In this paper, a collision avoidance maneuver was sought for low Earth orbit (LEO) and geostationary Earth orbit (GEO) satellites maintained in a keeping area. A genetic algorithm was used to obtain both the maneuver start time and the delta-V to reduce the probability of collision with uncontrolled space objects or debris. Numerical simulations demonstrated the feasibility of the proposed algorithm for both LEO satellites and GEO satellites.
ABSTRACTdata. In addition, orbit prediction was conducted based on the orbit determination result with optical tracking data for 4 days, and the position error for the orbit prediction during 3 days was approximately 500~600 m compared to that of ESA's result. These results imply that the performance of the KARISMA's orbit determination function is suitable to apply to the collision risk assessment for the space debris.
A spacecraft placed in an Earth-Moon L2 quasi-halo orbit can maintain constant communication between the Earth and the far side of the Moon. This quasi-halo orbit could be used to establish a lunar space station and serve as a gateway to explore the solar system. For a mission in an Earth-Moon L2 quasi-halo orbit, a spacecraft would have to be transferred from the Earth to the vicinity of the Earth-Moon L2 point, then inserted into the Earth-Moon L2 quasi-halo orbit. Unlike the near Earth case, this orbit is essentially very unstable due to mutually perturbing gravitational attractions by the Earth, the Moon and the Sun. In this paper, an insertion maneuver of a spacecraft into an Earth-Moon L2 quasi-halo orbit was investigated using the global optimization algorithm, including simulated annealing, genetic algorithm and pattern search method with collision avoidance taken into consideration. The result shows that the spacecraft can maintain its own position in the Earth-Moon L2 quasi-halo orbit and avoid collisions with threatening objects.
The third sentence in Section III-B requires a reference which is considered important to implement the entire system, as follows.The role of the server is to turn on/off the equipment needed for ranging, to send ranging operation commands to the modem with the semi-active ranging capability [10] on time, and to store range measurements to its database.
Orbit determination (OD) for the geostationary earth orbit (GEO) satellite, Communication, Ocean and Meteorological Satellite (COMS), utilizes range information which is obtained by measuring the round trip time of a ranging signal and angle (azimuth and elevation) information to the satellite, collected from a single mono-pulse antenna in Daejeon, Korea. The accuracy of OD currently meets the operational requirement for the COMS, but more accurate OD may be needed for precise spacecraft maneuvering when the GK-2A and GK-B satellites, which will be launched in 2018 and 2019, respectively, are co-located with COMS on the geostationary ring. To find a method to improve the accuracy of OD, Korea Aerospace Research Institute (KARI) has recently implemented a semi-active ranging system in Daejeon and Weno, Micronesia whose baseline distance is approximately 4000 km. In this paper, the operating concept of the semi-active ranging system is described and the components of the implemented semi-active ranging system are presented. In particular, time synchronization between ranging stations is very crucial for successful range measurement. The paper explains the time synchronization method used in the system and investigates the time difference of the system. Then, the process by which the range is calculated is discussed. Finally, the paper evaluates the performance of the semi-active ranging system, through an analysis of the OD results obtained using COMS FDS (Flight Dynamics Subsystem) software and the commercial ODTK (Orbit Determination Tool Kit).
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