meetings - Space Flight Mechanics Committee

Feb 11, 2013 Kauai Salon 3
SESSION 7: ORBITAL DYNAMICS NEAR SMALL-BODY
Chair: Dr. Steve Broschart, Jet Propulsion Laboratory
13:30 AAS Comet Thermal Model for Navigation
13-259 Pedro Llanos, University of Southern California; James Miller, Consultant; Gerald
Hintz, University of Southern California
We implement a numerical model to analyze the thermodynamics that can be used for
navigation and orbit determination of future space missions to small bodies. Unlike past
models that use a spherical homogeneous model, our model includes the real non-spherical
shape of asteroid 433 Eros as an example. The surface temperature map is expressed as a
function of latitude and longitude directions for different initial isothermal temperatures.
The lack of spherical symmetry is modeled including the long and short term temperature
variations as a consequence of the orbital and spin axis rotations of the body.
13:50 AAS Multiple Sliding Surface Guidance Applied at Binary Asteroid Systems
13-261 Julie Bellerose, Carnegie Mellon University SV / NASA ARC; Roberto Furfaro, The
University of Arizona; Dario Cersosimo, University of Missouri
Proximity operations at binary asteroid systems involve higher degrees of complexity due to
added perturbations. In this paper, we adapt a Multiple Sliding Surface Guidance (MSSG)
algorithm developed for close proximity operations at a single asteroid, and extend its
applicability to binary asteroid systems. The advantage of using MSSG is that no trajectory
is needed to be computed offline as the commands use the spacecraft accelerations directly.
We show simulations of a two-sphere and sphere-ellipsoid binary systems. The velocity
cost and associated transfer times show to be minimal.
14:10 AAS ZEM/ZEV Guidance Approach for Asteroid Touch-and-go Sample Collection
13-262 Maneuvers
Brian Gaudet, University of Arizona; Roberto Furfaro, The University of Arizona
The Osiris mission to 1999 RQ36 requires the spacecraft to touch down to the asteroid’s
surface to collect samples. Importantly, the final descent to the asteroid’s surface must be
unpowered in order to avoid sample contamination. Our proposal uses ZEM / ZEV
guidance with selected waypoints to reach a point 30m above the desired landing site. The
constraints imposed by the optical navigation system result in a small velocity error at the
initiation of the coasting phase, which results in unacceptable landing accuracy.
Nevertheless, we show that mission requirements can be met by hovering at the final
waypoint.
14:30 AAS Estimation of Asteroid Model Parameters using Particle Filters
13-264 Brian Gaudet, University of Arizona; Roberto Furfaro, The University of Arizona
23 rd AAS / AIAA Space Flight Mechanics Meeting Page 35