Research on the method for the construction of Space Situational Intelligent Cognitive ability based on knowledge engineering

With the rapid rising demands of the Space Situation Awareness (SSA), this paper mainly focuses on the construction task of the cognitive ability for understanding space situation and administrating the space domain facilities much quicker and better. After clarifying the definition of Space Situation Cognition (SSC), the multi-scale system model has been conducted for knowledge acquisition, knowledge understanding and knowledge reasoning of SSC based on the knowledge engineering. Finally, the technical route and solution for the overall construction of intelligent cognition of space situation are put forward. It is an important way to form effective cognition of spatial situation by reasonably integrating and analysing spatial situation information that can be obtained through effective system integration.


Introduction
With the rapid development of space science and technology in recent years, human activities in space have been significantly upgraded. Space activities have penetrated into all fields of national economy and people's livelihood, and the security of space assets has been highly concerned by various governments. As more and more activities and purposes can be accomplished in the space field, and exploration continues to be launched into the deep space, there is also a proliferation of man-made objects in space, including spacecraft, rocket stages, arrow fragments, space debris and so on. For more and more complex space environment, effective space environment management is needed, the first is to complete space situation awareness.
Leveraging the growing volumes of orbital debris and SSA data will create a more complete picture of the orbital space environment [1]. There were some research about SSA in European Space Agency, which figured out the solution as correct data interpretation, sharing orbital debris and SSA data, terminology harmonization, and knowledge or domain modelling. Ontology engineering were proposed for the orbital debris domain [2]. The research from R.J. Revetto Group also complete a dynamic ontological system that accurate represents the orbital space domain by precisely formalizing the categories, interrelationships, and principles.
For further research, space elements model is still the subject for exploration based on the ontology model theory in this paper. Besides, the mastery and cognition of space situation is an important process for human beings to continuously expand their space vision and make continuous progress in space technology. This paper mainly focuses on the task of building cognitive ability of space situation, and realizes effective knowledge acquisition, knowledge understanding and knowledge reasoning of space situation through knowledge engineering technology.

Space Situational Awareness(SSA)
As the concept of situational awareness has been widely accepted by people, the basic understanding of situational awareness is mainly based on Endsley three-layer model, that is, the awareness and understanding of environmental elements and the prediction of future state under certain time and space conditions. In 2007, the "Airspace Surveillance and Intelligence Integration Program --ADSII Program" [3] proposed by the Federation of American Scientists carried out in-depth analysis on the realization of the awareness concept in the aviation field. In December 2013, the "National Maritime Strategic Security Program" [4] proposed by the Office of the President of the United States completed further deployment of situational awareness activities.
The concept of perception in the space field mainly refers to space situation awareness (SSA). Space situation awareness [5][6] is an activity that obtains space target information through detection, analyses space target situation and its impact on human beings, and its main task is to accurately detect and track space targets. Identify important characteristics such as size, shape and orbit parameters of space targets that may pose a threat to space systems, and classify and distribute target characteristic data. Space situational awareness, as the basic ability to maintain space assets and space activities, has also attracted much attention and reliance.

Space Domain Awareness(SDA)
Space Domain Awareness (SDA) is a situational Awareness activity that expands Space situational Awareness (SSA) based on existing facilities, equipment, policies and regulations, and takes into account operators, commanders, and ground-based facilities and other factors related to the Space environment. That is, celestial awareness is the knowledge that is used to predict, avoid, prevent, pass, recover, or otherwise invalidate or degrade spatial capabilities or services. [7] Its main purpose is to provide quantifiable and timely evidence for the decision-making process of specific space threats or hazards, including information processing, collection, fusion, utilization, quantification, extraction and other related work, and ultimately to effectively identify and predict threats and hazards.

Space Situation Cognition(SSC)
In terms of spatial situation cognition, the current research is still in the preliminary stage, and most of the existing research focuses on the process of situation information acquisition and visualization display. In this paper, we defined the concept of Space Situation Cognition as below: Definition-1 SSC: it is an orderly synthesis of situation description, situation understanding and situation prediction to preliminarily understand the status quo of space based on acquiring spatial target and environmental information previously, which is deeply understand the correlation and development trend of space situation, and comprehensively grasp the existing and potential influence of space situation on space activities.
As far as we can see, SSC has concluded that the complete process of product acquisition of spatial situation cognition can be divided into three parts: situation information acquisition, cognitive product generation, and cognitive product presentation.

Characteristic analysis of the SSC ability
Space situational awareness is not only the cornerstone of space security policy, but also the premise for the US to realize the militarization of space. The US regards space situational awareness as "the foundation of all space activities, the key premise of space control and the indispensable combat force". With the rapid development of space technology, the industrialization of satellite and ground equipment has become an irreversible trend in the future, while the constantly updated military concepts are also increasing the requirements for situational awareness. For some practical problems faced in the process of existing space situational awareness activities and based on concepts and technological trends such as "Mosaic warfare", "next Generation Space Architecture" and "autonomous system based on artificial intelligence", the following capabilities need to be further developed: (1) Highly dynamic.
Although the concept of Mosaic warfare is considered to be old wine in new wine, it still increases the complexity of target systems by several times of magnitude. Such high dynamic nature also forces spatial situational awareness to develop a high degree of dynamic planning capability.
(2) Strongly intelligence Space facility system is not static. They are designed, used and developed by human, who conduct thinking. As to say they are the expansions of human's behaviour and the expression of locomotive engineers' will in space domain. Thus, at the cognitive level, spatial situational awareness is also required to assist commanders in detecting deception, inferring intent, and quickly implementing actions within the decision cycle.
(3) Rapid reaction Commercial space mass production and manufacturing technology will completely change the research mode of space target and space environment, from effective high-precision control to autonomous manoeuvring ability. A large amount of space target data will pose a great challenge to the traditional mode which relies too much on human experience. Therefore, the autonomous capability of the system should be improved.

Technical Solutions for conducting SSC ability based on Knowledge Engineering
This paper aims at how to conduct the ability of SSC. In this part, there will be the detail technology solutions of conducting the SSC ability.

SSC-Process analysis
For multi-source heterogeneous data for space situational knowledge acquisition after the formation of a unified structured information, through these structured information form for the understanding of the whole space situational, and combined with the current information and historical experience for the space of the future projections on situational reasoning and behaviour, and auxiliary decisionmaking, eventually to guide action. As shown in figure 1, Figure 1. Conceptual display of spatial situation cognitive process.
Situation information acquisition, as the preliminary work, is the input link of product generation, situation presentation is the follow-up link of product generation, and product generation is the core link of situation cognition. Space situational cognitive product generation process based on the role of commander, starting from the analysis of demand, the key link include situational factors, situational information statistical description of expression, posture and reasoning for situation assessment and prediction of means, such as the construction of knowledge base and expansion, will eventually space situational cognitive aggregated into comprehensive space situational cognitive products one by one.

SSC-Entities analysis
Space situational needs for space environment of space target and integrates heterogeneous information through various channels, through the data cleansing after complete space situational data fusion, and is not restricted to the type of single point space target motion state of the space environment monitoring and controlling, but needs to be done on the basis of different level demand for space situational cognitive, Therefore, it is necessary to design multi-scale spatial situation model. This article through to new operational concepts and the development trend of space equipment, intelligent direction of cognitive analysis summed up the space state of high dynamic, strong, fast reaction ability needs wisdom, and then through the feasibility in theory to construct a multi-level and multi-angle in the cognitive model of space situational knowledge model, as shown in figure2, Figure 2. Logical classification of multi-scale spatial situation entity models.

Technical Solutions for constructing the ability of SSC
First according to carding summed up the high dynamic, strong, fast reaction ability of SSC needs wisdom, and then through the feasibility in theory to construct a multi-level and multi-angle in the cognitive model of space situational knowledge model, and through the diagram learning algorithm based on open source information of the target space situational knowledge fusion, And combined with neural network algorithm to build computing space situational knowledge and reasoning technology, realized based on the existing sensor data not only can be obtained as single motion law of space target within the scope of information, can also be based on open source intelligence and its associated target information to construct the overall space situational local cognitive ability of effective information, to verify the validity of the method are studied in this paper, The overall technical scheme is shown in Figure 3.  Figure 3. The overall technical scheme of SSC ability construction.
In the general technical scheme, through logical analysis the technical steps according to the knowledge engineering are classified and the need to complete the knowledge acquisition, knowledge representation, knowledge storage and knowledge application, the four stages, and each of these stages is influence each other interconnected, compatible, unified, knowledge fusion technology in stages can be classified into data level fusion, feature level fusion and decision level fusion, This paper plans by multi-source heterogeneous knowledge fusion technology to realize the unstructured static open source intelligence information, semi-structured and dynamic space target catalogic data, and of the integrated heterogeneous space target surveillance sensor data, this paper designs the multi-source heterogeneous knowledge fusion technology in the field of space situational architectures are shown in figure 4 below:

Conclusion
This paper discussed the significance of definition and graph model for the space situation cognition domain. With the rapid development of artificial intelligence technology, multi-source heterogeneous data fusion technology is also upgrading rapidly. In this paper, we can see that knowledge engineering can help the space situation cognition more efficient and conductive with the heterogeneous knowledge architecture for SSC proposed here. Therefore, in the face of massive distribution and explosive growth of spatial situation information in the future, there can be faster fusion and form multi-scale space situation cognitive results output. After the acquisition of low-level data based on sensor data, the space situation knowledge acquisition framework based on knowledge engineering can gradually realize the task and purpose of intelligent cognition of space situation.
In the future, we will continue to deepen the construction approaches and methods of space situation cognition ability under conflict information, and promote the wide application of multisource information fusion technology in the field of space situation awareness. Furthermore, the effective knowledge acquisition, knowledge understanding and knowledge reasoning capabilities of SSC will be further designed and realized through graph neural network (GNN), aim at more great significance to improve space technological level and space control power.