an open-source vision for flight dynamics

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. I. Traditional architecture light Dynamics systems are an essential part of ground systems for space applications, just like those many other essential parts as control center, mission center, tracking stations … Two main architectures have been used in ground systems. The first one considers Flight Dynamics as a self-contained subsystem exchanging data with control center (AOCS and propulsion telemetry, maneuvers commands …), mission center (ephemeris, operational forecasts, visibilities …) and tracking station (localization measurements, pointing data). The second one embed Flight Dynamics within the control center, which acts partly as a data gateway with the other systems. In neither case is Flight Dynamics tightly integrated with the other parts. A general interface is used to shield all computation programs from the rest of the ground system. F