Spacecraft Orbit Control using Air Drag

Paper number

IAC-05-C1.6.10

Author

Dr. Giovanni B. Palmerini, University of Rome "La Sapienza", Italy

Coauthor

Prof. Silvano Sgubini, University of Rome "La Sapienza", Italy

Year

2005

Abstract

To design the orbital control making correct use of environmental perturbations is an important skill in order to have more reliable, less expensive, simpler space missions. Generally, passive control alone could not match highest performances granted by active techniques, but anyway there are  classes of missions where such a behavior can be considered as sufficient, and related design and manufacturing savings make this choice appealing. 

This work focuses on very low altitude missions, where the air drag is by far the strongest perturbing force. Deployment and stowing of small extendable surfaces, varying spacecraft cross section, can purposely change the orbit. The amplitude of these changes is of course depending on the density, as well – or therefore, if the solar bulge is considered – on the anomalies along the orbit where these actions take place. These effects could be especially exploited while considering the case where a defined geometry between two spacecraft has to be kept, as in the case of formation flying, or a fixed orbital slot (the set anomaly-time) has to be maintained by a single spacecraft.

Building on this background, this paper aims to analyze the orbital dynamics associated with the opening and closing manoeuvres of the extendable surfaces and to define correct control strategy in order to acquire a defined orbital slot. The introduction of a switching function solves for the simpler formulation of this problem (du Toit, Palmerini). More complicated formulations, including the drag variability, do require different approaches, for which a recently presented (Carter and Humi) analytical solution of the classical Euler-Hill equations including drag as a function of the orbital radius is quite useful. Moreover, the approach to the strategy identification problem using a numerical tool as the genetic algorithms is considered. The goal is to define a class of orbits and missions, and a related range of altitudes, where such a control exploiting air drag could provide a satisfying dynamics behavior.

Abstract document

IAC-05-C1.6.10.pdf

Manuscript document

IAC-05-C1.6.10.pdf (🔒 authorized access only).

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