meetings - Space Flight Mechanics Committee

compares the flown Dawn trajectory against the planned trajectory and expected maneuver
dispersions. Understanding the effectiveness of the maneuver design plan at Vesta is a key
component of planning for Ceres operations, the next destination for the Dawn mission.
14:30 AAS Dawn Orbit Determination Team: Trajectory Modeling and Reconstruction
13-346 Processes at Vesta
Matthew Abrahamson, NASA / Caltech JPL; Alessandro Ardito, ARPSOFT s.r.l.;
Dongusk Han, NASA / Caltech JPL; Robert Haw, NASA / Caltech JPL; Brian
Kennedy, NASA / Caltech JPL; Nickolaos Mastrodemos, NASA / Caltech JPL;
Sumita Nandi, NASA / Caltech JPL; Ryan Park, NASA / Caltech JPL; Brian Rush,
NASA / Caltech JPL; Andrew Vaughan, NASA / Caltech JPL
The Dawn spacecraft spent over a year in orbit around Vesta from July 2011 through
August 2012. In order to maintain the designated science reference orbits and enable the
transfers between those orbits, precise and timely orbit determination was required.
Challenges included low-thrust ion propulsion modeling, estimation of relatively unknown
Vesta gravity and rotation models, tracking data limitations, incorporation of real-time
telemetry into dynamics model updates, and rapid maneuver design cycles during transfers.
This paper discusses the detailed dynamics models, filter configuration, and data processing
implemented to deliver a rapid orbit determination capability to the Dawn project.
14:50 AAS Dawn Orbit Determination Team: Trajectory and Gravity Prediction
13-345 Performance during Vesta Science phases.
Brian Kennedy, NASA / Caltech JPL; Matthew Abrahamson, NASA / Caltech JPL;
Alessandro Ardito, ARPSOFT s.r.l.; Dongusk Han, NASA / Caltech JPL; Robert
Haw, NASA / Caltech JPL; Nickolaos Mastrodemos, NASA / Caltech JPL; Sumita
Nandi, NASA / Caltech JPL; Ryan Park, NASA / Caltech JPL; Brian Rush, NASA /
Caltech JPL; Andrew Vaughan, NASA / Caltech JPL
15:10 Break
The Dawn spacecraft was launched on September 27th of 2007 to consecutively rendezvous
with and observe the two largest bodies in the asteroid belt, Vesta and Ceres. It has already
completed over a year’s worth of direct observations of Vesta and is currently on a cruise
trajectory to Ceres. This data collection required careful planning and execution from all
spacecraft teams. Dawn’s Orbit Determination (OD) team was tasked with accurately
predicting the trajectory of the Dawn spacecraft during the Vesta science phases. This paper
will describe the OD team contributions to executing those phases.
15:35 AAS Dawn Orbit Determination Team: Modeling and Fitting of Optical Data at
13-347 Vesta
Brian Kennedy, NASA / Caltech JPL; Matthew Abrahamson, NASA / Caltech JPL;
Alessandro Ardito, ARPSOFT s.r.l.; Robert Haw, NASA / Caltech JPL; Nickolaos
Mastrodemos, NASA / Caltech JPL; Sumita Nandi, NASA / Caltech JPL; Ryan Park,
NASA / Caltech JPL; Brian Rush, NASA / Caltech JPL; Andrew Vaughan, NASA /
Caltech JPL
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23 rd AAS / AIAA Space Flight Mechanics Meeting