The Effect of Flares on GPS Satellite Orbits

Robert C. Anderson

Abstract:	The purpose of this paper is to estimate the magnitude of the effect of large solar flares on GPS satellite orbits. This is done by computing the change in acceleration brought about by a change in the solar model parameter due to the flare intensity by using the model of Cappelari, Velez and Fuchs, with cross-sectional areas and reflectivity values for block I and II satellites from Fliegel, Gallini and Swift. Satellite orientation and orbital parameters are assumed. Then, the equation of relative motion (Newton’s law of gravitation and 2nd law) is used to compute the orbital position of the satellite for various flare durations with and without the perturbing acceleration from the flare. The resulting second order differential equations are solved by using a fourth order Runge-Kutta technique. The resulting differences in position are tabulated for various flare durations. The report concludes that by using a solar constant only; errors larger than 1 cm may result due to a change in solar radiation pressure in the event of This paper seeks to find the magnitude of the effects of solar flares on the Global Positioning System (GPS) Space Vehicle (SV) orbits. In particular, it is desirable to know whether the algorithms used in NIMA’s precise ephemeris determination system should be adjusted to account for periods of increased solar flare activity. Solar flares produce a surge of energy which will increase the amount of solar radiation pressure (SRP) on the orbiting body. A simple SRP force model will be examined and the resulting change of position in a GPS SV’s orbit will be calculated for large solar flares.
Published in:	Proceedings of the 54th Annual Meeting of The Institute of Navigation (1998) June 1 - 3, 1998 The Adams Mark Hotel Denver, CO
Pages:	297 - 301
Cite this article:	Anderson, Robert C., "The Effect of Flares on GPS Satellite Orbits," Proceedings of the 54th Annual Meeting of The Institute of Navigation (1998), Denver, CO, June 1998, pp. 297-301.
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