade-off between the modal noise reduction and light-loss. The GI50t provides the best result with about 60 per cent mitigation of modal noise at a cost of about 5 per cent output light-loss. Our solution is easy to use and can be implemented in fibre-fed spectrographs.

When the heat released by a flame is sufficiently in phase with the acoustic pressure, a self-excited thermoacoustic oscillation can arise. These nonlinear oscillations are one of the biggest challenges faced in the design of safe and reliable gas turbines and rocket motors. In the worst-case scenario, uncontrolled thermoacoustic oscillations can shake an engine apart. Reduced-order thermoacoustic models, which are nonlinear and time-delayed, can only qualitatively predict thermoacoustic oscillations. To make reduced-order models quantitatively predictive, we develop a data assimilation framework for state estimation. We numerically estimate the most likely nonlinear state of a Galerkin-discretized time delayed model of a horizontal Rijke tube, which is a prototypical combustor. Data assimilation is an optimal blending of observations with previous state estimates (background) to produce optimal initial conditions. A cost functional is defined to measure the statistical distance between the model output and the measurements from experiments; and the distance between the initial conditions and the background knowledge. Its minimum corresponds to the optimal state, which is computed by Lagrangian optimization with the aid of adjoint equations. We study the influence of the number of Galerkin modes, which are the natural acoustic modes of the duct, with which the model is discretized. We show that decomposing the measured pressure signal in a finite number of modes is an effective way to enhance state estimation, especially when nonlinear modal interactions occur during the assimilation window. This work represents the first application of data assimilation to nonlinear thermoacoustics, which opens up new possibilities for real-time calibration of reduced-order models with experimental measurements.

Natural frequencies of square plates with reinforced central holes subjected to inplane loads

The development of Map Assessments, especially in analog space missions, plays a fundamental role in identifying, assessing, and mitigating potential threats and challenges that may arise during space operations in extraterrestrial environments. These missions are designed to simulate real space flight conditions, allowing space agencies and exploration teams to test and refine procedures, technologies, and protocols before implementing them in actual space missions. During the risk analysis, various factors are considered, including: i) Environmental Risks: the context in which the mission will occur, as extreme weather conditions; ii) Health and Safety Risks: health and safety of the team members, as exposure to radiation; iii) Operational Risks: associated with operational procedures, communications, resource management, team coordination, and decision-making during the mission; iv) Psychosocial Risks: interpersonal conflicts, and emotion management along with the crew. Based on the analysis of these risks, strategies and mitigation measures are developed to minimize the likelihood of adverse events and their potential consequences. This study aims to analyze occupation risks, divided into physical, chemical, ergonomic, biological, and mechanical, at the analog space station Habitat Marte, located in Rio Grande do Norte, Brazil. As a result, various sources of danger and vulnerabilities in analog space operations were identified, which include: a. identification of the biological risk group, which includes symptoms associated with transmitted diseases or infections, the possibilities of contamination and spread of transmissible diseases; b. identification of the chemical risk group, which includes the presence of harmful gases, such as carbon dioxide and methane, symptoms of exposure, such as breathing difficulties; c. Identification of the mechanical risk group, where insect bites, possible fires, structural collapses, d. Identification of the physical risk group, which includes exposure to extreme temperatures, dehydration, fatigue and falls, e. Identification of the ergonomic risk group, strongly present in issues such as work in confined spaces and repetitive movements, f. Identification of the psychological risk group, which ultimately encompasses stress due to confinement, lack of rest, and fear of incidents during the journey. By conducting this comprehensive and multidisciplinary risk analysis, space agencies and exploration teams can significantly increase the safety, efficacy, and success of their future missions in space. These results provide a solid foundation for the continuous development of risk management strategies and safety measures for long-duration space missions, contributing to the viability and success of future human expeditions to Mars and beyond.

The mode characteristics and the parameter sensitivity for a two-stage NGW spur planetary gear system are studied based on the principles of structure natural dynamical characteristics. Considering the influence of flexible structure including shaft, the planet carrier, and the ring-gear, the coupled lateral-torsional-axial vibration dynamical model of the planetary gear system is established under the generalized coordinate system using the shafting element method. With the model, the natural frequency and vibration mode are solved, and the results indicate that the flexibility of ring-gear has a greater effect on natural frequency. Several distinct types of vibration mode are summarized, such as planet torsional mode, sun-gear shaft axial mode, ring-gear axial mode and so on. However, the translational mode which is one of the modes in the coupled lateral-torsional lumped mass model is not found in this study. Within the scope of the time-varying, mesh stiffness mainly affects the planet torsional mode of corresponding stage. Furthermore, the variation of radial bearing stiffness will also do effect on axial vibration mode, and the variation of bearing stiffness not only affects the vibration modes of adjacent stage of planetary gear train, but also affects the nonadjacent stage. The results demonstrate the coupling characteristics of the system under the free vibration condition.

The results of studying thin-walled plates and cylindrical shells interacting with the stationary or flowing viscous compressible fluid are presented. The numerical solution of the problem has been carried out using the finite element method. The motion of liquid medium is described by the system of linearized Navier-Stokes equations, the solution of which is sought for in the form of the acoustic approximation in terms of velocity perturbation potential. The relations obtained for liquid and the corresponding boundary conditions are transformed by the Bubnov-Galerkin method. The behavior of a thin-walled structure is described in the framework of the classical theory of thin plates. The mathematical formulation of the dynamic problem of an elastic body is based on the variational principle of virtual displacements. Stability estimation is based on the calculation and analysis of complex eigenvalues of a coupled system of equations. The influence of fluid viscosity and other parameters on the natural vibration frequencies and critical velocities responsible for the loss of structural stability has been analyzed. The natural frequencies and the corresponding decrements of harmonic vibrations of rectangular plates located in the air and on the free liquid surface have been studied with the help of developed experimental setup. It has been found out that the damping coefficient corresponding to one vibration mode (bending or torsional) grows with an increase in the number of nodal lines. It has been demonstrated that this relation can be violated during the interaction of the plates with the liquid.

From the beginning of space era human being has launched more than 5500 rockets in space having different types of payload for various space mission carried out. These payloads, mostly satellites have many types of uses, ranging from earth observation to communication. These satellites, post usage hold no utilization but keep orbiting around the earth. This had leaded the space environment to be filled with such space deployed objects that we call as space debris. Such kind of accumulation of space debris is increasing gradually with each space mission carried out, and is posing a serious threat for our future space missions. Space debris around earth, if not resolved can become the most danger problem to upcoming space missions and research in future space exploration journey. Space debris is a very critical problem that would need an ample of time to come up with some feasible solution. Unfortunately, most of the proposed methods for space debris removal are not successfully functional. Whilekeeping in view, the shortcomings of the existing proposed methods for debris removal, we have reviewed a more practical method that could be implementedsuccessfully. We are proposing a combination ofthe already available technologies in a new way for scavenging the space yard. In this paper, we have studied advanced removal technique like-catching and capturing space debris, reuse of rocket systemand have proposedcost effective plans for removal of space junks from earth orbit using alaser ablation technique.

Experimental and numerical study for detection of rail defect