A fast, accurate, and smooth planetary ephemeris retrieval system

Precise trajectory simulations typically require an ephemeris retrieval system, i.e. some mechanism to identify planetary body states and orientations at given times. However, the ephemeris systems most commonly used throughout industry and academia are, by design, general in their capabilities and application. Here, we introduce a new system called FIRE (Fast Interpolated Runtime Ephemeris) that is designed for custom trajectory applications that favor speed and smooth derivatives. The new system minimizes the overhead associated with ephemeris calls through the use of archived splines, a runtime ephemeris (stored in random access memory of the computer), and batch processing routines. Further, our approach naturally provides first and second time derivatives for a small additional computational cost. The derivative capability is particularly attractive for optimization and targeting where smooth and accurate derivatives are important. Relative performance comparisons with the Jet Propulsion Laboratory’s Spacecraft Planet Instrument C-matrix Events ephemeris system show typical speed improvements of approximately two orders of magnitude (250 times) for various state and orientation calls. Performance comparisons for high fidelity trajectory propagations are also considered and a factor of 70 in performance increase is achieved for typical cases. The new tool has potential value to any high precision application or software requiring fast, accurate, and smooth ephemeris data.