CALIBRATION OF SEMI-EMPIRICAL ATMOSPHERE MODELS THROUGH THE ORBITAL DECAY OF SPHERICAL SATELLITES (original) (raw)
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An assessment of new satellite total density data for improving upper atmosphere models
Planetary and Space Science, 1999
The DTM series of atmospheric density models (Barlier et al., 1977; Berger et al., 1998) have been developed for atmospheric constituent representation and precise orbit computation. They are based upon satellite drag total density data which are implicitly averaged over one or more days.Our approach consists of refining the computation of the density model coefficients with more precise orbit computation, using the information contained in the tracking data. Satellite Laser Ranging (SLR) in case of Starlette (800 km) and GFZ-1 (380 km), Doppler-DORIS in case of SPOT2 (800 km).This has been verified by comparison of the new density values to Dynamic Explorer 2 (DE-2) measurements, as well as by precise orbit computation. In both cases, an improvement of a few percent has been achieved, showing the interest of the method.This study has been done in preparation for the new accelerometric mission CHAMP for which we prepare a new gravity field (GRIM5) using the orbit perturbation technique, as well as an improved density model, hence improving the drag modeling.
Journal of Physics: Conference Series, 2019
Artificial satellites in low Earth orbit have as main disturbance the atmospheric drag, which is a non-conservative disturbance that causes the satellite to lose orbital energy due to the friction with the air. Basically, the drag force is a function of the velocity, the local air density and the satellite’s constructive parameters. The air density is a function of altitude, longitude, latitude, geomagnetic index and solar activity. Solar storms are responsible for a wide range of terrestrial effects, especially in damage to telecommunications systems. Another relevant effect of solar activity is the variation in the volume of the atmosphere and consequently in the value of the air density for a given altitude, longitude and latitude. This work provides an initial approach, through simulation, in the engineering effort to deal with this disturbance.
In order to estimate the intrinsic accuracy of satellite reentry predictions, the residual lifetimes of 11 spacecraft and five rocket bodies, covering a broad range of inclinations and decaying from orbit in a period of high solar activity, were determined using three different atmospheric density models: JR-71, TD-88, and MSIS-86. For each object, the ballistic coefficient applicable to a specific phase of the flight was obtained by fitting an appropriate set of two-line orbital elements, while the reentry predictions were computed approximately one month, one week and one day before the final orbital decay. No clear correlation between the residual lifetime errors and satellite inclination or type (spacecraft or rocket body) emerged. JR-71 and MSIS-86 resulted in good agreement, with comparable reentry prediction errors (∼10%), semimajor axis residuals, and ballistic coefficient estimations. TD-88 exhibited a behaviour consistent with the other two models, but was typically characterised by larger reentry prediction errors (∼15–25%) and semimajor axis residuals. At low altitudes (<250 km), TD-88 systematically overestimated the average atmosphere density (by ∼25%) with respect to the other two models.