Bearings-Only Initial Relative Orbit Determination


A method for performing bearings-only initial relative orbit determination of a nearby space object in the absence of any information regarding the space object's geometry and relative orbit is presented. To resolve the range ambiguity characteristic of a single optical sensor system, a second optical sensor is included at a known baseline distance on the observing spacecraft. To formulate an initial estimate of the space object's relative orbit and its associated uncertainty, the angle measurements from both sensors are used to bound a region for all possible relative positions of the space object. A parameterized probability distribution in relative position that reflects uniform relative range uncertainty across the bounded region is constructed at two unique times. Linkage of the positional distributions is performed using a second-order relative Lambert solver to formulate a full-state probability density function in relative position and velocity, which can be further refined through processing subsequent measurement data in a Bayesian framework.


Mechanical and Aerospace Engineering

Keywords and Phrases

Data handling; Optical sensors; Orbits; Probability distributions; Uncertainty analysis; Bayesian frameworks; Initial estimate; Measurement data; Positional distribution; Range ambiguity; Range uncertainty; Relative orbit; Relative positions; Probability density function

International Standard Serial Number (ISSN)


Document Type

Article - Journal

Document Version


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© 2015 American Institute of Aeronautics and Astronautics (AIAA), All rights reserved.

Publication Date

01 Sep 2015