@InProceedings{KugaCarrGagg:2014:ImDrMo,
               author = "Kuga, H{\'e}lio Koiti and Carrara, Valdemir and Gagg, Luiz 
                         Arthur",
          affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and {Instituto 
                         Nacional de Pesquisas Espaciais (INPE)}",
                title = "An improved drag model for cbers orbit determination and 
                         propagation",
            booktitle = "Proceedings...",
                 year = "2014",
                pages = "1--17",
         organization = "International Symposium on Space Flight Dynamics, 24. (ISSFD).",
            publisher = "Johns Hopkins - Applied Physics Laboratory",
                 note = "{Setores de Atividade: Pesquisa e desenvolvimento 
                         cient{\'{\i}}fico.}",
             keywords = "ORBIT DETERMINATION, Satellite drag, Kinetic theory of gases.",
             abstract = "The CBERS-2B was the latest satellite of CBERS (China-Brazil Earth 
                         Resources Satellite) series, launched in 2007, and the follower 
                         CBERS-3 will be launched in late 2013. CBERS satellites have polar 
                         sun-synchronous orbit with an altitude of 778km, crossing Equator 
                         at 10:30am in descending direction, frozen eccentricity and 
                         perigee at 90 degrees, and provides global coverage of the world 
                         every 26 days. With such characteristics its orbit, besides 
                         gravitational forces, is mainly perturbed by the atmospheric drag 
                         and solar radiation pressure, amongst others (third body 
                         attraction, tides, etc.). However drag perturbation has shown to 
                         be most difficult to model in view of the need of accuracy for 
                         long lasting predictions. The current model for orbit propagation, 
                         used by the CBERS Control Center at the National Institute for the 
                         Space Research (Brazil), considers a constant value for the drag 
                         coefficient. In fact, the drag was estimated during orbit 
                         acceptance phase, which resulted a mean value of 2.7. This model 
                         was then frozen, with little variation allowed, and it is still 
                         being used for orbit determination and propagation in the INPE´s 
                         control center. Nevertheless it is known that the atmospheric drag 
                         depends on a multitude of different parameters with several 
                         sources, in particular the Mach number, the surface temperature 
                         and accommodation coefficients. In this work it is considered a 
                         model for the drag forces on CBERS based on the kinetic theory of 
                         gases, as proposed by Schaff and Cambr{\'e} (1961). The algorithm 
                         considers that the external satellite geometry is described by a 
                         boundary representation (b-reps) similar to that used in computer 
                         graphics such as OpenGL software pakage. Satellite surface is 
                         divided in a finite number of triangles, each one described by its 
                         vertex coordinates. Geometry is stored in an ASCII file using a 
                         subset of NASTRAN commands for the mesh description. Once the mesh 
                         is stored in memory, the forces and torques acting on the 
                         satellite (e.g. drag and / or solar radiation pressure) can be 
                         calculated by integrating it all over the external surface. The 
                         computation burden for computing drag forces with this approach 
                         is, of course, several times higher than the constant coefficient 
                         model. The main goal of this work is to compare this model with 
                         the quasi-constant drag coefficient results from the control 
                         center, in a long term basis, for instance one month at least 
                         (between maneuvers). Therefore it is able to retrieve eventual 
                         discrepancies and the orbit elements deviation can be promptly 
                         analyzed. The atmospheric properties were obtained from an 
                         analytical model proposed by Mueller (Mueller, 1982), based on the 
                         Jacchias 1977 model (Jacchia, 1977). Indeed any density model 
                         could be used as reference to draw the essential conclusions. The 
                         results have shown that there were some significant improvements 
                         in orbit prediction, when applied for long arcs (e.g. one month). 
                         Since computing time is not a very constraining requirement 
                         nowadays, it is expected that either the variable drag coefficient 
                         on-line computation or a corresponding suitable empirical 
                         parameterization (e.g. Ziebart, 2005) can be successfully applied 
                         in the upcoming CBERS missions.",
  conference-location = "Laurel",
      conference-year = "2014",
                label = "lattes: 1786255724025154 1 KugaCarrGagg:2014:IMDRMO",
             language = "en",
                  url = "https://dnnpro.outer.jhuapl.edu/Portals/35/ISSFD24_Paper_Release/ISSFD24_Paper_S8-4_kuga.pdf",
        urlaccessdate = "23 abr. 2024"
}