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Open Access journal Space: Science & Technology, published in association with BIT, promotes the interplay of science and technology for the benefit of all application domains of space activities. It particularly welcomes articles illustrating successful synergies in space programs and missions.
Space: Science & Technology’s editorial board is led by Peijian Ye (China Academy of Space Technology), and it includes experts who have been carefully selected to include all domains of sciences and technologies covered by space missions of different types.
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Space Habitat Astronautics: Multicolour Lighting Psychology in a 7-Day Simulated Habitat
During space missions, astronauts live in a confined technological environment, completely isolated and deprived of the variety and variation found in the environment on Earth. This circumstance has a strong impact on the psycho-physiological states of the crew. Particularly in light of the plans for long-duration missions, new research needs to be carried out. The goal of this study, conducted at Xiangtan Central Hospital in China, was to test whether multicolour lighting can improve people’s psychological state in an isolated and confined environment over a period of seven days. Twenty participants (10 male and 10 female) were randomly divided into two groups: one group that was exposed to multicolour lighting and a control group, which was exposed to a static, monotonous white interior. The participants’ psychological state was recorded on the first day, the fourth day, and the seventh day. The results of the control group showed that the participants’ negative emotions and anxiety continued to increase over time, whereas the group randomly exposed to multicolour lighting that changed every three hours did not show any significant increase in negative emotions and anxiety. Moreover, the random change of light colour in the isolated environment appeared to help the participants increase their sense of surprise, thereby counteracting monotony. Finally, during this experiment, it was observed that when people who are accustomed to being connected to social networks were deprived of this, they experienced insomnia and unaccustomed reactions, in particular on the first days of deprivation. This article contributes to future space exploration and to social and psychological support of life in isolated and confined environments.
Generalized Maximum Correntropy Kalman Filter for Target Tracking in TianGong-2 Space Laboratory
Target tracking plays an important role in the construction, operation, and maintenance of the space station by the robot, which puts forward high requirements on the accuracy of target tracking. However, the special space environment may cause complex non-Gaussian noise in target tracking data. And the performance of traditional Kalman Filter will deteriorate seriously when the error signals are non-Gaussian, which may lead to mission failure. In the paper, a novel Kalman Filter algorithm with Generalized Maximum Correntropy Criterion (GMCKF) is proposed to improve the tracking accuracy with non-Gaussian noise. The GMCKF algorithm, which replaces the default Gaussian kernel with the generalized Gaussian density function as kernel, can adapt to multi-type non-Gaussian noises and evaluate the noise accurately. A parameter automatic selection algorithm is proposed to determine the shape parameter of GMCKF algorithm, which helps the GMCKF algorithm achieve better performance for complex non-Gaussian noise. The performance of the proposed algorithm has been evaluated by simulations and the ground experiments. Then, the algorithm has been applied in the maintenance experiments in TianGong-2 space laboratory of China. The results validated the feasibility of the proposed method with the target tracking precision improved significantly in complex non-Gaussian environment.
Study on Dynamic Characteristics of Mars Entry Module in Transonic and Supersonic Speeds
The aerodynamic configuration of the Tianwen-1 Mars entry module that adopts a blunt-nosed and short body shape has obvious dynamic instability from transonic to supersonic speeds, which may bring risk to parachute deployment. The unsteady detached eddy of the entry module cannot be accurately simulated by the Reynolds-Averaged Navier-Stokes (RANS) model, while the computational cost for direct numerical simulation (DNS) and large eddy simulation (LES) is huge. It is difficult to implement these methods in the coupled engineering calculation of unsteady flow and motion. This paper proposes the integrated numerical simulation method of computational fluid dynamics and rigid body dynamics (CFD/RBD) based on detached eddy simulation (DES) and calculates and studies the dynamic characteristics of attitude oscillation of the Mars entry module in free flight from transonic to supersonic speeds with one degree of freedom (1-DOF) at small releasing angle of attack. In addition, the unstable range of Mach number and angle of attack are determined, and the effect of different afterbody shapes on dynamic stability is analyzed.
Analysis and Verification of Aerodynamic Characteristics of Tianwen-1 Mars Parachute
The Mars parachute flight environment is supersonic, low-density, and low dynamic pressures. To ensure the operating performance and reliability, the design optimization and verification of the Tianwen-1 Mars parachute have been carried out. Firstly, through supersonic and subsonic wind tunnel tests, the design optimization of the parachute structure is realized. Subsequently, the high-altitude flight tests of four parachutes were conducted, the drag coefficient and the oscillation angle of the parachute from supersonic to subsonic speed were gained, and the aerodynamic characteristics and reliable opening of the parachutes were thoroughly tested and verified. This article presents the design, development, and qualification of the Tianwen-1 Mars parachute, which can provide a reference for the creation of future Mars exploration parachutes.
A Review on the Development of Spaceborne Membrane Antennas
The membrane antenna technology is a very promising approach to obtain large aperture with light weight and low stowed volume. In the past decades, extensive studies have been carried out on active and passive membrane antennas. However, the practical spaceborne applications are rare due to many challenges, e.g., the surface accuracy maintenance, the on-orbit reliability, and the environmental compatibility. This paper summarizes the history and state-of-art progresses on spaceborne membrane antennas. Curved surface reflectors, conformal active membrane antennas, planar array membrane antennas, and planar reflectarray membrane antennas have been introduced, respectively. Radiofrequency design, deploying mechanism, material, experiment, application, and analysis method have been presented. By concluding the advantages and challenges of the current membrane antennas, this paper is aimed at providing a perspective of the existing problems and future trend of spaceborne membrane antennas.
Unsupervised Spectrum Anomaly Detection Method for Unauthorized Bands
With the rapid development of wireless communication, spectrum plays increasingly important role in both military and civilian fields. Spectrum anomaly detection aims at detecting emerging anomaly signals and spectrum usage behavior in the environment, which is indispensable to secure safety and improve spectrum efficiency. However, spectrum anomaly detection faces many difficulties, especially for unauthorized frequency bands. In unauthorized bands, the composition of spectrum is complex and the anomaly usage patterns are unknown in prior. In this paper, a Variational Autoencoder- (VAE-) based method is proposed for spectrum anomaly detection in unauthorized bands. First of all, we theoretically prove that the anomalies in unauthorized bands will introduce Background Noise Enhancement (BNE) effect and Anomaly Signal Disappearance (ASD) effects after VAE reconstruction. Then, we introduce a novel anomaly metric termed as percentile (PER) score, which focuses on capturing the distribution variation of reconstruction error caused by ASD and BNE. In order to verify the effectiveness of our method, we developed an ISM Anomaly Detection (IAD) dataset. The proposed PER score achieves superior performance against different type of anomalies. For QPSK type anomaly, our method increases the recall rate from 80% to 93% while keeping a false alarm rate of 5%. The proposed method is beneficial to broadband spectrum sensing and massive spectrum data processing. The code will be released at :QXSLAB/vae_ism_ano.git.