Long term DSST behavior
Hi,
I am checking out the DSST module in Orekit 6 (git snapshot) and found that the very-long term behavior of DSST does not comply with other results. I compared against using the same forces using a normal numerical integrator in Orekit and using a free software tool STELA (http://logiciels.cnes.fr/STELA/fr/logiciel.htm) which both produce practically the same results. So, I suspect that there is an anomaly in the DSST implementation.
When I integrate an initial GTO orbit over a period of 200 years, after only 3 years, the DSST eccentricity deviates significantly from the alternative results (see attached graphs). The period of the oscillation of about 5 years seems to be off by 25% and the period of about 200 years seems to be missing altogether.
There is also a difference in the rate of change of the pericenter, which is slightly different between DSST and numerical / STELA integration runs. Since the eccentricity and pericenter are coupled, this affects the eccentricity as well, perhaps missing a resonance condition.
The forces in both systems are:
- Central body (earth, Cnm/Snm to order 5)
- Lunar and Solar (3rd body) gravitational effects
- No drag, no SRP
The orbital elements used are mean elements, but the difference between mean/osculating elements is negligible with respect to the differences shown between DSST and the numerical propagator.
Can you confirm that this is a bug and not a configuration issue and possibly provide a solution to this problem?
I've included the source I used to run the DSST/numerical orekit propagator, as well as the ephemeris generated by the STELA tool.
(from redmine: issue id 93, created on 2012-05-06, closed on 2015-01-12)
- Relations:
- relates #95 (closed)
- Uploads:
- DSST_simulation.java None
- None
- None
- None
- STELA.7z None
- None
- None