Current Issue

2024, Volume 44,  Issue 1

Review of NASA’s Progress and Achievements in 2023
FAN Weiwei, HAN Lin, WANG Haiming, YANG Fan
2024, 44(1): 1-4. doi: 10.11728/cjss2024.01.2024-yg04
Abstract:
In 2023, NASA pushed the boundaries of exploration, explored the unknown in air and space, continued to make new scientific discoveries in the fields of Moon to Mars, climate and Earth sciences, manned spaceflight, solar system and beyond, space technology innovation, and aerospace technology, and inspired the world through discovery. And these scientific discoveries are widely publicized to draw people’s attention to space exploration. For example, NASA shared results of its first Moon to Mars Architecture Concept Review as it builds a blueprint for human exploration throughout the solar system for the benefit of humanity. The “Artemis” plan for manned lunar exploration series of missions and the development of various systems continue to progress. NASA’s Webb telescope pulled back the curtain on some of the most distant galaxies, stars, and black holes ever observed. A number of asteroid exploration missions have made significant progress. Space-based and airborne platforms have cooperated to better understand the changing planet. NASA’s Deep Space Optical Communications experiment beamed back a laser encoded with test data from nearly 10 million miles away. NASA also worked with Boeing on the Sustainable Flight Demonstrator project to build and test the X-66A. NASA is also actively inspiring and guiding the next generation of interest and participation in space exploration.
Progress on Exoplanet Detection and Research in Space
ZHOU Jilin, XIE Jiwei, GE Jian, JI Jianghui, DOU Jiangpei, DONG Subo, LIU Huigen, WANG Wei, GUO Jianheng, YU Cong, BAI Xuening, FENG Fabo, LIU Beibei
2024, 44(1): 5-18. doi: 10.11728/cjss2024.01.2024-yg01
Abstract:
The subject of exoplanets has been a rapidly developing discipline in the past thirty years. Its main research content and objectives include: detecting exoplanets through the development of various detection techniques, analyzing planetary orbits, composition and atmospheric properties, evaluating the habitability of planets, calculating the distribution patterns of planets, and revealing the formation and dynamical evolution of planetary systems from both theoretical and observational perspectives. The study of exoplanets is of great significance in answering questions about the existence of other life forms in the universe and the status of humans in the universe. With the development of space exploration technology in the 21st century, the study of exoplanets has entered a new era. This article summarizes the development trend in the field of exoplanets, condenses China’s key areas for future space exploration of exoplanets, optimizes the discipline layout, and promotes high-quality development of exoplanet research.
History and Implications of Asteroid Exploration
WEI Sijia, HE Yuyang, LIU Tianyu, YANG Wei, LIN Yangting
2024, 44(1): 19-50. doi: 10.11728/cjss2024.01.2024-yg02
Abstract:
Since 1989, the Galileo spacecraft has passed asteroids 951 Gaspra and 243 Ida on its journey to Jupiter, with asteroid exploration gradually becoming a crucial aspect of deep space exploration for major aerospace nations. Over the past three decades, the asteroid exploration has evolved from mere flybys to targeted explorations, and eventually to sample return missions. During the process, the types of targets have become more diverse, and the objectives have shifted from purely scientific exploration to asteroid defense and resource utilization. In 2025, China plans the Tianwen-2 asteroid exploration mission and its first asteroid defense mission. To better serve China’s future missions, this paper reviews the asteroid exploration history, their scientific goals, payloads, and scientific contributions. For sample return missions, a detailed review of sample storage and distribution management was provided, as well as the preliminary ground laboratory analysis of Hayabusa and Hayabusa 2, and OSIRIS-REx missions. Planning low-cost, high-freguency sample-return missions, reinforcing mission collaborations,and establishing scientific design teams can better serve China’s future asteroid explorations.
Estimation of Energy Input during Throat Aurora Processes
FAN Tianshu, CAO Yongjun, QIU Huixuan, WANG Zhiwei, HAN Desheng
2024, 44(1): 51-59. doi: 10.11728/cjss2024.01.2023-0065
Abstract:
The throat aurora is a kind of discrete auroras occurred around the Magnetic Local Noon (MLN). The discrete arc is almost vertical to the auroral oval and extends equatorward. Previous studies have shown that the throat auroral structure corresponds to the localized magnetopause indentations which are related to the particular magnetopause reconnection. As is known, magnetic reconnection is the important approach inputting energy of solar wind, so the research of energy input of throat aurora is key to understand this particular magnetopause reconnection. A new way to estimate the energy input by using all auroral events happened on December 2015 is built. A relational expression about auroral intensity and energy flux of electronic precipitation is set up by observations of both ground station and satellite. Estimating the total energy input of a typical throat auroral event which lasted three minutes and happened on 8 December 2015 by this relational expression, and the answer is about $ 1.07\times {10}^{11}\;\mathrm{J} $. And the average power of input energy per area is about $ 1.31\times {10}^{-4}\;\mathrm{W} \cdot {\mathrm{m}}^{-2} $. Compared with the usual polar gap energy input results given by MHD simulation in previous studies, the energy input efficiency of the throat auroral process given in this paper is about twice that of the MHD simulation results, which indicates that the energy input accompanying the throat auroral process is very considerable and may cause local space weather effects.
Seasonal Variations of Global Ionospheric NmF2 and hmF2
LI Bo, CUI Ruifei, WENG Libin
2024, 44(1): 60-70. doi: 10.11728/cjss2024.01.2023-0130
Abstract:
The seasonal variations of global ionospheric NmF2 and hmF2 have been analyzed by using the monthly COSMIC ionospheric data from 2006 to 2019 and wavelet analysis method. The results show that the ionospheric NmF2 and hmF2 are significantly different with local time, season and latitude. The ionospheric peak parameters have positive correlation with the solar activity, and their correlation coefficients are above 0.9 and 0.8, respectively. The ionospheric NmF2 at noon exists significantly annual and semiannual variations, especially under the high solar activity conditions. However, the annual variation of ionospheric NmF2 has been mainly observed at nighttime. Meanwhile, the annual variation of ionospheric hmF2 at noon is significant in all years, but almost absent during midnight. Additionally, and the seasonal variations of ionospheric NmF2 and hmF2 in the southern hemisphere are more obvious than that in the northern hemisphere. Additionally, the seasonal variations of ionospheric peak parameters are more significant during high solar activity years. Moreover, there seem to be periodic signals of 25~35 months in the solar activity index and ionospheric peak parameters, but their power spectrum are not greater than 95% significance level, and we thought that the ionosphere would be not affected by the QBO signal.
COSMIC Ionospheric Occultation Inversion Simulation and Constellation Optimization Research
XU Bobo, WANG Cheng, ZHANG Yulu, WEN Yuanlan, HE Lina, LI Zhen
2024, 44(1): 71-79. doi: 10.11728/cjss2024.01.2022-0072
Abstract:
Using precise GNSS ephemeris and the NeQuick model, we simulated the geometric process and physical data of COSMIC ionospheric Radio Occultation (RO), and inverted the three-dimensional electron density of the ionosphere using the calibrated TEC method and “onion layering” algorithm. The obtained electron density profile was found to be consistent with the model trend with small deviations. The absolute errors of ionospheric hmF2 and NmF2 were 4.2 km and 0.26×104 cm–3, respectively, with relative errors of 1.66% and 4.95%, respectively. The linear regression coefficient of determination R2 for the ionospheric hmF2 and NmF2 inversion results and model values were 0.956 and 0.950, respectively, indicating the completeness, correctness, and effectiveness of the occultation inversion simulation. Building on the correct geometric simulation, we analyzed the occultation observation performance of COSMIC-2 and the influence of multi-GNSS on the number and spatial distribution characteristics of occultation. It is found that the number of navigation satellites participating in the occultation observation is proportional to the occultation event, and the uniformity of the occultation distribution significantly improves with the increase in navigation satellites. To enhance the timeliness of future occultation events and the uniformity of their spatial and temporal distribution, the uniformity index of occultation distribution is proposed and improved the COSMIC-2B using a fast non-dominated sorting genetic algorithm to determine the optimal total number of occultation satellites, number of orbital planes, and orbital inclination. The optimal configuration of 38/19/1∶800 km, 75.21° was found, achieving the design goals of N≤40, F=1, h=800 km, 72°≤i<90°. With 106 satellites including GPS, Galileo, GLONASS, and BDS-3 in one hour, this configuration can observe 2675 occultation events with uniform spatial and temporal distribution.
Automatic Generation of Artificial Space Weather Forecast Product Based on Sequence-to-sequence Model
LUO Guanting, ZOU Yenan, CAI Yanxia
2024, 44(1): 80-94. doi: 10.11728/cjss2024.01.2023-0029
Abstract:
Both analyzing a large amount of space weather observed data and alleviating personal experience bias are significant challenges in generating artificial space weather forecast products. With the use of natural language generation methods based on the sequence-to-sequence model, space weather forecast texts can be automatically generated. To conduct our generation tasks at a fine-grained level, a taxonomy of space weather phenomena based on descriptions is presented. Then, our MDH (Multi-Domain Hybrid) model is proposed for generating space weather summaries in two stages. This model is composed of three sequence-to-sequence-based deep neural network sub-models (one Bidirectional Auto-Regressive Transformers pre-trained model and two Transformer models). Then, to evaluate how well MDH performs, quality evaluation metrics based on two prevalent automatic metrics and our innovative human metric are presented. The comprehensive scores of the three summaries generating tasks on testing datasets are 70.87, 93.50, and 92.69, respectively. The results suggest that MDH can generate space weather summaries with high accuracy and coherence, as well as suitable length, which can assist forecasters in generating high-quality space weather forecast products, despite the data being starved.
Acceleration of Remote Sensing Image Filtering Based on Embedded CPU+GPU Heterogeneous Platform
TAN Pengyuan, XUE Changbin, ZHOU Li
2024, 44(1): 95-102. doi: 10.11728/cjss2024.01.2023-0033
Abstract:
A method is proposed for accelerating remote sensing image filtering in real-time using an embedded CPU + GPU heterogeneous platform for satellite-based image processing. the algorithm was initially parallelized through data division and mapping, leveraging the parallel computing capabilities of the GPU. Subsequently, hardware resources like the vector unit and cache of the GPU were employed to enhance algorithm speed through vectorization, vector permutation, and workgroup tuning. The feasibility and efficiency of this accelerated design were validated on an embedded development board. The experiments demonstrate a speedup ranging from 4.08 to 16.92 times when incorporating GPU parallel processing, compared to the serial implementation on a single CPU. Further optimization using GPU hardware resources can push the speedup to 15.38 to 56.41 times.
Land Cover Classification from Hyperspectral Data in the Water Ecological Space of Miyun Reservoir
CHEN Zhulin, LI Tianyu, ZHANG Yaofang, XUE Wanlai, XIE Ying, WU Di, ZHAO Chenqiang, MA Li, WANG Siqi, JIA Kun
2024, 44(1): 103-113. doi: 10.11728/cjss2024.01.2023-0035
Abstract:
With the acceleration of China’s urbanization process, the problem of the structure and function of water ecological space has become increasingly severe. Monitoring the detailed distribution of land cover types in the key water ecological space is critical for their health assessment and future ecological planning. This study investigated a hybrid feature selection algorithm and GF-5 hyperspectral data (with a spatial resolution of 30 m) to generate a fine land cover classification method for the water ecological space of Miyun Reservoir in Beijing. Firstly, the feature importance ranking was determined using the Random Forest (RF) algorithm and several feature subsets were generated with feature amount gradually carried out in a step size of 10. Then, the classification model was generated based on each subset using the RF algorithm. The feature subset that achieved the highest overall classification accuracy was determined as the initial feature subset. Next, the backward sequential selection algorithm was used to this initial subset to search for the best feature subset. Finally, the classification model of the water ecological space of Miyun Reservoir was generated based on the best feature subset and RF algorithm. To validate the advance of GF-5 hyperspectral data, this study also developed a classification model using Sentinel-2 multispectral data (with a spatial resolution of 10 m) for comparison. The results indicated that hyperspectral data achieved high classification accuracy (overall classification accuracy of 93.61%, and Kappa coefficient of 91.71%), especially in the accurate recognition of tree species (The producer's accuracy and user's accuracy of the chestnut forest are 81.25% and 73.03%, respectively). The reflectance of shortwave infrared bands of GF-5 data has increased the differentiation between chestnut forests and other tree species. By contrast, Sentinel-2 data-based model achieved lower classification accuracy with an overall accuracy of 85.91% and a Kappa coefficient of 82.00%. This result indicated that although Sentinel-2 data has higher spatial resolution than GF-5 data, it still has difficulty identifying chestnut forests due to a lack of fine band information. The classification algorithm proposed in this study can provide accurate basic data for supporting the rational planning and management of water ecological spaces.
Microgravity and Space Life Science
Investigation on Performance Difference of 35 K Cryogenic Heat Transfer System in Ground and Space Environment
GUO Yuandong, LIU Sixue, ZHANG Hongxing, MIAO Jianyin, ZHAO Jianfu, LIN Guiping
2024, 44(1): 114-121. doi: 10.11728/cjss2024.01.2023-yg13
Abstract:
In order to solve the problem of cryogenic heat dissipation of space infrared detection system and ensure its cryogenic operating environment, an integrated system of cryogenic acquisition and heat transfer in 35 K temperature range was designed and developed based on pulse tube cooler and cryogenic loop heat pipe. The system consists of a neon cryogenic loop heat pipe, two sets of pulse tube cooler in 35 K temperature range, one pulse tube cooler in 150 K temperature range, thermal insulation screen, temperature measurement / heating components, control system. It has completed ground single-level and satellite-level thermal vacuum tests, and completed space flight tests in 2020. Heat transfer tests under horizontal attitude and anti-gravity conditions were carried out in the ground stand-alone test to ensure that the system could work stably in space microgravity. The whole-satellite test verified the working characteristics of the system under the heat dissipation condition of the satellite platform, and the space flight test obtained the working performance of the system under space microgravity. This paper introduces the thermal performance of the system in different stages, including supercritical start-up characteristics, steady-state operation performance, etc. The results have verified the correctness of relevant design, and this paper focuses on comparing the performance differences in different stages, and analyzes the possible reasons.
On Bubble Departure Radius in Liquid Oxygen Tank of Rocket Propulsion System under Microgravity
LI Wentao, HUANG Wenhao, LIANG Guozhu
2024, 44(1): 122-132. doi: 10.11728/cjss2024.01.2023-0003
Abstract:
Studying the bubble departure radius in the liquid oxygen tank under microgravity is the basis for the propellant boiling and heat transfer calculation of the launch vehicle propulsion system in orbit. Unlike regular or low gravity environments, the Marangoni effect becomes essential in microgravity. To calculate the bubble departure radius, Firstly, a bubble dynamics model is developed, including buoyancy, inertia, pressure, surface tension, drag, and Marangoni forces. Secondly, to solve the problem of the narrow application range of the existing Marangoni force formulas, a more accurate correction factor is fitted by numerical simulation. Consequently, the Marangoni force model is extended. Finally, using the physical parameters of saturated liquid oxygen at 0.3 MPa, a conventional working pressure for the liquid oxygen tank of the launch vehicle, the change of the total force with the radius and the departure radius with gravity are calculated, respectively. The results show that bubbles' departure behavior can be divided into three zones: microgravity zone, transition zone, and low gravity zone. The microgravity zone can form large bubbles of a centimeter or even meter scale, while the low gravity zone can only form tiny bubbles of 0.1 mm scale. Compared with the previous models, the model in this work can be applied to all three zones. Therefore, it comprehensively reveals the bubble departure characteristics in the liquid oxygen tank under microgravity. It can also provide theoretical support for analyzing the heat transfer characteristics in the liquid oxygen tank.
Antagonistic Effects of Resveratrol on Reproductive Injury in Hind-limp Unloading Male Rats
XUAN Yingying, YANG Yutian, SUN Yuehong, CAI Nan, TANG Hanqin, LI Liang, CHEN Keming
2024, 44(1): 133-141. doi: 10.11728/cjss2024.01.2023-0063
Abstract:
To research the antagonistic effect of resveratrol on reproductive injury in hind-limp unloading male rats. The 30 experimental rats were randomly divided into placebo control group, hind-limp unloading group, and HU+Res group. The HU+Res group was given resveratrol at the dose of 30 mg·kg–1 respectively every two days, and the placebo control group and hind-limp unloading groups were given equal volume of physiological saline. After 28 days, all rats were executed, and testes and epididymis were taken for histopathology detection, tissue biochemical index detection, and protein expression analysis of testicular tissue. Compared with the placebo control group, the weight of testes and epididymis in the hind-limp unloading group was significantly reduced, and resveratrol could significantly improve these indicators. The results of histopathology showed that the number of seminiferous epithelium layers and the area of intercellular substance in the hind-limp unloading group were significantly reduced, with obvious edema, and the number of spermatogonium was significantly reduced. After treatment with resveratrol, the morphology of testicular tissue was partially restored. The detection results of oxidative stress and inflammatory factor levels showed that compared with the placebo control group, the hind-limp unloading group showed an imbalance in oxidative stress levels in the testicular tissue of rats, with a significant increase in inflammatory factor levels. After treatment with resveratrol, this harmful situation could be significantly reversed. Western blot results showed that resveratrol significantly reduced the expression levels of Bax in the testicular tissue of hind-limp unloading male rats, and increased the expression levels of Bcl-2, p-PI3K/PI3K, p-AKT/AKT. Conclusions resveratrol of 30 mg·kg–1 may exert a antagonistic effect on reproductive damage in hind-limp unloading male rats by activating the PI3K/AKT signaling pathway.
Space Exploration Technology
BDS/GPS Zenith Tropospheric Delay Estimation and Its Effect on Precise Point Positioning
DENG Biao, WANG Weina, WANG Yanxia
2024, 44(1): 142-150. doi: 10.11728/cjss2024.01.2022-0051
Abstract:
The influence of zenith wet delay parameter estimation and horizontal troposphere gradient processing strategy on precise point positioning is studied, Six zenith tropospheric delay processing schemes were designed and experimented on the basis of the measured data from nine Multi-GNSS Experiment stations. The experimental results show that, during the 8 h observation period, it is not suitable to use the random walk model to deal with the horizontal troposphere gradient of the zenith wet delay in the BDS/GPS Precise Point Positioning mode; and the strategies of estimating the zenith wet delay parameter by random walk and handling the horizontal troposphere gradient without estimating or using the piecewise constant are relatively advantageous. The results of the dynamic and static precise point positioning show that the BDS/GPS strategy of estimating the zenith wet delay parameter and processing the horizontal troposphere gradient with piecewise constant or random walk is relatively superior, while the strategy of processing the horizontal troposphere gradient with random walk is slightly weaker. Overall, the zenith tropospheric delay and precise point positioning accuracy estimated by BDS is slightly weaker than that by GPS; the differences in the results of the six schemes around the ocean are larger than those of the inland stations. In the static Precise Point Positioning mode, with the increase of observation time, the trend of Precise Point Positioning errors of the six schemes tends to be the same, and the error size is basically within 2 cm. When the observation time is longer than 12 h, the strategy of estimating the zenith wet delay parameter by random walk and not considering the horizontal troposphere gradient is better overall.
Method of Spacecraft Maneuver Detection Based on Two-line Elements
CUI Wen, GUO Chao, ZHANG Wei
2024, 44(1): 151-158. doi: 10.11728/cjss2024.01.2023-0001
Abstract:
Due to the missions and orbit types of different spacecraft are quite different, orbit maneuvers must be conducted by spacecraft irregularly to ensure that they could complete their tasks successfully. For the non-cooperative spacecraft, their possible orbit maneuvers are usually unknown and very difficult to predict in advance, so it is necessary to identify possible orbit maneuver events in order to adjust spacecraft detection strategy in time. Two-Line Element (TLE for short) published by the USA, has the advantages of stable source, fast update frequency and easy acquisition, so it is proper to carry out the research on the method of spacecraft maneuver detection based on TLE. According to laws of operation and orbit control of spacecraft, this paper proposed a method based on TLE to detect maneuver events, which happened in the orbit plane of spacecraft, by checking and comparing the changes in semi-major axis and minimum ranges between two TLEs. The TLEs, from June, 2019 to September, 2019, of two spacecraft, METOP-A1 and IRNSS 1G, were taken for example to demonstrate the operating procedures and steps of maneuver detection using this method. Then, a large number of TLEs were generated by simulation, and on the basis, some calculations of maneuver detection were conducted correspondingly. From the statistical result, it could be found that the deviation of maneuver detection results was influenced by the own precision of TLEs and the amplitude of changes in semi-major axis. This method could effectively solve the problem of detecting the time and changes in semi-major axis of in-plane maneuvers, and identifying multiple maneuvers, so its effectiveness and usability was fully proved.
On-orbit Distributed Negotiation Intelligent Mission Planning for Instant Response
LI Yingyu, SHI Haoying, ZHAO Tong
2024, 44(1): 159-168. doi: 10.11728/cjss2024.01.2022-0074
Abstract:
The mission planning of LEO remote sensing constellation is a complex multi-objective optimization problem. At present, there are some problems in satellite mission planning research based on deep reinforcement learning, such as small scale of test data constellation, single optimization objective, repeated task arrangement and poor model adaptability. To solve the above problems, the CON_DQN (Contract network and Deep Q Network, CON_DQN) algorithm is proposed in this paper, which adopts the master-slave on-orbit distributed negotiation mechanism, the slave satellite makes decisions based on the planning, and the master satellite makes multi-objective optimization decisions from the aspects of priority, resource cost and load balancing based on the deep reinforcement learning algorithm, and processes on-orbit distributed negotiation intelligent mission planning for instant response. Aiming at the scene where the user demand reaches the key observation area dynamically at high frequency, the simulation experiment of different scale task sets of 100-star constellation is carried out. The results show that the proposed algorithm has a fast response speed and can achieve higher task benefits.
Design and Verification of Wide-band Search Coil Magnetometer Based on Transimpedance Preamplifier
ZHOU Bin, XUE Yongliang, TAO Ran, CHENG Bingjun, WANG Zidong, ZHANG Haibo, WU Xinzhe
2024, 44(1): 169-177. doi: 10.11728/cjss2024.01.2022-0073
Abstract:
The search coil magnetometer is widely used in space exploration and geological prospecting due to its high sensitivity and low noise level. This study presents a search coil sensor based on a transimpedance preamplifier to achieve a wide frequency bandwidth. The sensor directly connects the output signal of the inductive coil to the transimpedance preamplifier, which converts the AC magnetic field signal into an electrical signal. A signal transfer model of a magnetic sensor based on a transimpedance preamplifier is established, and the theoretical formula for sensitivity and noise is deduced. The search coil sensor is designed and developed using this formula to achieve a bandwidth of 0.01~10 kHz and a noise level of 1 fT·Hz–1/2 at 1~10 kHz. A signal modulation method evaluates the sensor’s performance for efficient amplitude and phase extraction at a specific frequency. The dual sensor differential method eliminates environmental interference during sensor noise assessment, and a phase difference analysis evaluates the homologous frequency bands of signals detected by two probes. As a result, the sensor achieves a 1 fT·Hz–1/2 noise level in the 1 kHz to 10 kHz range.
Design and Verification of Multi-detection Unit Based on ASIC Chip
ZHANG Xin, XU Wanqiu, BAI Chaoping, SUN Yueqiang, WANG Wenjing, ZHANG Shuai, HAN Jianwei, CHEN Rui, ZHU Xiang, LI Yue
2024, 44(1): 178-184. doi: 10.11728/cjss2024.01.2023-0018
Abstract:
Taking particles in space radiation environment as the research background, the space particle detection system using silicon micro-strip sensor as the probe and integrated chip IDE3160 for signal processing is developed. The system is designed by using silicon micro-strip detection array, which is composed of two silicon micro-strip sensors as the front-end probe, and using digital signal processing method to obtain the position of space particle incident and the energy deposited in the unit length (Linear Energy Transfer, LET) in the silicon micro-strip. From the perspective of the physical mechanism inducing single particle effects, the physical effects produced by contrasting heavy ions and pulsed lasers in silicon semiconductors are different. Pulsed laser of 1.064 μm was used to test the system, and good LET linearity results were obtained: The time required for data acquisition is 2.47 ms, the detectable LET threshold is about 0.1 MeV·cm2·mg–1 and the Pearson correlation coefficient is about 0.998, indicating that the system measurement is in good agreement with the theoretical design. The system has a wide dynamic range, good linearity, high integration, scalability and portability, and can be mounted on a variety of space exploration satellites.
Application Research and Design of XFDU on Definition of Telemetry Data
TAN Jie, LYU Liangqing, WANG Yuze
2024, 44(1): 185-191. doi: 10.11728/cjss2024.01.2023-0021
Abstract:
Design of fixed data format on spacecraft can cause problems such as data redundancy, unnecessary data occupying downlink bandwidth, and transferring undesired or useless data. In order to solve these problems, a data format encapsulation method which adopting CCSDS XFDU standard referencing to XFDU design method in OAIS model, and a data definition model based on parameter definition method in PUS are proposed. Corresponding designs including metadata XML schema of data definition model, metadata code table and XFDU format file are given. Then a XFDU converter was designed and tested, to support transforming binary data strings which descript data format into XML file, to generate metadata text according to metadata XML schema. A universal XFDU converter can be used in different systems to recognize and explain data format, to support heterogeneous information understanding among heterogeneous systems. Using XFDU can make the telemetry data definition model connecting to OAIS model, and will be in favor of data transferring, processing and preservation. This flexible data definition method will be a way of satellite definition.