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Re: [Orekit Users] 0.1 deg Inclination bias?

"Hammel, Gregory (ASC/CSA)" <gregory.hammel@canada.ca> a écrit :


Hi Greg,

This is my first post to this list, so I would just like to start by thanking everyone who contributes to this project. Its an incredible resource.

I am trying to use Orekit for mean state generation for stationkeeping using DSST. To that end I want to take in a vector from an external source (in this case, STK) read it in, propagate it, including manoeuvres, and then use DSST to get pre and post-maneouvre mean states. If I take a J2000 vector and provide it to DSST to get a mean state, I get an inclination of 97.75 deg. However, if I first propagate that same vector and then pass it through DSST I get an inclination of 97.65 (in this case, without any manoeuvres).

I'm using the same methods as outlined in the "MasterMode.java" tutorial for my "pre-mean" propagation, but I've modified it by including solar and lunar grav and DTM2000 drag.

Can anyone explain why there is a 0.1 deg shift in the inclination? I can provide the code if it helps.

If you convert starting from a single state vector, and change from
one propagator to another one, you can have this sort of problems.

I'll suggest to look at the propagation.conversion package and
at the associated test cases to do the conversion from a full
time range (say one or two periods) instead of a single state
vector. What this package does is a fitting, trying to ensure
the trajectories stay close to each other, in a least squares

Hope this helps,


Greg Hammel

Gregory Hammel
Analyste de la dynamique de vol
Contractuel SED a division of Calian Ltd. Utilisation de l'espace
Agence spatiale canadienne / Gouvernement du Canada
gregory.hammel@canada.ca / Tél.: 450-926-5138

Flight Dynamics Analyst
Consultant SED a division of Calian Ltd. Space Utilization
Canadian Space Agency / Government of Canada
gregory.hammel@canada.ca / Tel.: 450-926-5138