• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.1
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• pp.78-85
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• 2012

Space debris is the collection of objects in orbit around the Earth that were created by humans but no longer serve any useful purpose. Since the beginning of spacecraft launch in 1957, the number of space debris has been increasing. According to USSTRATCOM, the number of space debris which were bigger than 10 cm is more than 15,000. Recently there were two critical events: One is that China shot down their satellite using missile and the other is that two satellite, United States's Iridium 33 and Russia's Cosmos 2251, collided with each other. Thanks to these events, Space environment in which KOMPSAT-2 operates has become severer. This paper presents the analysis of the number of space debris which are close to KOMPSAT-2 and the maximum conjunction probability via minimum range. Especially, this paper makes it possible to continuously monitor the space debris that is possible to hit KOMPSAT-2 through the identification and analysis.

• Current Industrial and Technological Trends in Aerospace
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• v.9 no.1
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• pp.55-63
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• 2011

Space debris is the collection of objects in orbit around Earth that were created by humans but no longer serve any useful purpose. Since plenty of spacecrafts were launched in space after 1957, the number of space debris has been increased. According to USSTRATCOM, the number of space debris which are bigger than 10cm is more than 15,000. Recently two critical events were occurred. Which one was that China shot down their satellite using missile and the other was that t o satellite, Iridium 33 and Cosmos 2251, collided in space. Space debris environment in which KOMPSAT-2 is operating has been severe. This paper presents the status of space debris and international activity, and the comparison of conjunction assessment process between Korea Aerospace Research Institute and abroad satellite operation center.

• Journal of Astronomy and Space Sciences
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• v.29 no.3
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• pp.287-293
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• 2012

Satellite operating agencies are constantly monitoring conjunctions between satellites and space objects. Two line element (TLE) data, published by the Joint Space Operations Center of the United States Strategic Command, are available as raw data for a preliminary analysis of initial conjunction with a space object without any orbital information. However, there exist several sorts of uncertainties in the TLE data. In this paper, we suggest and analyze a method for estimating the uncertainties in the TLE data through mean, standard deviation of state vector residuals and covariance matrix. Also the estimation results are compared with actual results of orbit determination to validate the estimation method. Characteristics of the state vector residuals depending on the orbital elements are examined by applying the analysis to several satellites in various orbits. Main source of difference between the covariance matrices are also analyzed by comparing the matrices. Particularly, for the Korea Multi-Purpose Satellite-2, we examine the characteristics of the residual variation of state vector and covariance matrix depending on the orbital elements. It is confirmed that a realistic consideration on the space situation of space objects is possible using information from the analysis of mean, standard deviation of the state vector residuals of TLE and covariance matrix.