Petrography and mineral chemistry of 24 ordinary chondrites from the Grove Mountains, Antarctica, have been studied in order to identify their chemical-petrographic types. These samples were selected from a total of 4...Petrography and mineral chemistry of 24 ordinary chondrites from the Grove Mountains, Antarctica, have been studied in order to identify their chemical-petrographic types. These samples were selected from a total of 4448 Grove Mountains (GRV) meteorites collected during the 19th Chinese Antarctic Research Expedition so as to make an estimation of the large GRV meteorite collection. The chemical-petrographic types of these meteorites are presented below: 1 H3,2 H4, 4 H5, 2 H6, 1 L4, 7 L5, 5 L6, 1 LL4 and 1 LL6. The new data weaken the previous report that unequilibrated ordinary chondrites are unusually abundant in the Grove Mountains region. However, this work confirms significant differences in distribution patterns of chemical-petrographic types between the Grove Mountains and other regions in Antarctica. Many of these meteorites show significant terrestrial weathering, probably due to a high abundance ratio of meteorites found in moraines to those on blue ice. Nine meteorites experienced severe shock metamorphism, as evidenced by undulose extinction and intense fracturing of silicates and presence of shock-induced melt veins and pockets. These heavily shocked meteorites provided us with natural samples for the study of high-pressure polymorphs of minerals.展开更多
The data acquisition stations and the data processing center of the Science and Application Center for Lunar and Deep-space Exploration (SACLuDE) are located at different geographical sites. They respectively have the...The data acquisition stations and the data processing center of the Science and Application Center for Lunar and Deep-space Exploration (SACLuDE) are located at different geographical sites. They respectively have their own local networks and interconnect with each other through access to the core data network. This paper describes the clock drift in the computer and other networked devices building up the infrastructure of the above local networks. The network time variance of the stochastic model is also estimated. The poor precision of network synchronization will bring about potential hazards to the network operation and application running in the networks, which is clarified in the present paper. At the end of the paper, a cost-effective and feasible solution is proposed based on the Global Position System (GPS) and the Network Time Protocol (NTP).展开更多
It is essential to build a modern information management system to store and manage data of our circumlunar explorer in order to realize the scientific objectives. It is difficult for an information system based on tr...It is essential to build a modern information management system to store and manage data of our circumlunar explorer in order to realize the scientific objectives. It is difficult for an information system based on traditional distributed technology to communicate information and work together among heterogeneous systems in order to meet the new requirement of Internet development. XML and Web Services, because of their open standards and self-containing properties, have changed the mode of information organization and data management. Now they can provide a good solution for building an open, extendable, and compatible information management system, and facilitate interchanging and transferring of data among heterogeneous systems. On the basis of the three-tiered browse/server architectures and the Oracle 9i Database as an information storage platform, we have designed and implemented a data archiving and retrieval system for the circumlunar explorer-LUNARINFO. We have also successfully realized the integration between LUNARINFO and the cosmic dust database system. LUNARINFO consists of five function modules for data management, information publishing, system management, data retrieval, and interface integration. Based on XML and Web Services, it not only is an information database system for archiving, long-term storing, retrieving and publication of lunar reference data related to the circumlunar explorer, but also provides data web Services which can be easily developed by various expert groups and connected to the common information system to realize data resource integration.展开更多
Space debris, here referring to all non-operating orbital objects, has steadily increased in number so that it has become a potential barrier to the exploration of space. The ever-increasing number of space debris pie...Space debris, here referring to all non-operating orbital objects, has steadily increased in number so that it has become a potential barrier to the exploration of space. The ever-increasing number of space debris pieces in space has created an increasingly threatening hazard to all on-the-orbit spacecraft, and all future space exploration activities have to be designed and operated with respect to the increasing threat posed by space debris. Generally, space debris is classified as large, medium and small debris pieces based on their sizes. The large debris piece is easily catalogued, but medium to small debris pieces are very difficult to track and also quite different in damage mechanisms from the large ones. In this paper, a scheme of chemical classification of space debris is developed. In our scheme, the first-order classification is employed to divide space debris into two groups: natural micrometeoroids and artificial space debris. The second-order classification is based on their chemical patterns and compositions. The natural micrometeoroids are further divided into three types, namely mafic, metal and phyllosilicate micrometeorites, while the artificial space debris is divided into seven types, which are polymers, non-metal debris, metals and their alloys, oxides, sulphides and their analogs, halides and carbides. Of the latter seven types, some can also be further divided into several sub-types. Chemical classification of space debris is very useful for the study of the chemical damage mechanism of small debris pieces, and also is of great significance in constraining the origin and source of space debris and assessing their impact on spacecraft and human space activities.展开更多
文摘Petrography and mineral chemistry of 24 ordinary chondrites from the Grove Mountains, Antarctica, have been studied in order to identify their chemical-petrographic types. These samples were selected from a total of 4448 Grove Mountains (GRV) meteorites collected during the 19th Chinese Antarctic Research Expedition so as to make an estimation of the large GRV meteorite collection. The chemical-petrographic types of these meteorites are presented below: 1 H3,2 H4, 4 H5, 2 H6, 1 L4, 7 L5, 5 L6, 1 LL4 and 1 LL6. The new data weaken the previous report that unequilibrated ordinary chondrites are unusually abundant in the Grove Mountains region. However, this work confirms significant differences in distribution patterns of chemical-petrographic types between the Grove Mountains and other regions in Antarctica. Many of these meteorites show significant terrestrial weathering, probably due to a high abundance ratio of meteorites found in moraines to those on blue ice. Nine meteorites experienced severe shock metamorphism, as evidenced by undulose extinction and intense fracturing of silicates and presence of shock-induced melt veins and pockets. These heavily shocked meteorites provided us with natural samples for the study of high-pressure polymorphs of minerals.
文摘The data acquisition stations and the data processing center of the Science and Application Center for Lunar and Deep-space Exploration (SACLuDE) are located at different geographical sites. They respectively have their own local networks and interconnect with each other through access to the core data network. This paper describes the clock drift in the computer and other networked devices building up the infrastructure of the above local networks. The network time variance of the stochastic model is also estimated. The poor precision of network synchronization will bring about potential hazards to the network operation and application running in the networks, which is clarified in the present paper. At the end of the paper, a cost-effective and feasible solution is proposed based on the Global Position System (GPS) and the Network Time Protocol (NTP).
文摘It is essential to build a modern information management system to store and manage data of our circumlunar explorer in order to realize the scientific objectives. It is difficult for an information system based on traditional distributed technology to communicate information and work together among heterogeneous systems in order to meet the new requirement of Internet development. XML and Web Services, because of their open standards and self-containing properties, have changed the mode of information organization and data management. Now they can provide a good solution for building an open, extendable, and compatible information management system, and facilitate interchanging and transferring of data among heterogeneous systems. On the basis of the three-tiered browse/server architectures and the Oracle 9i Database as an information storage platform, we have designed and implemented a data archiving and retrieval system for the circumlunar explorer-LUNARINFO. We have also successfully realized the integration between LUNARINFO and the cosmic dust database system. LUNARINFO consists of five function modules for data management, information publishing, system management, data retrieval, and interface integration. Based on XML and Web Services, it not only is an information database system for archiving, long-term storing, retrieving and publication of lunar reference data related to the circumlunar explorer, but also provides data web Services which can be easily developed by various expert groups and connected to the common information system to realize data resource integration.
基金This work was supported jointly by the China National Space Administration(Grant No.KJSP2002-0201/02)in part by the National Natural Science Foundation of China(Grant Nos.49973025 and 49773204)the Chinese Academy of Sciences(Grant Nos.KZCX2-115 and KGCX2-406).
文摘Space debris, here referring to all non-operating orbital objects, has steadily increased in number so that it has become a potential barrier to the exploration of space. The ever-increasing number of space debris pieces in space has created an increasingly threatening hazard to all on-the-orbit spacecraft, and all future space exploration activities have to be designed and operated with respect to the increasing threat posed by space debris. Generally, space debris is classified as large, medium and small debris pieces based on their sizes. The large debris piece is easily catalogued, but medium to small debris pieces are very difficult to track and also quite different in damage mechanisms from the large ones. In this paper, a scheme of chemical classification of space debris is developed. In our scheme, the first-order classification is employed to divide space debris into two groups: natural micrometeoroids and artificial space debris. The second-order classification is based on their chemical patterns and compositions. The natural micrometeoroids are further divided into three types, namely mafic, metal and phyllosilicate micrometeorites, while the artificial space debris is divided into seven types, which are polymers, non-metal debris, metals and their alloys, oxides, sulphides and their analogs, halides and carbides. Of the latter seven types, some can also be further divided into several sub-types. Chemical classification of space debris is very useful for the study of the chemical damage mechanism of small debris pieces, and also is of great significance in constraining the origin and source of space debris and assessing their impact on spacecraft and human space activities.
