Improvement of Analytical Propagator
Abstract
Space debris has increased in recent years due to increased space activity and has evoked concern because of the potential damage it has shown to cause to launch missions. The accumulation of space debris can lead to Kessler's syndrome, especially in orbits of altitude less than 2000 km. As a part of these research contributions into space debris, JAXA and Kyushu University, Japan, have jointly undertaken research into Orbital debris evolutionary models to predict the evolution of the debris of different orbits. Amongst them is NEODEEM, which allows for the orbital debris evolutionary estimation of all objects orbiting around the Earth. An orbital debris evolutionary model consists of several components, the most important of which is an orbital propagator, which determines a body's motion over time. Orbital propagators are classified on the basis of integration methods. Amongst the different categories of Orbital propagators, the focus of this research is on analytical propagators, which can be further classified into a constant time step or a variable time step integrator. NEODEEM uses an analytical propagator with a constant time step of 5 days for debris estimation. A constant time step, however, has certain drawbacks. In the constant time step version of NEODEEM, the planetary position computations were done using the VSOP method, which had a high computational time. On the other hand, a variable time step allows for automatic adjustment of step-size, thereby allowing for incorporating planetary ephemerides equations developed by Simon et al. (1994), for the computation of planetary positions, thus allowing for faster calculations. The comparison of the results between the constant and the variable time-step propagator using the perigee altitude, showed a good correspondence, thereby allowing for the further continued usage of the variable time-step propagator. The compared graphs of the RAAN (Right Ascension of Ascending Node) and the inclination, between the VSOP algorithms and the ephemerides equations for orbits of altitudes lesser than 2000 km, using the variable time-step propagator indicated a good degree of correspondence. This confirms the ephemerides equation as being a reliable substitute for the VSOP method. Also, the compared Monte-Carlo simulations between the VSOP algorithms and the ephemerides equations using NEODEEM show a strong match, thereby increasing certainty to the fact that the variable time step propagator is capable of supporting the ephemerides equations and can be used as a potential substitute for the previous algorithm.
- Publication:
-
43rd COSPAR Scientific Assembly. Held 28 January - 4 February
- Pub Date:
- January 2021
- Bibcode:
- 2021cosp...43E2205M