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Flight Dynamics systems have long been considered to be restricted fields inhabited by strange people performing highly complex computation on specific computers with specific languages. These systems did not really embed smoothly with the rest of the ground system. They use their own frameworks, their own GUI, their own database, and are often triggered either manually on dedicated computers or using very low level mechanisms like files dropped in shared folders or scripts wrappers. These systems are costly to maintain and clearly don't scale to today's needs with more demanding space missions and tighter schedules. The use of old technology implies skilled engineers are difficult to find and the few available have high hourly cost. Lots of work is to be done on interfaces because none of the new features brought by web technology is ever used. This paper shows a different approach for flight dynamics systems. It explains there is no reason such systems could not benefit from the current technology. The new development paradigms are mature and well known. They have proven useful on many critical fields and a tremendous offer of tools allows to improve code quality, testing, validation, traceability ... The open-source approach has also been time tested by now and is accepted for its unique features in critical systems and when long term maintenance are needed. The Orekit library (http://www.orekit.org/) is an implementation of these ideas. It is an open-source library freely available with a businessfriendly license and using state of the art models and technology. It demonstrates high performance operational products can be embedded in modern control centers to smoothly integrate complex flight dynamics functions right within the system. The project also shows the open-source approach is well suited for the flight dynamics field and that putting down some fences and sharing the code is a key feature for the success of such a library.

A multi-mission GEO satellite, COMS has three payloads including Ka-band communications, GOCI, and MI. COMS SGCS is the only system for monitor and control of the satellite in orbit. In order to fulfill the mission operations of the three payloads and spacecraft bus, COMS SGCS performs the following functions such as reception and processing of telemetry data via S-band link, planning and transmission of telecommand, tracking and ranging of the satellite, control and monitoring of SGCS equipment, analysis and simulation of the satellite, processing and analysis of flight dynamics data, and mission scheduling and reporting. By the proper functional allocations, COMS SGCS is divided into five subsystems such as TTC, ROS, MPS, FDS, and CSS. COMS SGCS is linked with MSC, KOSC, and IDACS for satellite related data exchange. The software in the COMS SGCS is designed using the object-oriented methodology and implemented using Microsoft C# .NET environment on Intel microprocessor based computers. The hardware in the COMS SGCS includes 13-m S-band mono-pulse Cassegrain antenna and RF/BB equipment. In this paper, development of the COMS SGCS is described with respect to system functional allocations, software and hardware design, system implementation, and system test.

KOMPSAT (KOrea Multi-Purpose SATellite) is an Earth observation program funded by Korean ministry of education, science and technology, and operated by KARI (Korea Aerospace Research Institute). KOMPSAT-2 was successfully launched into a circular, sunsynchronous orbit on July 28, 2006 with a three-year expected lifetime, and it is now normally operational in mission orbit without an anomalous event. The primary mission of KOMPSAT-2 is to provide panchromatic image with 1 meter resolution and multi-spectral image data with 4 meter resolution for various applications. Flight dynamics is one of the core activities in the operation of satellite mission for comprehensive orbital analysis and mission planning support as well as orbit data provision. This paper presents an analysis of KOMPSAT-2 orbit characteristics over three years in detail, including the operational orbit evolution, the performance of orbit determination and prediction, and the maneuver planning and its realization. Compared to KOMPSAT-1, the magnitude of the orbital variation is quite small thanks to the low solar activities, which leads to better performance in the accuracy of orbit determination and prediction. This paper also describes the automated orbit data processing system, which is developed by flight dynamics operation team in order to meet the operational needs. The routine operations on a daily basis, such as orbit determination, orbital parameter prediction, orbit evaluation against existing rules, planning for maneuver to be executed, and conjunction analysis with other satellites and debris could be a very demanding and time-consuming burden to the flight dynamics engineers. The automated system integrates all of the components of several routine processes which are necessary for daily flight dynamics activities, and it is now fully operational for KOMPSAT-2 mission support. This automation scheme considerably reduces the operational risk and cost by eliminating many repetitive processes and allows engineers to concentrate on non-nominal situations which require human intervention. Additionally, the stability and efficiency of the flight dynamics operations are significantly enhanced.

Over the past years it has been the standard approach to have two separate simulators for Flight Dynamics (FD) and for the Flight Control Team. Flight Dynamics are developing their FD simulator in order to validate procedures, data products, timelines as well as the performance and functionalities of AOCS related FD applications and systems. It is also used for training of their FD teams. The Mission Data System Section is responsible for the development of operational simulators in order to validate Flight Control Procedures, to verify specific items of the Ground Segment and to train the Flight Control Team. This paper will focus on the reasons behind the separation of these two simulators as well as explain the recent performance improvements which resolve these differences. Indeed, with the evolution of mission requirements and operational simulator technologies, a working group was set up prior to the Gaia simulator development, in order to assess the possibility of satisfying Flight Dynamics requirements using an operational simulator.