Satellite Dynamics about Small Bodies: Averaged Solar Radiation Pressure Effects
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Satellite Dynamics about Small Bodies: Averaged Solar Radiation Pressure Effects D. J. Scheeres I Abstract The effect of the solar radiation pressure force on a spacecraft orbiting a small body (asteroid or comet) is analyzed for the general case when the small body is in an elliptic orbit about the Sun and the spacecraft is in a relatively close orbit to the small body. The effect of this force is parameterized in terms of the spacecraft mass, spacecraft surface area exposed to the Sun, the small body mass, and the small body orbit about the Sun. Constraints and general results on orbit dynamics are presented and discussed for the averaged solar radiation pressure effect. These solutions are seen to be integrable and a function only of the small body true anomaly. Four families of stable, frozen, Sun-synchronous orbits close to the small body are found, all for the case of elliptic motion of the small body about the Sun. Such orbits have applications for extended station-keeping at a small body or for mission operations when the solar radiation pressure effect is large. Speci fic results for the NEAR spacecraft at asteroid 433 Eros and the Rosetta spacecraft at comet Wirtanen are given.
Introduction The growing interest in asteroid and comet science has motivated the space science community to plan and propose numerous missions to these small bodies. Consequently, the analysis of orbital motion about such bodies has become an issue of interest as well. One of the many important perturbations that a spacecraft is subject to when in orbit about comets and asteroids is the effect of the solar radiation pressure acting on the spacecraft itself. Analyses made for the case of planetary orbiters are no longer valid as the central attraction of a small body can be very small, leading to fundamentally di fferent effects. This problem has been analyzed by the scientific community; in particular see Hamilton and Burns [1] for a review and discussion of this problem applied to small dust particles and natural satellites. The definitive result in the study of the solar radiation pressure (SRP) effect is given in the paper by Mignard and Henon [2]
'Department of Aerospace Engineering, The University of Michigan, Ann Arbor, MI 48109-2140. E-mail address [email protected].
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where they show that the averaged effect of the SRP when in orbit about a body is, in fact, integrable and they give explicit solutions for that case. In this paper we give a brief review of those results and apply them to the case of a spacecraft orbiting about a small body, such as an asteroid or comet, isolating particular results of interest to an orbital mission. Additionally, we make some notes about the effect of the SRP forces on the NEAR spacecraft at the asteroid Eros and the Rosetta spacecraft at the comet Wirtanen. Neglected in this paper are several effects. First, it is assumed that the SRP force will not strip the spacecraft away from the small body, a situation which may occur. See Scheeres, 1995, [3] for a discussion of t
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