Real Space Missions Research Articles

Space Analogs and Behavioral Health Performance Research review and recommendations checklist from ESA Topical Team.

Space analog research has increased over the last few years with new analogs appearing every year. Research in this field is very important for future real mission planning, selection and training of astronauts. Analog environments offer specific characteristics that resemble to some extent the environment of a real space mission. These analog environments are especially interesting from the psychological point of view since they allow the investigation of mental and social variables in very similar conditions to those occurring during real space missions. Analog missions also represent an opportunity to test operational work and obtain information on which combination of processes and team dynamics are most optimal for completing specific aspects of the mission. A group of experts from a European Space Agency (ESA) funded topical team reviews the current situation of topic, potentialities, gaps, and recommendations for appropriate research. This review covers the different domains in space analog research including classification, main areas of behavioral health performance research in these environments and operational aspects. We also include at the end, a section with a list or tool of recommendations in the form of a checklist for the scientific community interested in doing research in this field. This checklist can be useful to maintain optimal standards of methodological and scientific quality, in addition to identifying topics and areas of special interest.

LaB6 hollow cathode with a novel graphite heater

In this study, the design and experimental characterization of a LaB6 hollow cathode utilizing a novel heater made of graphite are presented. Hollow cathodes commonly use heaters where a refractory metal wire is wound around a high temperature ceramic insulator with grooves. These heaters have issues related to thermal fatigue and the recrystalization embrittleness of the heater wire at high temperatures causing the cathode to malfunction, leading to short lifetime. Rather than using refractory metals, a heater made of graphite is designed and integrated into an existing hollow cathode. The graphite can be manufactured easily and does not show any embrittlement at high temperatures, which increases its operational life time. Additionally, due to its lower sputtering yield, undesirable operational conditions are eliminated. A zig-zag shape is used to tailor the geometry to reach desired resistance value of the heater. The presented graphite-heater eliminates these problems as long as enough care is taken in its initial manufacturing and assembly stage. Additionally, the design of the graphite-heater can be modified in such a way to provide heating to a targeted area, which help decrease the required heater power as well as increase the heating speed of the cathode insert material. Successful tests of the hollow cathode with the novel graphite heater indicate long lifetime and steady operation performance, making it suitable for use in real space missions.

New Sizing Methodology and Efficiency Analysis of Satellite’s Electrical Power Subsystem

This paper describes a novel methodology to improve the preliminary design and efficiency analysis of the satellite’s electrical power subsystem. Several studies have addressed this issue by proposing a solar array sizing method based on the use of fixed efficiency paths during sunlight and eclipse periods. Indeed, these studies restrict the use of the battery for eclipse periods, and thus the solar array is sized to support the peak power loads on its own. To the authors’ knowledge, no one has so far deeply and jointly analyzed the influence of the power profile demand, the use of the battery during sunlight periods, and the architecture on the efficiency paths to size the electrical power subsystem. This work offers a methodology that takes into account these variables to better estimate the global efficiency of the electrical power subsystem and, consequently, to refine the first design iterations of a satellite. This methodology is particularized for the most common architectures based on power and voltage bus regulation, although it can be implemented in more complex architectures. A case study involving a real space mission, the UPMSat-2 (a 50 kg satellite launched in September 2020), is conducted to test this methodology.

Development status, key technologies, and prospects of neutralizer-free ion thrusters

<p indent="0mm">The ion thruster is one of the most widely used electric thrusters and is famous for its high specific impulse and efficiency, but there are some shortcomings of the conventional ion thruster, such as the complex structure and the difficulty of miniaturization. One of the most attractive solutions to make up for these shortcomings is the neutralizer-free ion thruster which can reduce the volume and mass of the ion propulsion system and improve the system reliability by canceling the neutralizer system. In this review, the principles, strengths, and weaknesses of the conventional ion thruster are summarized, which leads to the concept of the neutralizer-free ion thruster. Combined with the operations of ion thrusters in real space missions, the advantages of removing neutralizer systems are analyzed. According to the neutralization methods, the neutralizer-free ion thruster can be divided into two types which are the electronegative ion thruster and RF (radio-frequency) ion thruster based on the self-bias effect. At present, the neutralizer-free ion thruster is mainly developed in Europe, Japan, and the United States of America. Researchers in China also perform some numerical and experimental studies on the neutralizer-free ion thruster, but there is still no report on the relatively mature prototype model. Lastly, based on the application requirements of the space propulsion and characteristics of the neutralizer-free ion thruster, the key technologies of the neutralizer-free ion thruster are discussed: (1) For the sake of prolonging the service life and improving the beam performance, the choice of propellant in neutralizer-free ion thrusters, especially the electronegative ion thruster where the propellant should be electronegative, needs more consideration than conventional ion thrusters. (2) The voltages applied on the grid system are generally AC voltages. Thus, to extract the collimated ion beams with high neutralization degree, the determination of the frequency and amplitude of grid voltages should consider many factors, such as the propellant type, insulation design, and plasma properties. (3) The adjustment of the working mode becomes more complex in the neutralizer-free ion thruster, since it is more difficult to adjust the AC grid voltage than conventional DC grid voltages and the relationship between the AC grid voltage and thruster performance also needs further investigations. (4) The magnetic filter plays an important role in the electronegative ion thruster, but it should be optimized because it increases the volume and weight of the thruster and weakens the advantages of the neutralizer-free ion thruster. (5) The ion-ion plasma in the electronegative ion thruster and the sheath near the grid with AC voltages make the plasma characteristics in the neutralizer-free ion thruster quite different from the conventional ion thruster. It is critical to perform more studies on the plasma physics of the neutralizer-free ion thruster to better design the thruster and adjust its performance. Accordingly, it’s concluded that the investigations of the choice of the propellant, design of the magnetic filter and grid system, plasma physics, and flexible regulation method of the grid voltage should be focused on. Moreover, to further understand the performance of the neutralizer-free ion thruster, new methods for diagnosing this new type of thruster need to be developed.

Impact Pressure Distribution Recognition for Large Non-Cooperative Target in Ground Detumbling Experiment

During the contact between the detumbling end-effector and large non-cooperative target, the recognition of impact pressure distribution is important for estimating the success rate of detumbling mission. To figure out the pressure trends, the ground experiments before the real space mission are necessary. However, due to the drawbacks of the pressure array-like sensor, dynamic characteristics of impact, and unavoidable noise, the accurate dynamic pressure distribution is hard to obtain. In this letter, we propose a recognition method, Impact Pressure Distribution Recognition. The proposed method can quickly generate dynamic impact pressure distribution without limitation on sensor accuracy through pressure data supplement and area correction based on contact model. The analysis results show that our method can efficiently recognize multiple distributed pressure and rebuild the more accurate impact pressure distribution.

Super-Twisting Sliding Mode Control Law Design for Attitude Tracking Task of a Spacecraft via Reaction Wheels

The attitude control has been recognized as one of the most important research topics for spacecraft. If the desired attitude trajectory cannot be tracked precisely, it may cause mission failures. In the real space mission environment, the unknown external perturbations, for example, atmospheric drag and solar radiation, should be taken into consideration. Such external perturbations could deviate the precision of the spacecraft orientation and thereby lead to a mission failure. Therefore, in this paper, a quaternion-based super-twisting sliding mode robust control law for the spacecraft attitude tracking is developed. The finite time stability based on the formulation of the linear matrix inequality (LMI) is also provided. To avoid losing the control degree of freedom due to the certain actuator fault, a redundant reaction wheels configuration is adopted. The actuators distribution associated force distribution matrix (FDM) is analyzed in detail. Finally, the reference tangent-normal-binormal (TNB) command generation strategy is implemented for simulating the scenario of the space mission. Finally, the simulation results reveal that the spacecraft can achieve the desired attitude trajectory tracking demands in the presence of the time-varying external disturbances.

The Effects of Spaceflight Factors on the Human Plasma Proteome, Including Both Real Space Missions and Ground-Based Experiments.

The aim of the study was to compare proteomic data on the effects of spaceflight factors on the human body, including both real space missions and ground-based experiments. LC–MS/MS-based proteomic analysis of blood plasma samples obtained from 13 cosmonauts before and after long-duration (169–199 days) missions on the International Space Station (ISS) and for five healthy men included in 21-day-long head-down bed rest (HDBR) and dry immersion experiments were performed. The semi-quantitative label-free analysis revealed significantly changed proteins: 19 proteins were significantly different on the first (+1) day after landing with respect to background levels; 44 proteins significantly changed during HDBR and 31 changed in the dry immersion experiment. Comparative analysis revealed nine common proteins (A1BG, A2M, SERPINA1, SERPINA3, SERPING1, SERPINC1, HP, CFB, TF), which changed their levels after landing, as well as in both ground-based experiments. Common processes, such as platelet degranulation, hemostasis, post-translational protein phosphorylation and processes of protein metabolism, indicate common pathogenesis in ground experiments and during spaceflight. Dissimilarity in the lists of significantly changed proteins could be explained by the differences in the dynamics of effective development in the ground-based experiments. Data are available via ProteomeXchange using the identifier PXD013305.

An Approach for Geostationary Satellite Mode Management

In each mission phase, a satellite is characterized by a well-defined set of modes. They define a clear configuration of the spacecraft subsystems and have specific operational implications. In this paper, we present an approach for geostationary earth observation satellite mode management during both the Launch and Early Orbit phase and the full operational phase. It draws on a real space mission project currently carried out at OHB System AG. The configurations of the Attitude and Orbit Control System are also analyzed, their operational meaning and the relationship with the satellite modes. It is also explained how on-board autonomy requirements play a relevant role in the satellite mode definition and management. Geostationary satellites can usually be operated in a quasi real-time fashion, therefore a limited level of on-board autonomy can be sufficient. However, they can be characterized by high availability requirements and have a need for ground operation reduction, which can lead to an increased level of on-board autonomy in satellite mode management.

Nano-graphite cold cathodes for electric solar wind sail

The nanographite (NG) films consisting of tiny graphite crystallites (nanowalls) are produced by carbon condensation from methane–hydrogen gas mixture activated by a direct current discharge. High aspect ratio and structural features of the NG crystallites provides efficient field electron emission (FE). Applicability and performance of the NG films in an electron gun (E-gun) of a solar wind thruster system with an electric sail (E-sail) is tested. The long-term tests are demonstrated suitability of E-gun assembly with the NG cathodes for the real space missions. The results of the tests are analyzed and physical mechanisms of the cathode aging and practical methods for improvement performance of the E-gun are proposed.

Special Issue on Space Robotics

This special issue presents a series of papers that all have two subjects in common: (1) of course they all deal with the application of robots in a space scenario but (2) they all deal with integration, which is in fact a very important aspect of both the space scenario as well as Artificial Intelligence and Robotics research in a broader sense. Space robotics can actually be described as the ultimate test for AI and Robotics as it leaves no room for excuses: Once a system is deployed it basically stands on its own. Of course there are ways to communicate with the system, especially if the system stays in earth orbit, but even this communication has some shortcomings and pitfalls, as delays and blackouts are common place. The most interesting systems however, in the sense of requiring a solid AI and Robotics background, are those that go beyond earth orbit heading for exploration of the solar system—whether that is as a probe just bypassing celestial bodies like asteroids, moons or planets, or systems that actually head out to touch down on the surface of an extraterrestrial body. Whatever these systems may need, in terms of hardware and software, during their missions in essence they must have it at the time they are launched. If one considers a mission like that of the mars rovers Spirit and Opportunity that today lasts for more than 6 years, it is hard to believe that anybody in the design team could actually foresee all of the—in space mission slang: undefined events that these systems have encountered. Some of these events even made it into the news, as e.g., when the system got stuck in a sand pit and it took the control team weeks to find a solution of how to get the thing back out again. It finally worked out but it points to a clear shortcoming of today’s space robots, which is their lack of autonomy and ability to learn new solutions that have not been programmed upon design (launch) time. This ability would be key to survival for a system that would have to travel out of reach of any communication with earth and that would therefore be on its own to deal with problems as described above. This is where it will be mandatory for the system to have a means of restructuring or reconfiguring itself according to the changed situation. The restructuring may actually be meant in terms of a hardware related process that, e.g., would exchange a broken gripper for a new one that the system carried along as a spare part (requiring basically a mechanical solution) or it could be a reconfiguration of software components like a specific odometry model that needs to be replaced as a consequence of a failure or just aging in the actuators. This special issue presents new approaches as well as integration efforts to tackle the challenges that space robotics offers. Many if not all of the presented approaches are in early stages of development and would not be able to fly in the way they are presented here. In space robotics as in space activities in general we know the term Technology Readiness Level (TRL) which refers to the level of maturity of a specific technology to actually be used in a real space mission. In these terms the systems presented here range from 1 to 3 (maybe 4) meaning that they are ranging from a description of the basic principle (TRL 1) to testing the technology in a laboratory setup (TRL 4). For university science teams it is difficult to go beyond this stage and to actually build and test a prototype in the realistic environment—space—(TRL 5) or even a fully qualified flying system (TRL 9). These steps require so much resources that F. Kirchner (&) Robotics Innovation Center, Deutsches Forschungszentrum fur Kunstliche Intelligenz (DFKI), 28359 Bremen, Germany e-mail: frank.kirchenr@dfki.de

Study of individual and group affective processes in the crew of a simulated mission to Mars: Positive affectivity as a valuable indicator of changes in the crew affectivity

The success of a long-duration space mission depends on various technical demands as well as on the psychological (cognitive, affective, and motivational) adaptation of crewmembers and the quality of interactions within the crew. We examined the ways crewmembers of a 520-day simulated spaceflight to Mars (held in the Institute for Biomedical Problems, in Moscow) experienced and regulated their moods and emotions. Results show that crewmembers experienced predominantly positive emotions throughout their 520-day isolation and the changes in mood of the crewmembers were asynchronous and balanced. The study suggests that during the simulation, crewmembers experienced and regulated their emotions differently than they usually do in their everyday life. In isolation, crewmembers preferred to suppress and neutralize their negative emotions and express overtly only emotions with positive valence. Although the affective processes were almost invariable throughout the simulation, two periods of time when the level of positive emotions declined were identified. Regarding the findings, the paper suggests that changes in positive affectivity could be a more valuable indicator of human experience in demanding but professional environments than changes in negative affectivity. Finally, the paper discusses the phenomenology of emotions during a real space mission.

THE PERIGEO PROJECT: INERTIAL AND IMAGING SENSORS PROCESSING, INTEGRATION AND VALIDATION ON UAV PLATFORMS FOR SPACE NAVIGATION

Abstract. The PERIGEO R&amp;amp;D project aims at developing, testing and validating algorithms and/or methods for space missions in various field of research. This paper focuses in one of the scenarios considered in PERIGEO: navigation for atmospheric flights. Space missions heavily rely on navigation to reach success, and autonomy of on-board navigation systems and sensors is desired to reach new frontiers of space exploration. From the technology side, optical frame cameras, LiDAR and inertial technologies are selected to cover the requirements of such missions. From the processing side, image processing techniques are developed for vision-based relative and absolute navigation, based on point extraction and matching from camera images, and crater detection and matching in camera and LiDAR images. The current paper addresses the challenges of space navigation, presents the current developments and preliminary results, and describes payload elements to be integrated in an Unmanned Aerial Vehicle (UAV) for in-flight testing of systems and algorithms. Again, UAVs are key enablers of scientific capabilities, in this case, to bridge the gap between laboratory simulation and expensive, real space missions.

Graph-tree-based software control flow checking for COTS processors on pico-satellites

This paper proposes a generic high-performance and low-time-overhead software control flow checking solution, graph-tree-based control flow checking (GTCFC) for space-borne commercial-off-the-shelf (COTS) processors. A graph tree data structure with a topology similar to common trees is introduced to transform the control flow graphs of target programs. This together with design of IDs and signatures of its vertices and edges allows for an easy check of legality of actual branching during target program execution. As a result, the algorithm not only is capable of detecting all single and multiple branching errors with low latency and time overheads along with a linear-complexity space overhead, but also remains generic among arbitrary instruction sets and independent of any specific hardware. Tests of the algorithm using a COTS-processor-based on-board computer (OBC) of in-service ZDPS-1A pico-satellite products show that GTCFC can detect over 90% of the randomly injected and all-pattern-covering branching errors for different types of target programs, with performance and overheads consistent with the theoretical analysis; and beats well-established preeminent control flow checking algorithms in these dimensions. Furthermore, it is validated that GTCGC not only can be accommodated in pico-satellites conveniently with still sufficient system margins left, but also has the ability to minimize the risk of control flow errors being undetected in their space missions. Therefore, due to its effectiveness, efficiency, and compatibility, the GTCFC solution is ready for applications on COTS processors on pico-satellites in their real space missions.

Predicting UV sky for future UV missions

Abstract Software simulators are now widely used in all areas of science, especially in application to astronomical missions: from instrument design to mission planning, and to data interpretation. We present a simulator to model the diffuse ultraviolet sky, where the different contributors are separately calculated and added together to produce a sky image of the size specified by the instrument requirements. Each of the contributors to the background, instrumental dark current, airglow, zodiacal light and diffuse Galactic light, depends on different factors. Airglow is dependent on the time of day; zodiacal light depends on the time of year, angle from the Sun and from the ecliptic; diffuse UV emission depends on the line of sight. To provide a full description of the sky along any line of sight, we have also added stars. The UV background light can dominate in many areas of the sky and severely limit viewing directions due to overbrightness. The simulator, available as a downloadable package and as a web-based tool, can be applied to preparation of real space missions and instruments. For demonstration, we present the example use for the two near-future UV missions: UVIT instrument on the Indian Astrosat mission and a new proposed wide-field (∼1000 square degrees) transient explorer satellite.

Rendezvous Simulation for On-Orbit Servicing Missions Using Advanced Robotic Technology

Increasing complexity and costs of satellite missions promote the idea of extending the operational lifetime or improving functionalities/performance of a satellite in orbit instead of simply replacing it by a new one. Further, satellites in orbit can severely be affected by aging or degradation of their components and systems as well as by consumption of available resources. These problems may be solved by satellite on-orbit servicing (OOS) missions. One of the critical issues of such a mission is to ensure a safe and reliable Rendezvous and Docking (RvD) operation performed autonomously in space. Due to the high risk associated with an RvD operation, it must be carefully analyzed, simulated and verified in detail before the real space mission can be launched. This paper describes a ground-based hardware-in-the-loop RvD simulation facility. Designed and built on 2-decade experience of RvD experiment and testing, this unique, high-fidelity simulation facility is capable of physically simulating the final approach within 25-meter range and the docking/capture process of an on-orbital servicing mission. Additionally this paper presents first results of hardware in the loop simulations for a rendezvous process to a non-cooperative target.

Use of industrial robots for hardware-in-the-loop simulation of satellite rendezvous and docking

One of the most challenging and risky operations for spacecraft is to perform rendezvous and docking autonomously in space. To ensure a safe and reliable operation, such a mission must be carefully designed and thoroughly verified before a real space mission can be launched. This paper describes the control strategy for achieving high fidelity contact dynamics simulation of a new, robotics-based, hardware-in-the-loop (HIL) rendezvous and docking simulation facility that uses two industrial robots to physically simulate the 6-DOF dynamic maneuvering of two docking satellites. The facility is capable of physically simulating the final approaching within a 25-meter range and the entire docking/capturing process for a satellite on-orbit servicing mission. The key difficulties of using industrial robots for high-fidelity HIL contact dynamics simulation were found and different solution techniques were investigated in the presented project. An admittance control method was proposed to achieve the goal of making the robots in the HIL simulation process match the impedance of the two docking satellites. Simulation study showed the effectiveness and performance of the proposed solution method.

Methods for Spacecraft Avionics Protection Against Space Radiation in the Form of Single-Event Transients

This paper presents a design philosophy for protecting spacecraft avionics from the effects of single-event transients caused by high-energetic charged particles in the space environment. The design philosophy has resulted in a proven concept over the many years of actual implementation in real avionics in real space missions. Only an overview of this design philosophy is presented. The paper first addresses the science of the space environment as it relates to high-energy charged particles. It includes the derivations of important parameters in high-energy particle physics as it applies to interactions with semiconductor electronic in component integrated circuits. The paper then transitions to explore some general methodologies widely used in the industry to control the damaging effects of single-event transients caused by the space environment. The paper then shifts emphasis to the main subject of design methods and philosophies, with examples of how spacecraft avionics can be designed and built with a certain level of immunity against the possible catastrophic effects of single-event transients. These design principles are presented briefly, but with enough detail to provide a general overview.

Electromagnetic Particle‐In‐Cell simulation on the impedance of a dipole antenna surrounded by an ion sheath

We have newly developed a numerical tool for the analysis of antenna impedance in plasma environment by making use of electromagnetic Particle‐In‐Cell (PIC) plasma simulations. To validate the developed tool, we first examined the antenna impedance in a homogeneous kinetic plasma and confirmed that the obtained results basically agree with the conventional theories. We next applied the tool to examine an ion‐sheathed dipole antenna. The results confirmed that the inclusion of the ion‐sheath effects reduces the capacitance below the electron plasma frequency. The results also revealed that the signature of impedance resonance observed at the plasma frequency is modified by the presence of the sheath. Since the sheath dynamics can be solved by the PIC scheme throughout the antenna analysis in a self‐consistent manner, the developed tool has feasibility to perform more practical and complicated antenna analyses that will be necessary in real space missions.