Satellite Dynamics About Tri-Axial Ellipsoids
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Satellite Dynamics Near Earth Asteroids↗
Engineering topics
Scheeres, D. J.
Publications and source records attributed to Scheeres, D. J..
Satellite Dynamics About Tri-Axial Ellipsoids
Current planning for the Near Earth Asteroid Rendevous (NEAR) mission includes and orbital phase about an asteroid. The current mission design stipulates Eros as the target asteroid.
NEAR near earth asteroid rendevous asteroid satell↗
Failure modes of reduced-order orbit determination filters and their remedies
Ways in which failure can occur in reduced-order, orbit determination filter, error covariance calculations are discussed. In the context of this article, reduced-order filters denote nonoptimal filters which include fixed levels of uncertainty in some parameters of the measurement models or in the spacecraft dynamical model which are not explicitly estimated in the filter equations. Failure is defined as an increase in the orbit determination covariance with the addition of data or as an unreasonable growth in the covariance with time, i.e., nonasymptotic behavior of the covariance. Some simple, known cases of failure are discussed along with their traditional remedies. In addition, more modern remedies are discussed which are currently under development at the Jet Propulsion Laboratory. The article first describes the known problems of reduced-order filters when they are employed for orbit determination, and their traditional remedies. Then, having defined these, the relevancy and desirability of the more modern remedies are made apparent.
Scheeres, D. J.↗
Particle Motion Near a Ring
The dynamics of a particle moving near a classical ring is studied under a Hill-type approximation. A classical ring is comprised of particles of equal mass arranged symmetrically about a massive central body, the particles having a uniform rotation rate.
ring stability ring growth Hill's Equation of moti↗
Satellite dynamics about a planet with a narrow ring
The dynamics of a satellite attracted by a planet with a ring are investigated. A single model for the gravitational potential of a ring is used which extracts the fundamental gravitational effects on a satellite. Analytical and qualitative results are presented in cases where the satellites orbit is in the plane of the ring and where it is out of the plane of the ring. As final results we present equations expressing the perturbation of a body from two body motion when the ring is narrow. These effects include the advance of the argument of the periapsis and the precession of the plane of the orbit (when the satellite orbit is not contained in the ring plane). Additionally, inequalities on the angular momentum of the satellite (for the planar case) are found which guarantee that the orbits are bounded and do not intersect the ring.
Scheeres, D. J.↗