Gim J. Der, Der Astrodynamics, Andrew E. Kalman, Pumpkin, Inc
Keywords: Cubestas, autonomous orbit propagation
Abstract:
This paper describes the computational performance and implementation of the analytic Vinti algorithm for autonomous orbit propagation on GPS equipped Cubesats. Since the Vinti algorithm propagates directly with the GPS state vector (position and velocity vectors) as input, orbit propagation is straightforward, and unlike SGP4, conversion to TLE mean orbital elements is not required. Also periodic uplinks of the NORAD TLEs, which consume a relatively large amount of Cubesat energy and costly ground operations, are no longer needed. If the time between two GPS locks is 48 hours or less, then Vinti propagation is on average at least as efficient (accurate and fast) if not better than any existing analytic orbit propagator for space objects in any orbit regime. The Goddard trajectory program (GTDS) indicates that the analytic Vinti algorithm has no singularities, unlike other propagators. With the 2-Body and perturbed Kepler equations solved correctly, the Vinti computed state vector errors between GPS locks are less than two kilometers per day on average for Near-Earth objects. The implementation of the analytic Vinti Orbit Propagator (Vinti7 OP) into the Flight Software of the JPL-Stanford LMRST-Sat Cubesat by Pumpkin shows that very little energy (20 to 200 times less than a GPS fix) is consumed for the Vinti7 OP to compute an accurate state vector between GPS locks. Since the Vinti7 OP is accurate, fast, robust, and applicable to all orbit regimes, not to mention easy to use and implement, and consumes very little energy, it is hard to find a more efficient autonomous orbit propagator for GPS equipped Cubesats. In addition, ground processing of orbit determination, tracking and cataloging for cooperative Cubesats is greatly simplified.
Date of Conference: September 19-22, 2017
Track: Poster