The Evolution Of Highly Eccentric Orbits
Abstract
Highly eccentric orbits pose a unique challenge to the orbit determination process. These orbits may be perturbed by a broad spectrum of the natural forces which govern the motion of a space object and are difficult to model over long arcs. This work identifies the perturbation model improvements in the Draper R&D version of the Goddard Trajectory Determination System (GTDS) necessary to improve accuracy for a difficult orbit type known as the Molniya class orbit. Molniya orbits, with an eccentricity of approximately 0.7 and a period of slightly less than 12 hours, exaggerate the effects of eccentricity truncation in the J22 and tesseral resonance models. Additionally, these orbits may produce a steep reentry path and magnify the effects of atmospheric drag, particularly when the decay occurs near the minimum in the approximate 11 year solar cycle. This work analyzes the evolution of these orbits, from the mission or operational phase to the final degradation of the orbit. For the mission phase, there is an investigation of the primary source of remaining un-modeled error for these orbits, the truncation of the J(2) sub 2 term, and possible approaches for developing a working model of a closed form, second order, analytic solution for this term. For the primary focus of this work, the decay phase, a brief analysis of the modeling errors for various atmospheric effects is accomplished to create a functional representation of the process noise. Two variants of the error function are then used with a Kalman filter to develop an efficient algorithm for reducing observations for these orbits. The MSISE-90 atmospheric and a simplified lift model are also integrated into GTDS to more accurately model the decay phase. In addition, several utilities are created to efficiently analyze data characteristics of the observational data used for this work.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1998
- Accession Number
- ADA356381
Entities
People
- Jack D. Fischer
Organizations
- Massachusetts Institute of Technology