A study of empirical ionospheric models was undertaken to improve the accuracy of the ionospheric correction that is needed in satellite orbit determination. Our evaluation concerns the two most widely used empirical ionospheric models (Bent and international reference ionosphere (IRI)) and suggests improvements based on comparisons with satellite and ground‐based data. In both models, the topside electron density profiles decrease too sharply with increasing altitude. Our improved IRI topside formula compares well with AEROS satellite data and incoherent scatter measurements of the Jicamarca, Peru, radar facility. For the bottomside, a model for the effective parabolic thickness is introduced, based on the detailed IRI predictions. Recent progress in modeling the F2 peak altitude and electron density is reviewed. The increase in prediction accuracy compared to older F2 models is evaluated with Ionosphere Sounding Satellite b results (for density) and incoherent scatter measurements from Millstone Hill, Massachusetts (for altitude). The plasmaspheric electron content is also taken into account. Finally, results of a METEOSAT tracking exercise are used to check the ionospheric delays calculated with the different models. The changes indicated above were found to be helpful and resulted in an overall improvement.
Purpose -The purpose of this paper is to describe the current knowledge management activities at the European Space Operations Centre (ESOC), specifically in knowledge capture, sharing and preservation and focusing on the developed and adopted methods and on the results obtained related to the process of knowledge capture using video-recording of experts.Design/methodology/approach -The knowledge management activities undertaken at ESOC during the past years have been organized into four phases: preliminary study and investigation on knowledge management systems including a review of already existing initiatives; a pilot project within the Flight Dynamics area (a key technical domain within ESOC taking care of the orbit and attitude aspects for the satellite operations) with respect to the questions of knowledge transfer and its barriers; the definition of the ESOC knowledge management system; and the introduction of knowledge capture procedures.Findings -The inventory of the knowledge assets and the analysis of the knowledge coverage and criticality were essential to be able to identify the existing knowledge in specific areas and to perform a gap analysis. Through this analysis, it is now possible to identify those areas requiring improvement and to allow management to make reliable decisions for which areas the knowledge level should be increased.Research limitations/implications -With regard to the firm strategic behaviours, it seems particularly crucial to exploit all three dimensions of proximity, in order to guarantee openness and sustain innovativeness and competitiveness. Concerning policy implications, the local governments should address their actions to help and promote the openness of technology districts and the formation of technology clusters. With this aim, actions should be devoted also to sustain single local firms that are part of a technology cluster but not of a technology district. These, in fact, by increasing their competitive position, may generate positive externalities in the local area, fostering the diffusion and sharing of knowledge in the area and then, acting as knowledge gatekeepers for the whole area.Originality/value -The paper describes the implementation strategy of the knowledge management within ESOC. Based on this practical experience, guidelines can be derived for the implementation of a more general knowledge management system in the aerospace industry.
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