Long-term Flight Research Articles

Preparation and thermal insulation performance of Al2O3[sbnd]Y2O3[sbnd]SiO2 ternary composite aerogels with high specific surface area and low density

Against the background of global energy shortages and the need for long-term flight safety of aerospace vehicles, traditional silica aerogels have the problems of insufficient temperature resistance and poor thermal insulation at high-temperatures, and are no longer able to meet the demand. In this study, a series of monolithic Al2O3Y2O3SiO2 ternary aerogels were successfully synthesized via synchronous sol–gel and ethanol supercritical drying. Both the prepared aerogels and the calcined samples at 1000 °C exhibited a complete three-dimensional network structure and a high specific surface area (up to 675.7 m2/g and 214.4 m2/g), which was attributed to the supporting effect of the Al2O3 component on the overall skeleton and the inhibiting effect of the Y2O3 component on the crystal transformation. Mullite fiber reinforced Al2O3Y2O3SiO2 aerogel composites were synthesized by vacuum impregnation using mullite fiber felt as a matrix. The prepared sample exhibit very low thermal conductivity (as low as 0.079 W⋅m−1·K−1 at 1000 °C). In summary, the good structural stability and high temperature thermal insulation performance make Al2O3Y2O3SiO2 ternary aerogel have the potential of efficient service in more application scenarios. This study provides a product optimization reference idea for the thermal insulation material industry.

Rat bone responses to hindlimb unloading-reloading: Composition, BMD and mechanical properties

IntroductionBone loss in lower limbs under space microgravity condition can persist even after the astronauts return to Earth's gravitational environment. It is crucial to determine the extent and timing of bone recovery after spaceflight, especially for long-term flights. However, there is a lack of comprehensive descriptions of the recovery of various aspects of bone quality, particularly in terms of compositional characteristics that reflect changes in bone quality. Therefore, the objective of this study is to investigate the alterations in bone mineral density, composition characteristics, and mechanical properties of rat lower limbs during unloading (tail suspension) and the subsequent recovery loading period. MethodsRats were subjected to tail suspension for four weeks (TS4) followed by reloading for an additional four weeks. Bone mineral density (BMD) was measured by μ-CT and analyzed. The mechanical properties of the tibia were assessed by a three-point bending test, and the composition characteristics of bone tissue were evaluated using Raman spectroscopy. Regression analysis was performed to identify main component related to mechanical property. ResultsIn the metaphysis, BMD of the tibia significant decreased, particularly in trabecular bone. Upon reloading, only the cortical bone showed recovery. In the diaphysis, cortical bone remained unchanged during unloading but demonstrated delayed bone loss during the reloading period. Simultaneously, the mechanical properties of tibia experienced a substantial reduction after four weeks of unloading, The stiffness and maximum strength did not fully recover, though the elastic modulus and the ultimate strength were restored following the reloading process. Raman spectroscopy characterization found an increase in the carbonate substitution and crystal crystallinity of the diaphysis after 4 weeks of unloading. There was an intriguing alteration in the mineralized collagen ratio, that an increase was observed in the diaphysis while a decrease was observed in the metaphysis. During 4 weeks of reloading, the compositional characteristics of the diaphysis recovered earlier than those of the metaphysis, with the exception of crystallinity which remained unrecovered. Regression analysis indicated that carbonate replacement has a strong correlation to bone mechanical properties during the 4 weeks of unloading and subsequent 4 weeks of reloading. ConclusionsThe data obtained in this study highlight the incomplete recovery of bone mineral density, mechanical properties, and compositional characteristics during reloading in tail-suspended rats. These findings deepen our understanding of microgravity-induced bone loss and provide valuable information to develop interventions not only for astronauts but also for persons on earth during and after prolonged periods of unloading.

Planning the Optimal Reference Flight Path of an Aircraft Using a Terrain Map

In connection with the development of aviation technology, the expansion of the functionality of modern aircraft and the complication of the tasks being solved, additional stringent requirements are imposed on the accuracy of air navigation. Along with high accuracy, navigation autonomy is also required. The autonomy of aircraft navigation implies the navigation of an aircraft without the use of active radar facilities. In this article, to calculate the optimal reference flight path of an aircraft in a horizontal plane, the Bellman dynamic programming method is proposed using a digital terrain map. A technique, algorithms have been developed, and a numerical experiment has been carried out using fragments of a digital terrain map. High accuracy and autonomy of navigation are necessary, among other things, to ensure stealth (invisibility) of aircraft by ground-based radar facilities of a potential enemy in low-altitude flight mode. The best stealth of an aircraft flight in a low-altitude flight mode is achieved not only by flying around, but also by avoiding obstacles, due to the shielding properties of the earth’s surface. Autonomy of navigation provides periodic correction of the reference flight path during long-term flight, and high accuracy prevents aircraft collisions with the earth’s surface in low-altitude flight mode. The purpose of this work is to select the optimal reference trajectory (route) of an aircraft flight in the low-altitude flight mode. This article discusses a method developed based on the principle of dynamic programming for calculating the reference flight path in the horizontal plane depending on the DEM and the implementation of the algorithm based on the proposed method with a specific numerical example. The method makes it possible to calculate the optimal flight route, which provides the greatest secrecy of the aircraft in the low-altitude flight mode using the screening properties of the earth’s surface irregularities.

Catastrophic Failure Assessment of Sealed Cabin for Ultra large Manned Spacecraft in M/OD Environment

Hypervelocity impacts of Micrometeoroid and Orbital Debris (M/OD) may lead to catastrophic failure of long-term flight manned spacecraft in orbit. Risk assessment for manned spacecraft in M/OD environment is of great significance for the safety of human space missions. For typical catastrophic failure modes of manned spacecraft such as gas-leakage-induced astronaut hypoxia, sealed cabin fracture, and spacecraft breakup, catastrophic failure assessment method using critical perforation diameters and critical crack lengths of sealed cabins and critical fragment size of spacecraft breakup as failure criteria are proposed. In addition, corresponding modules of catastrophic failure assessment were developed and integrated with Meteoroid and Orbital Debris Assessment and Optimization System Tools, providing an effective assessment tool for researching on the safety of manned spacecraft. On the basis of which, catastrophic failure evaluation of sealed cabin for a specific ultralarge manned spacecraft in the M/OD environment was conducted, providing references for on-orbit mission safety evaluation.

Energy System Optimization and Simulation for Low-Altitude Solar-Powered Unmanned Aerial Vehicles

The accurate calculation of energy system parameters makes a great contribution to the long-term low-altitude flight of solar-powered aircraft. The purpose of this paper is to propose a design method for optimization and management of the low-altitude and long-endurance Unmanned Aerial Vehicles (UAV) energy system. In terms of optimization, the power input and output generated by solar panels and cruise thrust are calculated, and the energy balance of the UAV during flight is analyzed. In addition, in order to meet the energy consumption requirements of UAV during day and night flight, the influence of local environmental conditions (such as morning and evening clouds and night interference) on the aircraft is considered, and the remaining time indicator is designed to ensure long-term flight stability. Battery capacity is also estimated by the remaining time. This paper will describe extended criteria for optimization and extension methods to improve the stability and robustness of aircraft flight performance for multiple consecutive days. In addition, a design method for the UAV has been developed, which simulates and optimizes the parameters of the solar-powered UAV so that it has a wingspan of 5 m and a relative battery mass of 3 kg. The simulation in this paper describes in detail the aircraft taking off from 7 a.m. on the first day to verify the aircraft’s full day and night flight capability, and achieving the aircraft’s long flight on 22 June to meet the mission requirements of multi-day flights. It also analyzed and verified the performance at the edge of the 48 h flight time window on 21 April, which differs from the lighting in August. Finally, a flight experiment was completed on 9 August. The feasibility of the proposed method and process is verified in this paper along with the performance of the designed UAV, which will provide more guidance for future work.

Формирование и отображение видеоинформации в бортовых мультиспектральных системах улучшенного видения

The article considers the results of long-term research and real flight tests for developing a multichannel system for enhanced vision in difficult for aircraft crew visibility conditions. The multicomponent nature of the aggregate video signal generated by a multispectral video system is shown, justifying its representation in color and the need to develop a color indicator of the aircraft windshield to obtain a better quality of situational awareness for pilot compared to the capabilities of traditionally used monochrome indicators. A method for integrating monochrome images of multichannel enhanced vision system spectral channels into a color multicomponent image is proposed. For more natural perception of the resulting color images by the human eye, the spectrum of the spectral characteristics of the video channels is rearranged in the direction of decreasing wavelength. For the most common RGB color image format, the red component R of the display system records the image of the long-wave thermal range, the green component G records the image of the mid-wave infrared range, the blue component B records the image of the short-wave visible television range. The resulting pseudo-color image allows unambiguous restoring the original images. This proves the absence of information loss during image integration. Since there are no colored windscreen displays yet, a method for reproducing a pseudo-color image on a mono-chrome display is proposed. To convert a pseudo-color image to monochrome one, methods are used in which color contrasts are preserved in the form of tonal contrasts. The advantages of the proposed technology are demonstrated on real examples

Energy Acquisition of Solar-Powered Joint-Wing Aircraft Considering Mismatch Power Loss

Solar-powered aircraft can perform long-term flights with clean solar energy. However, the energy derived from solar irradiation is influenced by the time of year and latitude, which limits the energy acquisition ability of solar aircraft with a straight-wing configuration. Hence, unconventional configurations based on increasing wing dihedral to track the sun are proposed to improve energy acquisition at high-latitude regions in winter, which may involve power loss caused by mismatch in the photovoltaic system. However, mismatch loss is seldom considered and may cause energy to be overestimated. In this paper, the energy acquisition characteristics of a joint-wing configuration are presented based on the simulation of an energy system to investigate the mismatch power loss. The results indicate a 4~15% deviation from the frequently used estimation method and show that the mismatch loss is influenced by the curved upper surface, the severity of shading and the circuit configuration. Then, the configuration energy acquisition factor is proposed to represent the energy acquisition ability of the joint-wing configuration. Finally, the matching between the aircraft configuration and flight trajectory is analyzed, demonstrating that the solar-powered aircraft with an unconventional wing configuration is more sensitive to the coupling between configuration and trajectory.

История космической психологии и обзор современной проблематики

The article examines the features of space psychology development in Russian and American practice. The reasons of space psychology peculiarities in two countries are discussed, as they’ve gone from disunity and secrecy to international cooperation and joint work on key topics. In the article the main directions of research in the field of space psychology are considered which are necessary for the International Space Station crew and for the future long-term flights.

Oxidative Posttranslational Modifications of Blood Plasma Proteins of Cosmonauts after a Long-Term Flight: Part II

Oxidative Posttranslational Modifications of Blood Plasma Proteins of Cosmonauts after a Long-Term Flight: Part II

Neuropeptide ACP facilitates lipid oxidation and utilization during long-term flight in locusts.

Long-term flight depends heavily on intensive energy metabolism in animals; however, the neuroendocrine mechanisms underlying efficient substrate utilization remain elusive. Here, we report that the adipokinetic hormone/corazonin-related peptide (ACP) can facilitate muscle lipid utilization in a famous long-term migratory flighting species, Locusta migratoria. By peptidomic analysis and RNAi screening, we identified brain-derived ACP as a key flight-related neuropeptide. ACP gene expression increased notably upon sustained flight. CRISPR/Cas9-mediated knockout of ACP gene and ACP receptor gene (ACPR) significantly abated prolonged flight of locusts. Transcriptomic and metabolomic analyses further revealed that genes and metabolites involved in fatty acid transport and oxidation were notably downregulated in the flight muscle of ACP mutants. Finally, we demonstrated that a fatty-acid-binding protein (FABP) mediated the effects of ACP in regulating muscle lipid metabolism during long-term flight in locusts. Our results elucidated a previously undescribed neuroendocrine mechanism underlying efficient energy utilization associated with long-term flight.

Mechanism research of the laser propulsion of bulk graphene sponge material through high vacuum experiment

Qualitative and quantitative studies have shown that the laser propulsion of bulk graphene sponge material (LPGS) is efficient, green and stable, which has great value in long-term flight, light-driven actuator and optical-mechanical microsystem. However, its mechanism is still in dispute due to the lack of adequate experimental evidence, hindering its applications. In this work, LPGS is comparatively studied under the high vacuum (0.002 Pa) and the rough vacuum (6 Pa). It is observed that LPGS is significant in rough vacuum but disappears in high vacuum, which experimentally refutes the propulsion mechanism based on electron ejection, and confirms that the more reasonable explanation is the laser-induced Knudsen force. This work clears the discussion about the LPGS mechanism and provides an important theoretical basis for the practical use of LPGS.

State Estimation for HALE UAVs With Deep-Learning-Aided Virtual AOA/SSA Sensors for Analytical Redundancy

High-altitudelong-endurance (HALE) unmanned aerial vehicles (UAVs) are employed in a variety of fields because of their ability to fly for a long time at high altitudes, even in the stratosphere. Two paramount concerns exist: enhancing their safety during long-term flight and reducing their weight as much as possible to increase their energy efficiency based on analytical redundancy approaches. In this letter, a novel deep-learning-aided navigation filter is proposed, which consists of two parts: an end-to-end mapping-based synthetic sensor measurement model that utilizes long short-term memory (LSTM) networks to estimate the angle of attack (AOA) and sideslip angle (SSA) and an unscented Kalman filter for state estimation. Our proposed method can not only reduce the weight of HALE UAVs but also ensure their safety by means of an analytical redundancy approach. In contrast to conventional approaches, our LSTM-based method achieves better estimation by virtue of its nonlinear mapping capability.

Application of Carbon-Based Nanomaterials in Acid-Base Sensors

At present, long-term flight of carrier-based aircraft and other naval aviation equipment in high-salt, high-humidity environments will be subject to various environmental corrosion. The traditional means of monitoring aircraft corrosion is to seal water and prevent periodic inspections. The two monitoring methods are inefficient, and it is not easy to find the corrosion condition in the early stage of corrosion. When the corrosion really occurs, it will seriously threaten the safe flight of the aircraft and the safety of the pilot. Therefore, there is a need to develop an on-line monitoring sensor device for aircraft corrosion conditions to carry out real-time monitoring of aircraft acid-base corrosion (pH) conditions in high-salt, high-humidity marine environments. This paper mainly studies the application of carbon-based nanomaterials in acid-base sensors. In this paper, the acid-base sensor potential values at the same pH value are changed back and forth. In the initial state, the acid-base sensor potential values corresponding to pH = 3 are 385, 386, 379, and 392 mV, respectively. After 1500 s, the potential values of the acid-base sensor were 384, 383, 377, and 390 mV, and the three-phase hysteresis potential of the acid-base sensor was 1, 3, 2, and 2 mV, indicating that the acid-base sensor produced a small hysteresis potential. However, the amount of sensor drift is within a controllable range, and the response time of the acid-base sensor is relatively short regardless of the solution with different pH values added dropwise from acid to alkali or from alkali to acid. Therefore, the acid-base sensor has good hysteresis and recyclability.

Вопросы питания в межпланетных космических полётах

№1-2021 новая космическая эра пилотируемые космические полеты питание космонавтов Международная космическая станция рацион пищевой статус English NEW SPACE AGE NUTRITIONAL ISSUES ON INTERPLANETARY SPACE FLIGHTS The article analyzes the effectiveness of using existing power supply systems for short-term flights on transport manned ships and for long-term flights on the International Space Station (ISS). The article presents the characteristics of products that are suitable for use in space flight conditions and are currently used to complete rations for feeding cosmonaut crews. The existing problems are considered and the main directions of work on creating power supply systems for interplanetary flights and on planetary bases are outlined.

Impacts of Thermal and Mechanical Cycles on Electro-Thermal Anti-Icing System of CFRP Laminates Embedding Sprayable Metal Film.

The aircraft electro-thermal anti-icing system that can guarantee flight safety may be affected by periodic heating and cyclic aerodynamic force during long-term flight missions, which seems to be a potential threat to ice protection. This paper aims to investigate the impacts of thermal and mechanical cycles on heating elements of the electro-thermal anti-icing system. Specimens were manufactured with CFRP (carbon fiber reinforced polymer) laminated composite, glass fiber prepreg and copper screen, in which sprayable metal film (SMF) was embedded as the heating element. The study focuses on electric resistance variation of SMF and functional fatigue life under the cycling load. Thermal cycling tests were carried out in an insulated chamber where the specimens were heated up to 80 °C and then cooled down to −55 °C for 1000 cycles. Mechanical cycling tests were conducted on a fatigue testing machine where the specimens were imposed on tension-compression loading for 106 cycles. Results showed that the electric resistance of SMF increased with the number of loading cycles. The resistance was increased by 20% and the heating power was decreased by 16.67% after 1000 thermal cycles. During the mechanical cycling tests, it was found that the heating element was destructed before the structural failure, which indicated that the fatigue life of function was lower than that of the structure.

Deep Membrane Proteome Profiling of Rat Hippocampus in Simulated Complex Space Environment by SWATH

Despite the development and great progress in the field of space biology, the astronauts are still facing many challenges in space. The space environment in which astronauts stay includes microgravity, noise, circadian rhythms disorder, and confinement, which has deep effect both on the physiology and psychology of astronauts. It was reported that long-term flight could cause the astronauts’ anxiety and depression. However, the underlying mechanism is not yet fully understood. Therefore, in the present study, the rat tail suspension model with noise, circadian rhythms, and confinement was employed to simulate complex space environment. We found that the rats exhibited the depressive-like behavior by the sucrose preference, forced swimming, and open-field tests. The membrane proteome of the rat hippocampus was investigated by “SWATH quantitation” technology both in control and simulated complex space environment (SCSE) groups. Out of 4520 quantified proteins, 244 differentially expressed membrane proteins were obtained between the SCSE and control rats, which were functionally enriched in a series of biological processes, such as translation, protein phosphorylation, brain development, endocytosis, nervous system development, axonogenesis, and vesicle-mediated transport. We found a reduction level of neurexin-2, the light, medium, heavy polypeptide of neurofilament, rab 18, synaptogyrin 1, and syntaxin-1A and an increase level of neuroligin-1, munc18, snapin, synaptotagmin XII, complexin-1, etc., which may play a key part in the development of depression. Furthermore, GSK-3 β protein was upregulated in mass spectrometry, which was further validated by western blotting. The results of the study do the favor in designing the effective countermeasures for the astronauts in the future long-term spaceflight.

Progress and Enlightenment of Intelligent On-orbit Operation of International Space Station

The mission of a space station that is known as the big platform of near-earth space is to enable long-term flight to explore space. As the ever-increasing number of on-orbit missions, it is a challenge to manage an effective on-orbit project. With the deep integration of artificial intelligence and space technology, the on-orbit operation of a space station has gradually developed to be intelligent. Therefore, the intelligent operation of spacecraft has become an inevitable trend. This paper focuses on the development of on-orbit intellectualization at the International Space Station (ISS) and the application of artificial intelligence technology in its health management, mission planning and scheduling, mission operation and human-computer interaction. It is hoped that the research will contribute to the intelligent on-orbit operation in China.

Analysis and Synthesis of Control Systems for Spacecraft Solar Arrays

The paper is devoted to the problem of creating highly reliable power supply systems for spacecrafts intended for long-term autonomous flights. Within its framework, the problem of synthesizing a control system for solar arrays is being solved. To solve this problem, a mathematical model of a solar panel was compiled, and a study of its static and dynamic characteristics was carried out. It was found that when the solar panel is controlled using a shunt switch with pulse-width modulation, resonance phenomena appear in the system, leading to an unacceptable change in the polarity of voltages on the photocells. The operating conditions of the solar panels, which exclude the occurrence of the indicated alternating voltages, are found, and appropriate recommendations are given for the choice of the quantization frequency in the system. On the basis of the recommendations received, the transition to a quasi-continuous representation of the control system was carried out, and a graphic-analytical synthesis of the controller providing the required quality indicators of the system was carried out. To ensure the survivability of the power supply system, a method is proposed for the hierarchical organization of the interaction of solar panels, which reproduces the homeostatic properties of biological structures in the system. This property is provided by automatic transfer of control to subsequent levels of the hierarchy as the energy resources of the previous levels are exhausted. In addition, selective control is applied only to that part of the total generated power, which is sufficient to counter the current disturbing influences on the system. This approach to control prevents cascading failures in the system. The paper presents simulation models on which all theoretical positions and methods proposed in the work are tested.

Impact of climate variabilities on trans-oceanic flight times and emissions during strong NAO and ENSO phases

This study investigates the impact of the North Atlantic Oscillation (NAO) and El Niño Southern Oscillation (ENSO) on trans-oceanic round-trip flight times and consequent CO2 emissions over the north Atlantic and eastern Pacific regions. For three strongest winter periods of both polarity during 1979–2016, daily mean wind data are used to compute the wind-optimal flight trajectories at cruising altitudes. Results show that intensified upper-level jet streams during the +NAO winters provide stronger headwinds for westbound flights between the eastern US and the western Europe. This causes 4.24 ∼ 9.35 min increase in an averaged total round-trip journey time during the +NAO compared to −NAO winters. In the eastern Pacific region, the jet stream is extended eastward towards the southwestern US during the +ENSO period, which lengthens the travel time for westbound flights between Hawaii and the west coast of the US. The increase in travel time of westbound flights is greater than the corresponding decrease in travel time for eastbound flights, resulting in a 5.92 ∼ 8.73 min increase of the averaged total round-trip time during the +ENSO compared to the −ENSO periods. Extrapolating these results to overall trans-oceanic air traffic suggests that aircraft will take a total of 1908 ∼ 4207 (888 ∼ 1309) extra hours during the +NAO (+ENSO) than the −NAO (–ENSO) winters over the North Atlantic (Eastern Pacific) regions, requiring 6.9 ∼ 15 (3.2 ∼ 4.7) million US gallons of extra fuel burned at a cost of 21 ∼ 45 (9.6 ∼ 14) million US dollars and 66 ∼ 144 (31 ∼ 45) million kg of extra CO2 emissions to all trans-oceanic traffic. In +ENSO and +NAO winters, the chances of a given flight having a slower round-trip flight time with more fuel burn and CO2 emissions are 2–10 times higher than in a −ENSO or −NAO winter. These results have significant implications for the planning of long-term flight routes with climate variability.

Post-Translational Oxidation Modifications of Blood Plasma Proteins of Cosmonauts after a Long-term Flight: Part I

The balance of production and elimination of free radicals and reactive oxygen species is disturbed in the human body during a space flight. Oxidative stress is a common pathogenetic link in the violation of the functions and structure of various body tissues. The main cellular components, such as DNA, lipids, and proteins, undergo oxidative damage. In this study, proteomic methods were used to analyze the frequency of detection of oxidative post-translational modifications of blood plasma proteins obtained from Russian participants in International Space Station (ISS) flights. The effect of the oxidative modification detected after space flight on the functional features of protein groups that regulate the hemostasis and complement activation cascade is examined. According to published data, the increase in oxidative post-translational modifications of proteins in the hemostasis system affects not only the protein structure but also the fibrin formation, as well as its viscoelastic and biochemical properties. Oxygenation of proteins with oxidation-sensitive methionine residues, including apolipoprotein A-I, thrombomodulin, and von Willebrand factor, increases the risk of developing vascular diseases and thrombosis. Oxidized phospholipids are deposited in the vessel wall, potentiating atherosclerotic changes. It was shown that the oxidative modification of the key protein, clusterin, changed the regulation of the complement cascade, as well as the association of the immune system with the coagulation cascade.