meetings - Space Flight Mechanics Committee

(from the scientific measurement standpoint). This paper investigates the effect of orbit
insertion error on the constellation's long term configuration and provides an initial
conjunction analysis for the un-controlled constellation.
9:00 AAS Collision Avoidance in Elliptical Formation Flying Based on Relative Orbit
13-354 Elements
Guo Zhong, Beihang University; Jianfeng Yin, Beihang University
In this article, a new collision avoidance model is developed based on relative orbit
elements (ROE). The propagation of the uncertainty estimate is studied using the unscented
transform (UT) method to remove the nonlinearities. The propagation equations of the
covariance matrix are derived. The collision probability model is established with the
consideration of J2 perturbation. The role of the ROE is highlighted on configuration design
and collision analysis. A new impulsive control strategy is proposed to reduce the
collision probability to an acceptable level. Finally the proposed methods are validated by
simulation through several typical examples.
9:20 AAS Trajectory Error and Covariance Realism for Launch COLA Operations
13-355 Matthew Hejduk, a.i. solutions
9:40 Break
The closing of satellite launch windows to mitigate collision hazards has been questioned
due to concerns about the accuracies of the predicted launch trajectories and accompanying
covariances. The present analysis examined thirty-seven launch events, comparing the
predicted trajectories to the associated launch telemetry in order to evaluate trajectory error
and covariance realism. The analysis found that these trajectories are more error-infused
than satellite ephemerides but that the associated covariances are realistic error statements.
Given that these covariances are appropriate to the trajectories they describe, these
products, if used correctly, can form an adequate basis for launch window closure.
10:05 AAS On-Board Estimation of Collision Probability for Cluster Flight
13-357 Michael Phillips, Emergent Space Technologies
Being able to detect and respond to potential collisions is a significant concern for
implementing satellite cluster flight. The accuracy and speed at which collision probability
can be estimated is a key factor in determining the minimum allowable closest approach
distance between any two modules, and thus the total size of a cluster. A method is
presented which takes into account both the state and state uncertainty to estimate collision
probability. Additionally this method generates a range of values in which the true
probability of collision will fall. The accuracy of this method verified through Monte Carlo
simulation.
10:25 AAS Autonomy Architecture for a Raven-Class Telescope with Space Situational
13-359 Awareness Applications
Ryan D. Coder, Georgia Institute of Technology; Marcus Holzinger, Georgia
23 rd AAS / AIAA Space Flight Mechanics Meeting Page 67