Space Capsule Research Articles

The Radiative Gas Dynamics of a Descent Space Capsule under Conditions of Orbital and Superorbital Entry into the Earth’s Atmosphere

The Radiative Gas Dynamics of a Descent Space Capsule under Conditions of Orbital and Superorbital Entry into the Earth’s Atmosphere

Comparison of Calculation Data on the Radiative and Convective Heating of Space Capsules Obtained with Correlation and Computer Models

Comparison of Calculation Data on the Radiative and Convective Heating of Space Capsules Obtained with Correlation and Computer Models

Numerical simulation of thermal comfort in microgravity-confined space

To investigate the thermal environment in a crewed space capsule, the velocity field, water vapor concentration field, local Nusselt number, and thermal comfort in microgravity are studied by numerical simulation. The results show that (a) gravity has an essential effect on the cabin flow field and personnel heat exchange. When the air supply velocity is less than 0.45 m/s, the average Nussert number on the body surface under normal gravity is more significant for the top air supply system. On the contrary, when the air supply velocity is higher than 0.45 m/s, the average Nussert number on the body surface under microgravity is larger. (b) In microgravity, due to the weakening of natural convection. Water vapor accumulates around the human body, increasing local relative humidity. When the relative humidity rises from 20% to 80%, the standard effective temperature rises by 1.6°C. (c) By analyzing the SET* under each working condition, we can conclude that the impact of personnel activity rate on Comfortable Environment Condition is weak under microgravity. When the air supply speed equals 0.06 m/s, indoor thermal comfort could be improved by increasing the lower temperature limit value or decreasing the upper humidity limit value of the Comfortable Environment Condition.

Thoughts about the Life Periods of our Earth and why we are not able to Better our Climate?

Before 2012, when the first NASA Voyger 1 space capsule after more years long travel left our solar systeme and entered the interstellar space, it was believed that in this territory was only vacuum. In spite of this hypotheses the instruments of the space capsule measured increasing quantity of plasma/cosmic ray/flux. In november of 2018 the Voyger 2 confirmed the before mentioned result. So today we must accepet the fact that the number of the high energy electrically charged particles have increased in the interastellar space instead of vacuum. Such particles have been emitted by our Sun, too. The name of this ray/flow is Sun wind and its particles have arrived at our Earth. We only mentioned this example to demonstrate that at present our knowledge about the Universe is somewhat hypothetical. In spite of this fact we try to summarize our thoughts connected with the life of our Earth on the basis of retrospective data and our own calculations.

Radiative Coefficients and Their Influence on In-Depth Heating of Porous Ablators

High entry speeds and exotic planetary gases can result in significant radiative heat loads on space capsules. The mechanism behind the transport of radiative signatures is fundamentally different from the conductive mode of energy transport, and penetration of radiative signatures depends on the radiative coefficients of the thermal protection system (TPS) material that protects the space capsule. The radiative coefficients of carbon-based and silica-based fibrous materials have been computed as functions of wavelength using the photon path length Monte Carlo method by explicitly accounting for the microstructure of the material. Significant variations in the radiative coefficients are observed at wavelengths that are relevant to shock-layer emissions. Although carbon-based fibrous materials exhibit higher absorption coefficients in comparison to silica-based systems, the absorption coefficients of carbon-based material drop by two orders of magnitude in the range of 100–200 nm. The radiative coefficients of carbon-based fibrous material are seen to be dominated by scattering and absorption with minimal transmission. However, the transmission coefficients for the silica system dominated the radiative coefficients in the range of 100–1000 nm, which corresponds to most shock-layer emissions. The radiative coefficients are used to solve the radiative transfer equation using the P-1 approximation to obtain the in-depth radiative heat flux. The total energy equation for decomposing porous TPS materials is solved with the radiative heat flux from the P-1 approximation and the conductive heat flux using the Fourier law. It is observed that peak temperatures inside the material are higher when radiative transport is explicitly accounted for through the P-1 approximation. Small variations in the absorption coefficient of the silica-based materials also affected the in-depth temperature profiles. Additionally, a broader temperature distribution is obtained inside the material with a low absorption coefficient, and the charring density profiles are influenced by the radiative heat flux. This study demonstrates that it is important to include radiative transport in material response solvers, and radiative coefficients must be accurately computed by accounting for the microstructure of the material.

Analytical Method of Calculating Reliability Sensitivity for Space Capsule Life Support Systems

Several fields within the social and technical sciences have identified the importance of theoretical and practical research into complex systems. The sensitivity of these systems is one of the primary focuses. The capsule’s high-pressure oxygen supply system (HPOSS) prepares a complex system with complex interconnections. The reliability of HPOSS cannot be reduced to a single equivalent component or block by combining series and parallel reductions. The aim of this paper is to demonstrate the application of mathematical detection tests to HPOSS in order to assess the sensitivity of the reliability of complex systems. Using the matrix-based minimal cut methodology and the linear sensitivity model of system reliability, the critical system illustrates the suggested methodologies and their relevance to investigating the sensitivity of complex interconnected systems.

The Decision-Making Process of China's Human Spaceflight Program

This article thoroughly examines the decision-making processes involved in the revival of China's human spaceflight program and debates over whether China's space program should begin with the development of a human space capsule or space shuttle. The authors discuss high-level decision-makers’ attitudes toward human spaceflight, the Chinese government's emphasis on preliminary research on human space programs and achieving technological catch-up with other countries, debates over whether space shuttles or human spacecrafts should be prioritized, and the final decision-making process of the Central Committee of the Communist Party of China (CPC) regarding the implementation of the human space program. In the light of the development of space shuttles in the United States and the Soviet Union and the progress of multiple reusable space shuttles and spaceplanes projects in Europe, a considerable number of experts and involved institutions in China have suggested prioritizing the development of space shuttles. Considering China's current situation, time and cost factors, level of technological advancement, and the difficulty of the task, a final proposal for developing a disposable human space capsule was submitted by China's Commission of Science, Technology, and Industry for National Defense (COSTIND) and the Ministry of Space Industry. In 1992, the Central Committee officially approved a three-step strategy for China's human spaceflight program. In the subsequent long-term operation, the US space shuttle failed to meet the expected goals, such as cost-effectiveness, safety, and flexibility of use, which could justify China's decision to prioritize the development of human spaceflight.

Growth Behavior and Transcriptome Profile Analysis of Proteus mirabilis Strain Under Long- versus Short-Term Simulated Microgravity Environment.

Spaceflight missions affect the behavior of microbes that are inevitably introduced into space environments and may impact astronauts’ health. Current studies have mainly focused on the biological characteristics and molecular mechanisms of microbes after short-term or long-term spaceflight, but few have compared the impact of various lengths of spaceflight missions on the characteristics of microbes. Researchers generally agree that microgravity (MG) is the most critical factor influencing microbial physiology in space capsules during flight missions. This study compared the growth behavior and transcriptome profile of Proteus mirabilis cells exposed to long-term simulated microgravity (SMG) with those exposed to short-term SMG. The results showed that long-term SMG decreased the growth rate, depressed biofilm formation ability, and affected several transcriptomic profiles, including stress response, membrane transportation, metal ion transportation, biological adhesion, carbohydrate metabolism, and lipid metabolism in contrast to short-term SMG. This study improved the understanding of long-term versus short-term SMG effects on P. mirabilis behavior and provided relevant references for analyzing the influence of P. mirabilis on astronaut health during spaceflights.

Microscale Modeling of Particle Impact on Thermal Protection System Materials During High-Speed Entry

Micron-sized particles suspended in planetary atmospheres can damage thermal protection systems (TPS) during entry of space capsules into planetary bodies. TPS materials are complex heterogeneous carbon composites, where the microstructure of the composite can play a pivotal role in the propagation of damage caused by the impact. Here, we present the application of a novel computational technique called the lattice particle method to understand the initiation and growth of craters formed on TPS materials upon impact by particles. The simulations are initially compared against experiments that used borosilicate as the impacting particle and fused silica as the target surface. The simulations reproduce the damage profiles, diameters, and depths of the craters being formed on the target silica surface. A parametric study is then performed by varying the fracture strength of the target surface and the impacting particle. It is found that the profiles of the damaged region on the silica surface primarily depend on the fracture strength of the silica surface, and not the impacting particle. The simulations are extended to model the damage of porous carbon composites that are used as TPS materials. Microstructures of carbon composites are generated using an in-house code that has been shown to reproduce features of the real material in past studies. While the crater depth on the fused silica surface was within 38% irrespective of the fracture strength of the particle, the damaged depth changes by at least an order of magnitude when a carbon composite surface is used and the fracture strength of the impacting particle is varied. Finally, the influence of damage on the effective permeability is computed using the direct simulation Monte Carlo technique. The maximum increase in the permeability force for the damaged microstructures is found to be 22%, which is within the statistical variability of the material properties observed for the TPS material that is under investigation.

Investigation of vortical structures in the wake of pseudo-random roughness surfaces in hypersonic reacting boundary-layer flows

The influence of roughness on the laminar-turbulent transition of hypersonic flows is investigated with Direct Numerical Simulations (DNS) in a re-entry scenario of an Apollo-like space capsule. A Mach 20 flow regime is simulated for conditions at an altitude of 57.5 km. This study uses two different generating shapes (sinusoidal and triangular shaped waves) for random distributed patches. Stronger streamwise vorticity is observed for most configurations with the triangular base functions. The simulation includes the chemical equilibrium gas model. Vortical structures in the wake of both roughness patch types interact with an acoustic perturbation derived from local one-dimensional inviscid (LODI) relations. A breakdown of the cross-flow-like vortex in the wake of the roughness patch is observed for both roughness patches. The growth of modal instabilities is studied with a spatio-temporal Fourier analysis. Both y- and z-type instabilities, which are present in cross-flow vortices at low speeds, are observed for the sinusoidal patch. In the triangular configuration, the y-type instability is the dominating instability which is in line with the stronger wall-normal velocity gradients caused by the increase in spanwise slope of the patch.

Effective Permeability of Carbon Composites Under Reentry Conditions

Effective permeability of a porous carbon composite used as thermal protection system on space capsules is computed using the direct simulation Monte Carlo technique. The microstructure of the carbon composite is synthetically generated using an in-house code. Permeabilities obtained using synthetic microstructures of the precursor (carbon fibers) are compared with two independent experimental dataset, and good agreement is observed. It is conclusively shown that the difference in permeability values between the two experimental datasets arose from the variations in the sample density. An approach to digitally infuse resin into the precursor is proposed. Comparison of the permeability for the full composite (carbon fibers with resin) with experimental data resulted in errors within 7.5%, indicating that representative microstructures generated digitally can be used to compute and predict effective permeability of porous carbon composites. Simulations of Ar and air permeating through the full composite are performed, and an intrinsic material permeability () of and a Klinkenberg constant () of that is only dependent on the temperature and the molecular weight of the gaseous species are obtained. It is shown that this new generalized relation could be used for other gases such as CO and .

On Demand Electrochemical Peroxide Generation for Disinfection

Novel technologies with limited earth support are required to enable habitation in microgravity spacecraft habitats such as International space station (ISS). One area of particular need for the interstellar travel community is cleaning/sanitizing supplies to meet personal hygiene requirements, which is currently accomplished through the use of pre-packaged, disposable, wetted wipes. These items represent an appreciable carry-along mass and disposal/replacement burden requiring ground support. Therefore, a system is desired that could utilize onboard utilities to create disinfecting solutions to eliminate storage/disposable problems of the wetted wipes and further reduce the astronaut’s dependence on earth-based supplies.Faraday Technology Inc. is addressing this challenge by demonstrating an electrochemical technology which utilizes on-board supplies of air and water for on demand generation of hydrogen peroxide. This concept is based on the electrochemical reduction of oxygen to hydrogen peroxide by two electron transfer reactions which proceeds as [O2 + 2H+ + 2e- → H2O2 or O2 + 2H2O + 2e- → H2O2 + 2OH-][i]. Hydrogen peroxide is well-established disinfectant with non-toxic decomposition products (viz., O2 and H2O), that is safe enough for human contact to be sold commercially as a 1-5 w/w% solution, which makes it an ideal disinfecting solution for closed space environments.Previously, Faraday has demonstrated electrochemical generation of 3 w/w% hydrogen peroxide in a ‘H-cell’ electrochemical laboratory set-up utilizing a sodium sulfate electrolyte[ii]. Following on, Faraday designed and constructed an electrochemical sub-scale reactor for generating >1 w/w% hydrogen peroxide in RO water enabled by ion conductive resin[iii]. The next step was to understand the effects of zero-gravity on the hydrogen peroxide reactor. The electrochemical reactor and components were assembled in a zero-gravity test setup. Optimized conditions from ground-based performance data were implemented during the zero-gravity flight test. The flight tests indicated there were no adverse effects of zero-gravity on the performance of the hydrogen peroxide generation system vis-à-vis ground operation[iv]. In order to facilitate use of low conductive DI water stream available aboard the International Space Station (ISS), Faraday modified the reactor design by utilizing anion exchange membrane (AEM) within the sub-scale reactor, which reduced flooding and improved reactor stability (Figure 1)[v]. The modified sub-scale reactor was used to demonstrate the potential of generating >2 w/w% hydrogen peroxide in very low conductivity electrolytes such as DI and pure oxygen. On-going activities at Faraday are defining the effects of capsule air and contaminants in the DI water on performance of the sub-scale reactor. The system is also being scaled to deliver 1L of ~2% w/w% hydrogen peroxide for disinfectant applications from DI water feed-stream with air as a feed source[v]. This system eliminates the need to ferry disinfectant wipes to manned space capsules and is a critical enabling technology for future moon-based missions and beyond. Acknowledgements: Financial support of NASA Contracts NNX16CA43P, NNX17CJ12C, and 80NSSC20C0070 is acknowledged.

Can the Biophilia Hypothesis Be Applied to Long-Duration Human Space Flight? A Mini-Review.

The International Space Station (ISS) has around 3–5 crew members on-board at all times, and they normally stay on the ISS for about 5–7months in duration. Since March 2020, 170 long-duration space missions have occurred on the ISS. Thus, long-duration space missions are an integral part of space exploration and will only continue to expand in duration as missions to the Moon and Mars are on the horizon. However, long-duration space missions present several challenges to human crew members. Most of these challenges have been associated with physiological adaptation to microgravity, including motion sickness, muscle atrophy, and cardiovascular deconditioning. While not as well-studied, another major factor to consider when planning long-duration space missions is the psychological impact of the environment on the astronauts. Astronauts living in space will be unable to access natural landscapes and other environments found to have restorative effects on psychological stress and overall well-being. On top of being unable to access these restorative natural environments, astronauts will also be exposed to the stressful, unfamiliar environment of space. The purpose of this mini-review is to first summarize the literature related to stressors associated with space. Next, an overview of the large breadth of literature on the biophilia hypothesis and restorative environments will be provided, as these may serve as relatively simple and cost-effective solutions to mitigate the stress faced during long-duration space missions. Lastly, considerations related to the design of such environments in a space capsule as well as future directions will be presented.

Biodynamic human body model to assess the injury risk during space capsule landing

The present study proposes a 15-degrees of freedom multibody model of semi-supine humans to estimate the injury risk to a space capsule occupant during landing. The model consists of five body segments representing head-neck, thorax-arms, abdomen, thigh-pelvis, and leg. The semi-supine human model is calibrated using transmissibility responses of each body segment obtained from parallel vibration testing on the human subjects. The occupants' dynamic response to impact acceleration incurred during landing is simulated through the developed model. The model estimated the highest acceleration at the thorax and head, respectively, in the chest and spine directions. The impact acceleration of 20g is observed to violate the low injury risk criterion at the seat angle of 30°. The proposed human body model can be employed to design and test the effectiveness of attenuation and restraint systems of a space capsule.

Temporal Characteristics of the Oropharyngeal and Nasal Microbiota Structure in Crewmembers Stayed 180 Days in the Controlled Ecological Life Support System.

Confined experiments are carried out to simulate the closed environment of space capsule on the ground. The Chinese Controlled Ecological Life Support System (CELSS) is designed including a closed-loop system supporting 4 healthy volunteers surviving for 180 days, and we aim to reveal the temporal characteristics of the oropharyngeal and nasal microbiota structure in crewmembers stayed 180 days in the CELSS, so as to accumulate the information about microbiota balance associated with respiratory health for estimating health risk in future spaceflight. We investigated the distribution of microorganisms and their dynamic characteristics in the nasal cavity and oropharynx of occupants with prolonged confinement. Based on the 16S rDNA v3–v4 regions using Illumina high-throughput sequencing technology, the oropharyngeal and nasal microbiota were monitored at eight time points during confinement. There were significant differences between oropharyngeal and nasal microbiota, and there were also individual differences among the same site of different volunteers. Analysis on the structure of the microbiota showed that, in the phylum taxon, the nasal bacteria mainly belonged to Actinobacteria, Firmicutes, Proteobacteria, Bacteroidetes, etc. In addition to the above phyla, in oropharyngeal bacteria Fusobacterial accounted for a relatively high proportion. In the genus taxon, the nasal and oropharyngeal bacteria were independent. Corynebacterium and Staphylococcus were dominant in nasal cavity, and Corynebacterium, Streptococcus, and Neisseria were dominant in oropharynx. With the extension of the confinement time, the abundance of Staphylococcus in the nasal cavity and Neisseria in the oropharynx increased, and the index Chao fluctuated greatly from 30 to 90 days after the volunteers entered the CELSS.Conclusion: The structure and diversity of the nasal and oropharyngeal microbiota changed in the CELSS, and there was the phenomenon of migration between occupants, suggesting that the microbiota structure and health of the respiratory tract could be affected by living in a closed environment for a long time.

ROpenPose: A Rapider OpenPose Model for Astronaut Operation Attitude Detection

This article proposes a rapider OpenPose model (ROpenPose) to solve the posture detection problem of astronauts in a space capsule in a weightless environment. The ROpenPose model has three innovations as follows: 1) It uses MobileNets instead of VGG-19 to achieve lighter calculations while ensuring the accuracy of model recognition. 2) Three small convolution kernels replace the large convolution kernel of the original OpenPose, which significantly reduces the computational complexity of the model. 3) Through the parameter sharing of a convolution process, the original two-branch structure is changed to a single-branch structure, which obviously improves the calculation speed of the model. A residual network is proposed to suppress the hidden danger of gradient disappearance. The deployment of ROpenPose greatly improves astronauts’ detection efficiency while ensuring their high detection performance, and thereby realizing the real-time monitoring of their operation attitude. Experimental results show that ROpenPose runs at speed higher than and detection performance comparable to a number of the existing state-of-the-art models.

An Improved Capsule Network Based on Capsule Filter Routing

Capsule network (CapsNet) is a novel type of network that can retain spatial information, because each capsule can integrate more information than scalar-output features. However, the CapsNet learns all the features in the input image due to the lack of pooling operation, and there is no connection between different layers in the multi-layer network structure. In this paper, we propose an improved capsule network (CapsNet) based on Capsule Filter Routing (CFR) to address this problem, namely CFR-CapsNet. Firstly, we propose a new routing method called CFR for filtering capsules based on capsule activation values, which can speed up the operation of the model, and then introduce a self-attention mechanism to improve the performance of the primary capsule in the capsule space. Furthermore, in the multi-layer network structure, we transmit the information of the classified capsule with the largest activation value in the previous capsule layer to the primary capsules of the next layer, which improves the relevance of the overall structure. We conduct experiments on Fashion-MNIST, SVHN, and CIFAR-10/100, and the experimental results show that our method can improve the performance of the CapsNet more effectively than other state-of-the-arts.

The Biological Survival Rule, Biosphere 2 and the Mars Ecological Engineering Project

In this paper, the biological survival rule is described, based on which the cause of the failure of Biosphere 2 is analysed at the structural level to find solutions to the existing problems and guide biological practices in the future. The main cause of the failure of Biosphere 2 was that species were not introduced in classes, in order and in a step-by-step manner and not in sufficient time. A solution for establishing a biosphere involves step-wisely introducing species in the following order: prokaryotes, eukaryotes, plants, animals, and humans. The future Mars ecological engineering project should also adopt the above rule and follow the biological survival rule, starting from introducing prokaryotes and then simple eukaryotes to reproduce the process of biological evolution on Earth, which can also be applied to Lunar bases and space capsules.

A Navigation and Pressure Monitoring System Toward Autonomous Wireless Capsule Endoscopy

Continuous navigation information for medical insertion methods including wireless capsule endoscopy is an important feature to guide a medical instrument/object to the targeted location within a hollow organ or internal cavity of the patient in the best possible way. Also, an autonomous medical insertion or swallowable device with a self-contained navigation system would reduce the role of the high-level operator and hence reduce the human-factor mistake and risk of injury. The navigation techniques suggested for Wireless Capsule Endoscopy are image-based that are required to transfer and process a significant amount of data in real-time operation. This would increase the complexity of the system and would be more difficult in dark or liquid environments. A novel navigation system for Wireless Capsule Endoscopy/ordinary endoscopy that does not depend on any external source for operation and can handle the uncertainties of the path even in a dark or liquid environment ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i.e</i> .mucosa) of the human body is presented in this paper. The key element of the system is based on a capacitive-based pressure sensor array mounted on the capsule with the shape of semi-hemisphere. The place of each node is arranged to represent the variation in the latitude and the longitude of the travelling path. The system can acquire the required information to navigate the capsule in three-dimensional space and enhance the safety of the locomotion by monitoring the pressure between the capsule and the ambient environment. The system determines the variation of the path 180° in longitude and latitude with less than (<0.004%) percentage of error. Working algorithms for flexible and rigid environments are described in this paper.

Influence of non-equilibrium reactions on the optimization of aerothrust aeroassisted maneuver with orbital change

The spaceplane is perspective vehicle due to wide maneuverability in comparison with a space capsule. Its maneuverability is expressed by the larger flight range and also by a possibility to rotate orbital inclination in the atmosphere by the aerodynamic and thrust forces. Orbital plane atmospheric rotation maneuvers can significantly reduce fuel costs compared to rocket-dynamic non-coplanar maneuver. However, this maneuver occurs at Mach numbers about 25, and such velocities lead to non-equilibrium chemical reactions in the shock wave. Such reactions change a physicochemical air property, and it affects aerodynamic coefficients. This paper investigates the influence of non-equilibrium reactions on the aerothrust aeroassisted maneuver with orbital change. The approach is to solve an optimization problem using the differential evolution algorithm with a temperature limitation. The spaceplane aerodynamic coefficients are determined by the numerical solution of the Reynolds-averaged Navier-Stokes equations. The aerodynamic calculations are conducted for the cases of perfect and non-equilibrium gases. A comparison of optimal trajectories, control laws, and fuel costs is made between models of perfect and non-equilibrium gases. The effect of a chemically reacting gas on the finite parameters is also evaluated using control laws obtained for a perfect gas.