meetings - Space Flight Mechanics Committee

9:00 AAS Refining Space Object Radiation Pressure Modeling with Bidirectional
13-374 Reflectance Distribution Functions
Charles Wetterer, Pacific Defense Solutions, LLC; Richard Linares, University at
Buffalo, State University of New York; John Crassidis, University at Buffalo, State
University of New York; Thomas Kelecy, Boeing LTS; Marek Ziebart, University
College London; Moriba Jah, Air Force Research Laboratory; Paul Cefola,
University at Buffalo, State University of New York
High fidelity orbit propagation requires detailed knowledge of the solar radiation pressure
(SRP) on a space object. In turn, the SRP is dependent not only on the space object’s shape
and attitude, but also on the absorption and reflectance properties of each surface on the
object. These properties are described by a surface bidirectional reflectance distribution
function (BRDF). This paper demonstrates that for space debris whose interactions with
electro-magnetic radiation are described accurately with a BRDF, then hitherto unknown
torques account for rotational characteristics affecting both tracking signatures and the
ability to predict the orbital evolution of the
9:20 AAS Essential Thrust Fourier Coefficient Set of Averaged Gauss’ Equations for
13-375 Orbital Mechanics
Hyun Chul Ko, University of Colorado at Boulder; Daniel Scheeres, University of
Colorado
9:40 Break
By applying an averaging method to Gauss’s variation equations, the perturbing
accelerations acting on a spacecraft can be presented as a function of 14 Thrust Fourier
Coefficients(TFCs). Time rate changes of mean orbital elements related to these TFCs are
analyzed and the representation of these thrust coefficients as a function of change in orbit
states is studied. We find both minimum coefficient solutions as well as minimum norm
solutions of TFCs. The minimum set of 6 TFCs provides the finite basis representation of
arbitrary orbital maneuvers that allow us to dynamically interpolate between states across
an unknown maneuver.
10:05 AAS Fast Interpolation of High Fidelity Gravity Fields
13-321 Nitin Arora, Georgia Institute of Technology / NASA / Caltech JPL; Ryan Russell,
The University of Texas at Austin
An update is provided on the development of a new interpolated gravity model that
efficiently trades memory for speed. The model utilizes the weighting function interpolation
method originally proposed by Junkins et.al, and a new adaptive selection of local
polynomials. The acceleration and higher order derivatives are smooth and are calculated
naturally as the gradient of the fitted geopotential. The new polynomial selection algorithm
reduces the memory requirements by upto 40% over the prototype model. As an example,
fitting the GGM02C field requires 1.4 Gb of memory while achieving over 300x speedup
over the Pines spherical harmonics implementation.
23 rd AAS / AIAA Space Flight Mechanics Meeting Page 73