Experiences in implementation and use of the square root information filter/smoother for orbit determination

The authors consider the orbit-determination square-root information filter/smoother (SRIF/S) component for TRACE, a large orbital analysis program. They review the TRACE SRIF/S design rationale and implementation effort from the perspective of a half decade of experience with its practical use, concentrating on the features that differentiate the TRACE implementation from others. This presentation is a largely anecdotal account of what factors shaped implementation decisions, how the system was tested, how is has performed in practice, what modifications have been made in response to requests from users, and how it stacks up today against the original goals and predictions