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This article presents a trajectory design problem concerning the exploration of potentially hazardous near-Earth asteroids (PHAs) with reusable probes from cislunar space. A total of 20 probes, making round trips departing from and returning to a service space station in a lunar distant retrograde orbit, are expected to explore as many PHAs as possible by means of close flyby within a 10-year time window. The trajectory design problem was released in the 12th edition of China's Trajectory Optimization Competition on 20 August 2022, and a total of 10 sets of trajectory solutions were submitted. As the authors who proposed the competition problem, we present in this article the problem descriptions, trajectory analysis, and design, as well as an impressive trajectory solution in which a total of 105 PHAs are explored. It is concluded that taking advantage of reusable probes from cislunar space is a promising option to efficiently explore large numbers of PHAs. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of Nanjing University of Aeronautics & Astronautics is the property of Editorial Department of Journal of Nanjing University of Aeronautics & Astronautics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Space manipulators are important for the assembly, construction, operation, and maintenance of space stations. To ensure that the manipulator system on the China Space Station (CSS) is user-friendly, the human factors engineering team has carried out extensive studies on the human factors design and evaluation of the space manipulator teleoperation system from three aspects: the technical process, research on ergonomic requirements, and ergonomic evaluation. This article systematically combs the technical process and index system of the human factors design and requirements research on CSS manipulator teleoperation system, which has guided the optimization of space manipulator engineering. This article expounds the research work on ergonomic requirements and suggestions related to manipulator teleoperation through experimental research on cognitive characteristics and human factors in display and control interfaces. We focus on human factors experimental research for camera type and handle polarity, and a recommended scheme for camera display and handle polarity has been screened out accordingly. Finally, the human-in-the-loop ergonomic evaluation method is demonstrated with a cooperative manual control task. The research results have facilitated the human factors design and optimization improvement of the space manipulator manipulator system, and have contributed significantly to the safe and smooth completion of astronaut extravehicular activities on the CSS. [ABSTRACT FROM AUTHOR]

Extravehicular activity (EVA) is a key point and a difficult point for manned spaceflight tasks, as well as an inevitable trend in the development of the manned spaceflight industry. Equipment maintenance, load installation, and extravehicular routing inspection via EVA on the track are necessary to guarantee the safety and reliability of the long-term in-orbit operation of the China Space Station. In this paper, a comprehensive analysis was conducted on the features of multiple tasks, diverse working modes, and strong systematic coupling during the EVA of the China Space Station (CSS). On this basis, the design, implementation technologies' development, and in-orbit performance evaluation during EVA were expounded. In the space station system, an extravehicular reliability verification and evaluation system suitable for the requirement for EVA under the conditions of China's multi-mission, multi-module combination, and repairable spacecraft was constructed. Finally, the in-orbit EVA implementation of the China Space Station since the launch of the core module to the present was summarized, and the subsequent application of the extravehicular technologies in manned lunar landing projects and optical modules was anticipated. [ABSTRACT FROM AUTHOR]

The plasma in situ detector is a multi-sensor package designed to in situ measure the bulk parameters of the local ionospheric plasma. The plasma in situ detector is comprised of three sensors: Langmuir probe (LP), retarding potential analyzer (RPA) and ion drift meter (IDM). LP measures electron density and temperature. RPA measures ion density, temperature and ion horizontal velocity. IDM measures the transverse horizontal component of the ram velocity. The plasma in situ detector has been installed outside the wentian module cabin, and the boom has been successfully deployed which extends the spherical sensor of LP beyond the sheath of the cabin. RPA and IDM were installed at the front of the experiment package, with the horizontal axis direction along the forward flight direction of the space station. This paper discusses the general performance characteristics of the in situ detector, the functional performance of each sensor, and initial results of some classical ionospheric features being observed. [ABSTRACT FROM AUTHOR]

The effects of the response characteristics of the Fengyun-4A Lightning Mapping Imager (LMI) on its detection capability were studied using the raw event data of LMI in 2020. The simultaneous observation data of the Lightning Imaging Sensor (LIS) on the International Space Station (ISS) were used to evaluate the LMI detection capability. The results reveal that the minimum detectable radiance of lightning events in the 16 subregions of LMI has shown regional differences, with the southern subregions lower than the northern subregions, indicating that the southern ones are more conducive to the identification of events. The diurnal variation of the detectable event radiance in all subregions presents the main peak around noon, which comes from the influence of the bright background and varies largely in different subregions depending on the subregions' response capability. The overall high values and regional differences of flash properties observed by LMI also show strong correlation with the variation of the minimum detectable radiance of events. Moreover, it is found that the southwest subregions have the highest coincidence ratio (CR) with ISS LIS, followed by the southeast subregions and the northeast subregions, and the northwest subregions have the lowest CR, which is closely related to the response of each subregion. The LIS flashes that can be detected by LMI are brighter, larger, and last longer compared to the total LIS flashes. The findings in this study will help explain the inconsistency of the LMI detection capability and promote the LMI data processing associated with pixel energy distribution. Significance Statement: The Fengyun-4A (FY-4A) Lightning Mapping Imager (LMI) is the first geostationary satellite-borne lightning imager developed in China, which has the ability to continuously observe lightning within a large field of view. However, in the application of the data, it was found that the detection capability of the LMI differed significantly in different regions and exhibited diurnal variations, which may be related to the response characteristics of the LMI detector. This study reveals the effect of the response characteristics of the LMI detector on its detection results. The findings will help improve the usability of LMI data and improve the processing of these data to adjust the observation inconsistency. [ABSTRACT FROM AUTHOR]

The Chinese Space Station Telescope (CSST) is the first space optical survey telescope of China. It will perform scientific observations and yield important scientific results, e.g. multi-color photometry to find and characterize exoplanets. The precision of time-domain photometry affected by various astrophysical and instrument noises is crucial for exoplanet detection and characterization. This paper constructs a time-domain model to simulate the stellar signal and various noises based on the main technical parameters of CSST published so far. The precision of photometry is analyzed by modeling the signal and noises for an example of the gazing mode in the i-band. We investigate and discuss the contribution of various noise sources in aperture photometry, especially the jitter noise caused by pointing jitter and pixel response inhomogeneity. The test results also provide the recommended aperture sizes for photometry. Jitter noise can be suppressed by reducing jitter amplitude, uniforming pixels, or using differential photometry with reference stars. Our simulation results have broad applications, including precision predictions for time-domain photometry, the refinement of CSST instrumental specifications, the evaluation of exoplanet detection capabilities, and improvements in data reduction progress for CSST. [ABSTRACT FROM AUTHOR]

In terms of cataloged debris produced, the anti-satellite test carried out by Russia, in November 2021, at an altitude of about 480 km, leading to the destruction of the old satellite Cosmos 1408, was the second worst to date and represented the third worst fragmentation in orbit. It generated more than 1/4 of the cataloged debris produced over 55 years by all such tests and almost twice as many as were produced by all previous Soviet tests. After placing this event in its historical context, this paper analyzes in detail how the evolution of the Cosmos 1408 debris cloud affected the environment below 600 km in the first seven months, focusing on the two operational space stations and the Starlink large constellation of satellites. During the first six months following the test, the Cosmos 1408 cloud of fragments nearly doubled the average flux of cataloged objects on the International Space Station and increased by about 3/4 that on China's Tiangong. In the same period, the Starlink large constellation saw an average increase in the flux of cataloged objects of about 20%. Some orbital planes, the "counter-rotating" ones with respect to the Cosmos 1408 debris cloud, were more affected than others, and the affected planes gradually changed over time, due to the differential precession of cloud and constellation nodes. However, being the Starlink constellation 70 km higher up, the flux of Cosmos 1408 cataloged debris steadily decreased over the period analyzed, due to the cloud orbital decay, reducing to just over a quarter of its extrapolated initial value after seven months. • A review of ASAT tests as a source of orbital debris was presented. • The impact of the Cosmos 1408 destruction was put into context. • The cataloged debris flux increase on space stations was computed and discussed. • The debris flux increase and evolution on Starlink orbit planes was analyzed. • A moratorium on this type of ASAT tests was recommended, including low LEO. [ABSTRACT FROM AUTHOR]

There are many kinds of microorganisms that inhabit the environment of manned space stations. Wet wipes are a common tool used in space stations to clean and reduce microorganisms on surfaces. Here, we compared the performance of five types of wipes used by the Chinese Space Station (CSS) on orbit before 2021 in terms of microbial decontamination. In previous studies, we found that Bacillus sp. TJ-1-1 and Staphylococcus sp. HN-5 were the most abundant microorganisms in the assembly environment of the CSS. In this study, we used these two bacteria to build different microbial load models to represent the occurrence and non-occurrence of microbial outbreaks in the on-orbit CSS. The results show that the number of microorganisms that can be removed when wiping the surface with high microbial load by wet wipes was higher than that when wiping the surface with low microbial load. For on-orbit daily cleaning and keeping the microbial population within the regulation concentration range, it is suitable to use two pure water wipes per 100 cm2. When the number of microorganisms increases to a degree where astronauts can see the colonies with their naked eyes, the best way to eliminate the problem is to wipe them thoroughly and repeatedly with at least four quaternary ammonium–based wipes every 100 cm2. [ABSTRACT FROM AUTHOR]

Objectives: With the ultra-high precision time and frequency signals provided by space high precision time and frequency system, series of space-to-ground time and frequency transfer and fundamental physics experiments can be carried out to support high precision validation of relativity and related theories. Methods: First, theoretical derivation and simulation analysis are conducted on the time and frequency transfer algorithm of space laser links. Theoretical formula of space-to-ground laser two way time transfer are reviewed, and the advantages and disadvantages of X-type and Lambda-type approaches are compared and analyzed. Then, the impact of relativistic effects on the conversion between proper time and coordinate time is discussed for the specific orbital height of China space station. Finally, the impact of space-to ground time and frequency transfer discontinuity on the stability evaluation of high-precision atomic clocks onboard space stations is discussed. Results: The results show that: (1) Lambda-type two-way time transfer based on satellite laser ranging can make up the distance difference of first-order Doppler effect on the uplink and downlink, and increase of Sagnac effect can be ignored. (2) The relativistic effect of the conversion between proper time and coordinate time for satellite ground time transfer makes high demands on the velocity accuracy of space station positions, in order to achieve 1×10-18 frequency transfer accuracy, geocentric distance accuracy of 1 dm and speed accuracy of 0.1 mm/s of space station is required; (3) Influenced by the visibility of space stations to the ground, it is not possible to evaluate the medium term stability of atomic clocks with only the observation data of domestic stations satellite for space-to-ground links. Conclusions: High precision navigation solution is important to ensure high-precision time and frequency transfer between space and ground. How to optimize navigation algorithms and use various payloads onboard to achieve high-precision position and velocity solution is a key issue that needs to be studied. [ABSTRACT FROM AUTHOR]

Copyright of Telecommunication Engineering is the property of Telecommunication Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Methods for fault diagnosis based on metric learning, in which a query sample is classified by picking the closest prototype from the support set based on their feature similarities, have been the subject of many studies. In real-world applications of in-orbit products, such as circulating pumps, the computation of similarity between different pairs is prone to different degrees of inaccuracy, especially epistemic uncertainty. Knowing and considering the uncertainty of similarity may improve fault detection accuracy. This article provides a unique approach to fault diagnosis based on Prototypical Network (Pro-Net) and Uncertainty Theory. In particular, we use epistemic uncertainty by altering the representation of prototypes from a deterministic scalar to an uncertain representation. To assess the similarity between a query and the prototypes in a support set, we calculate the uncertain distance between the pairs using cross-entropy. Experiments with symmetrical structures reveal that our proposed method significantly enhances classification precision and achieves state-of-the-art performance. It improves the reliability of fault diagnosis and reduces the risk of making erroneous judgments in safety-critical systems, decreasing the possibility of adverse consequences. [ABSTRACT FROM AUTHOR]

This article compares two central pillars of China's space programme and observes that Chinese space diplomacy is not uniform regarding international scientific co-operation either in its approaches or in results. In the case of the Chinese Space Station programme, the China National Space Administration went through existing United Nations (UN) channels and successfully attracted international partners. However, the International Lunar Research Station has avoided UN channels and used national and bilateral platforms. This bifurcation in approaches and results offers an intriguing puzzle concerning international co-operation: practices of institutionalised multilateral co-operation and areas of state-centric bilateral co-operation co-exist in this case and further complicate the issue of space diplomacy. To propose a potential explanation, it is argued here that a crucial intermediate variable — institutional density — requires further theorising, as it seems to influence strategic choices about space diplomacy, which may lead to success or failure. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Beijing University of Civil Engineering & Architecture is the property of Journal of Beijing University of Civil Engineering & Architecture Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Telecommunication Engineering is the property of Telecommunication Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Backward Limb Spectrometer (BLS) onboard the Tiangong-2 (TG-2) space laboratory, the first spaceborne limb sounding instrument of China, was successfully launched on 15 September 2016, and its measurements of scattered photons of sunlight along the limb line-of-sight (LOS) in the 290–1000 nm range could be used to derive the vertical distribution of stratospheric ozone with high vertical resolution. Ozone profiles with a vertical resolution of one km in 10–40 km and 30–50 km were retrieved by the triplet and pair methods, respectively, and the ozone profiles retrieved by the BLS were compared with the ozone sounding data over four sounding stations. Meanwhile, the Ozone Mapping and Profiler Suite Limb Profiler (OMPS/LP) version 2.5 (v2.5) stratospheric ozone profile product was also introduced for comparison. The retrieval results showed a good agreement with the ozone profiles of ozone sounding and the OMPS/LP v2.5 product, and the differences were basically within 25% above 20 km, while relatively larger differences occasionally occurred below 20 km. The case studies over four sites worldwide demonstrate that the BLS is capable of measuring stratospheric ozone profiles with high vertical resolution. [ABSTRACT FROM AUTHOR]

The article focuses on China's ambitious 2050 space plan which include establishing a lunar research station, launching a Venus atmosphere sample-return mission, and conducting over 30 space science missions.

The greatest challenge of electrostatic levitation for containerless material processing is the stable control of charged material during heating. Recently, high-precision self-adaptive control of electrostatic levitation has been achieved in China's Space Station. Based on the 1D and 3D co-simulation analysis, an optimal scheduling of control strategies of sample release and retrieval in space is developed. Both simulation results and on-orbit experiments demonstrated that the inversion of surface charge is responsible for the heating induced material instability. On-orbit experiments indicated that under laser illuminations, the net surface charge of metal Zr changed from positive to negative at 900 K and from negative to positive at 1300 K. The possible physical mechanism of the charge inversion of heated material is discussed. [ABSTRACT FROM AUTHOR]

Objectives: Gravitational redshift test using high precision space-borne/sattelite-payload atomic clocks is always a hot topic in physics. With the improvement of the accuracy of atomic clocks, it is possible to use high-precision time-frequency signals to test the gravitational redshift and determine the gravitational potential. Methods: The experiment module of China space station (CSS) is expected in orbit in October 2022, which lays a foundation for high-precision gravitational redshift experiment. The dual-frequency combination method is applied to eliminate the propagation frequency shifts by using an uplink and a downlink with the same frequency and different polarization direction. The gravitational redshift simulation experiment is carried out by using the microwave links of CSS time-frequency comparison system. Results: The results show that the stability of atomic clock achieves 2 × 10−15 / τ, the long term stability reaches 10−18, and the accuracy of gravitational redshift reaches 10−7 .Conclusions: It is 1− 2 orders of magnitude higher than the highest accuracy of gravitational redshift in the world. [ABSTRACT FROM AUTHOR]

Copyright of URVIO - Revista Latinoamericana de Seguridad Ciudadana is the property of FLACSO - Ecuador (Facultad Latinoamericana de Ciencias Sociales) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This article endeavors to understand the construction of a geopolitical imaginary over the People's Republic of China deep space station on Bajada del Agrio, Province of Neuquén, from the perspective of geopolitics. This paper introduces a comparative perspective: the Chinese space facilities are not a unique case within the borders of this sovereign state: there is a similar space installation called Deep Space Antenna under European Union flag in Malargüe, Province of Mendoza. In order to track the construction of such geopolitical imagination, this article analyzes the discourses offered in newspapers of national circulation in the South American country: Clarín, La Nación, and Página/12 from 2007 to 2016. This work also describes and analyzes domestic and foreign political discourses, and the sources of information the media selects to explain the issues the facilities raise. Argentina is a state of the Global South with an autonomous track of space development. Acquiring technology from a rising power could be disruptive, generating tensions with the core states, which were former exclusive partners and clients. [ABSTRACT FROM AUTHOR]

China has been excluded from participation in the International Space Station (ISS) since 2011. The exclusion was codified into law by the Wolf Amendment (2011), which was passed in Congress to restrict extensively, based on financial constraints, the National Aeronautics and Space Administration (NASA) and the Office of Science and Technology Policy (OSTP) from cooperating with China at all levels. Ten years later, in the absence of American collaboration, China successfully launched its permanent space station in June 2021. It may be the appropriate time to revisit the Wolf Amendment to assess its long-term impact on China's progress in space station technology. This article traces and analyzes the ostensible reasons and underlying rationale why Congress passed the Wolf Amendment in 2011. It further discusses the response of the Chinese authority in space station technology after being excluded from the ISS. This will provide a platform to discuss the justification and effectiveness of the Wolf Amendment in protecting the integrity of American space technology, based on the concerns about the national pride, rather than national security, of the United States. This article concludes that excluding China from international cooperation in space exploration is a fruitless and unwarranted endeavor. [ABSTRACT FROM AUTHOR]

Objectives: Network real-time kinematic (RTK) technology can provide real-time and high-precision positioning service for users over the wide range, however, the current technology depends on high density of satellite navigation and positioning (SNAP) reference station network. To satisfy the high-precision positioning requirements based on the sparse reference station network, this paper recommends a net- work RTK service method based on virtual atmosphere constrait (VAC).Methods: Firstly, a non-combined double- difference observation model is constructed to solve and fix the network RTK baseline ambiguity quickly. Then, the baseline atmospheric delay is extracted and the slant path ionosphere and zenith trop- sphere are established respectively. Finally, the interpolated atmospheric delay and its accuracy information are regarded as virtual observations to improve the positioning performance of the terminal RTK. Based on a 205.1 km station spacing SNAP network from a northwest region， China, six rover stations inside and outside the network are used for termininal RTK verification. Results: The results show that the VAC net- work RTK service method can meet the needs of high-precision positioning users over large-scale reference networks. The terminal positioning accuracy and initialization speed by the VAC method are significantly improved by 61.64% and 9.96% compared with the traditional virtual reference station method. In this service mode, the average horizontal and vertical root mean squares of the fixed solution for the six terminals are 1.19 cm and 2.73 cm. Initializing RTK solution by a lot of times, 88.78% of periods can be fixed within 2 epochs for the six rover staions. Conclusions: The VAC service mode has good adaptability to both users inside and outside the large-scale SNAP base station network. [ABSTRACT FROM AUTHOR]

On 17 June 2021, China's spacecraft Shenzhou 12 took three Chinese astronauts into the Earth's orbit and docked with the assembly of Tianhe and Tianzhou, the core module and cargo ship of the Chinese Space Station (CSS), which had been launched and assembled in orbit earlier this year. The three astronauts became the first visitors of the CSS and would stay in orbit for about three months. In 2022, two laboratory cabin modules, Wentian and Mengtian, will be launched and assembled into Tianhe, completing the basic structure of the CSS. The CSS is designed to be used for at least 10 years, and will provide an outer space experimental platform for researchers from multiple disciplines. On 23 July 2021, National Science Review (NSR) interviewed Professor Ming Gao (高铭), the Commander-in-Chief of the Space Utilizaiton System of the China Manned Space Program, Director General of the Technology and Engineering Center for Space Utilization (CSU) of the Chinese Academy of Sciences and an Academician of the International Academy of Astronautics. The Space Utilizaiton System is the scientific part of the CSS project, responsible for the design and organization of the onboard research programs. Gao has been involved in China's Manned Space Program since 1994, and has experienced the whole development process from the Shenzhou spacecraft to the CSS. In this interview, she introduces the scientific goals, plans and aspirations of the CSS. [ABSTRACT FROM AUTHOR]

Copyright of South Architecture / Nanfang Jianzhu is the property of South Architecture Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The geostationary satellite-borne lightning measurements provide new and more effective way for lightning detection from space. In December 2016, Lightning Mapping Imager (LMI) onboard the Fengyun-4A (FY-4A) geostationary satellite was launched, which was the first satellite-borne lightning imager developed in China. Up to now, LMI has been working stably for more than 4 years to implement the continuous and effective lightning detections within China and its surrounding areas. In this study, the preliminary characteristics of measurements from LMI were analysed in detail by using the LMI data between 2018 and 2019. Moreover, the factors that affect the detection capability of LMI were investigated through an inter-comparison between the observations of LMI and International Space Station (ISS) Lightning Imaging Sensor (LIS). The results show that the LMI detection results are generally stable and reliable. The relative spatial distribution, monthly and diurnal variations, and the relative optical radiance of lightning observed by the LMI are consistent with those observed by ISS/LIS. However, the absolute values between the two sensors behave significant differences. Caused by the observation geometry, the detection results of LMI in low-latitude regions are more similar to those of ISS/LIS than in mid-latitude regions. In addition, there are some errors in the lightning radiance observed by LMI, which are possibly affected by the bright cloud background as well as radiometric calibration errors. Through targeted improvements to the onboard and ground algorithms for LMI, its detection capability can be greatly improved in future. [ABSTRACT FROM AUTHOR]

Efficient operation is important to make full use of the capabilities of China's space station. Determining the stochastic impacts of emergencies on the operational scenario of the space station is critical for successful implementation. However, few studies have assessed the uncertainties in the operational processes of the space station. To fill this gap, discrete event simulation (DES) is used to develop an evaluation method for the contingent operational plan of a space station. First, DES is used to develop a model framework of the space station operations, and the launch delay of cargo vehicles is introduced into the integrated simulation procedure. Second, the precision of the results and the computational efficiency are improved using the variance reduction technique. The corresponding effect on the number of simulation trials is confirmed using four constraints and three measurable metrics. Finally, the proposed method is applied to a two-year space station operational plan. The results show that maintaining a short interval between the launch date of the cargo vehicles and the start of the launch windows can decrease prolonged duration after a launch delay. A statistical analysis can be used to determine a safe interval between the dates of the events and vehicle launch. [ABSTRACT FROM AUTHOR]

The Cloud-Aerosol Transport System (CATS) lidar, on board the International Space Station (ISS), provides a new opportunity for studying aerosol vertical distributions, especially the diurnal variations, from space observations. In this study, we investigate the seasonal variations and diurnal cycles in the vertical aerosol extinction coefficients (AECs) over East Asia by taking advantage of 32 months of continuous and uniform aerosol measurements from the CATS lidar. Over the Tibetan Plateau, a belt of AECs at approximately 6 km between 30 and 38 ∘ N persistently exists in all seasons with an obvious seasonal variation. In summer, the aerosols at 6 km are identified as a mixture of both anthropogenic aerosols transported from India and coarse dust particles from Asian dust sources. In addition, the high AECs up to 8 km in summer over the Tibetan Plateau are caused by smoke aerosols from thermal dynamic processes. In fall and winter, the northern slope of the plateau is continuously influenced by both dust aerosols and polluted aerosols transported upslope from cities located at lower elevations in northwestern Asia. The diurnal variation in AECs in North China is mainly related to the diurnal variations in the transported dust and local polluted aerosols. Below 2 km , the AEC profiles in North China at 06:00 and 12:00 CST (China standard time) are significantly higher than those at 00:00 and 18:00 CST, reaching a maximum at midday. The aerosol vertical profiles over the Tarim Desert region in summer have obvious diurnal variations, and the AECs at 12:00 and 18:00 CST are significantly higher than those at 00:00 and 06:00 CST, which are induced by the strong diurnal variations in near-surface wind speeds. In addition, the peak in the AEC profiles has a significant seasonal variation, which is mainly determined by the boundary layer height. [ABSTRACT FROM AUTHOR]

The Lightning Mapping Imager (LMI) equipped on the FY-4A (FengYun-4A) geostationary satellite achieves lightning positioning through optical imaging and has the advantages of high temporal resolution, high stability, and continuous observation. In this study, FY-4A LMI lightning event, group and flash data from April to August 2018 are selected, and their quality are assessed through qualitative and quantitative comparison with the ground-based Advanced Time of Arrival and Direction system (ADTD) lightning observation network data and the American International Space Station (ISS) lightning imaging sensor (LIS) data. The results show that the spatial distributions of FY-4A lightning are consistent with those of the ground-based ADTD and ISS LIS. The temporal variation in FY-4A lightning group frequency is consistent with that of ADTD stroke, which reflects that FY-4A LMI can capture the lightning occurrence in inland China. Quantitative statistics show that the consistency rate of FY-4A LMI and ISS LIS events is relatively high but their consistency rate is lower in terms of lightning group and flash data. Compared with the lightning observations by the ISS LIS and the ground-based ADTD, FY-4A LMI reports fewer lightning events in the Tibetan Plateau. The application of Tibetan Plateau lightning data requires further processing and consideration. [ABSTRACT FROM AUTHOR]

The purpose of video process detection is to identify key processes of interest and associated semantic categories, which is an important computer vision task for localizing key processes in space science experiments. To detect experimental processes in space electrostatic suspension material experiment on China's Space Station, we propose a Slow-and-Fast Dual-Stream Network. It extracts multi-scale temporal semantic information by designing a Slow-and-Fast Temporal Stream structure and effectively detects the experimental processes with various temporal scales. In addition, the Two Path Temporal Pyramid Network (TP2N) enhances the bi-direction flow among multi-scale features on the temporal dimension to alleviate boundary sensitivity. The validation experiments on our established dataset demonstrate the effectiveness of our proposed method with 62.43% mAP, outperforming the related state-of-the-art temporal action localization methods with nearly 7% mAP gain. This paper is the first application of deep learning in space electrostatic suspension material experiments on China's Space Station and further provides important technical support for the identification of key processes in space science experiments. [ABSTRACT FROM AUTHOR]

This paper discusses the current state of non-destructive research on the density, surface tension and viscosity of molten samples using the electrostatic levitation furnace (ELF) aboard the China Space Station (CSS). To address the challenges posed by the microgravity environment during the non-destructive testing process of containerless technology, we have developed several solutions. These include a temperature correction for infrared temperature measurement, a dual-camera position correction technique for density testing, a double electrode synchronous excitation, semi-frequency excitation and fine-sweeping approach for surface tension testing, and a signal demodulation method for viscosity testing. The uncertainties of the three thermophysical properties were 0.51 %, 3.10 %, and 9.78 %, respectively. This study highlights the feasibility and accuracy of measurements conducted in the ELF on the CSS, offering valuable insights into the behavior of molten materials under microgravity conditions. The findings from this study significantly contribute to our understanding of the thermophysical properties of molten materials. [ABSTRACT FROM AUTHOR]

Sufficient evidence indicates that orbiting space stations contain diverse microbial populations, which may threaten astronaut health and equipment reliability. Understanding the composition of microbial communities in space stations will facilitate further development of targeted biological safety prevention and maintenance practices. Therefore, this study systematically investigated the microbial community of China's Space Station (CSS). Air and surface samples from 46 sites on the CSS and Assembly Integration and Test (AIT) center were collected, from which 40 bacteria strains were isolated and identified. Most isolates were cold- and desiccation-resistant and adapted to oligotrophic conditions. Bacillus was the dominant bacterial genus detected by both cultivation-based and Illumina MiSeq amplicon sequencing methods. Microbial contamination on the CSS was correlated with encapsulation staff activities. Analysis by spread plate and qPCR revealed that the CSS surface contained 2.24 × 103–5.47 × 103 CFU/100 cm2 culturable bacteria and 9.32 × 105–5.64 × 106 16S rRNA gene copies/100cm2; BacLight™ analysis revealed that the viable/total bacterial cell ratio was 1.98–13.28%. This is the first study to provide important systematic insights into the microbiome of the CSS during assembly that describes the pre-launch microbial diversity of the space station. Our findings revealed the following. (1) Bacillus strains and staff activities should be considered major concerns for future biological safety. (2) Autotrophic and multi-resistant microbial communities were widespread in the AIT environment. Although harsh cleaning methods reduced the number of microorganisms, stress-resistant strains were not completely removed. (3) Sampling, storage and analytical methods for the space station were thoroughly optimized, and are expected to be applicable to low-biomass environments in general. Microbiology-related future works will follow up to comprehensively understand the changing characteristics of microbial communities in CSS. [ABSTRACT FROM AUTHOR]

China Chang'E-3 performed soft landing at the plains of Sinus Iridum on lunar surface on December 14th 2013 successfully; it opened a new window for observing lunar surface with radiometric tracking which many lunar scientific researchers always pursue for. Since July 2014, OCEL (Observing Chang'E-3 Lander with VLBI) project has been conducted jointly by IVS (International VLBI Service of Geodesy and Astrometry) and BACC (Beijing Aerospace Control Center), a global IVS R&D network augmented with two China Deep Space Stations configured for OCEL. This paper presents the current status and preliminary result of the OCEL and mainly focuses on determination of the lander position, which is about 7 meter in height and 14 meter in plane of lunar surface with respect to LRO (Lunar Reconnaissance Orbiter). Based on accuracy analysis, further optimized OCEL sessions will make use of this target-of-opportunity, the Chang'E-3 lunar lander, as long as it is working. With higher accurate radiometric observables, more prospective contribution to earth and lunar science is expected by combining with LLR. [ABSTRACT FROM AUTHOR]

• Large-sized InSe single crystal. • The ground simulation apparatus of China space station. • γ-Phase with space group of standard R 3 m. • A positive thermal expansion at 30–500 °C. • No element volatilization even the temperature as high as 1000 °C. Indium selenide (InSe) semiconductor crystal was grown by using the ground simulation apparatus of China space station in this work. The furnace was controlled at 715 °C and the temperature gradient for crystal growth was ∼30 °C/cm. The as-grown InSe crystalizes in γ-phase with space group of R 3 m. The average etching pits density (EPD) is estimated to be about 104/cm2. Thermal analysis indicates a positive thermal expansion at 30–500 °C and no volatilization occurred even as high as 1000 °C. This work not only establishes a reliable process for preparing large-sized InSe single crystal but also creates a foundation for further work in outer space in the future. [ABSTRACT FROM AUTHOR]

With the development of the space station technology in China, the active vibration suppression of the lager flexible antennas and solar panels that mounted on the space station is demanded. The active vibration suppression is hard to achieve because these appendages are not allowed to mount actuators on it. Further, the practical goal is usually unachievable by the controller based on the unreliability or impracticality observed vibration parameters. In this paper, the active vibration suppression during the spacecraft attitude maneuver by the optical camera monitoring the dynamic behaviors of the flexible appendages is introduced under the restriction of the freedom of the actuators. The modal parameters of the flexible appendage used in the controller are obtained by the optical monitoring approach. A referenced angular velocity is set as the virtual input by the back-stepping control and Lyapunov method, and the control law is designed to track this virtual input. The constraint of the coefficient in the controller is investigated to guarantee the asymptotic convergence of the system considering angular velocity tracking error. The control manage coefficient is defined to describe the distribution coefficient of the vibration suppression in the design of control law. The relationship between the attitude maneuver accuracy and active vibration suppression is introduced. The appropriate control manage coefficient is obtained numerically. To guarantee the reliability or practicality of the designate flexible spacecraft control system, the optical measurements are used to measure the dynamic behaviors of the large flexible structures. The absence of displacement velocity sensors is compensated by the presence of appropriate dynamics in the controller. The results of simulation validate the feasibility of the proposed control strategy. [ABSTRACT FROM AUTHOR]