Shift in eccentricity and its mean value

[schaubh]

Hello to everyone!
I'm experimenting a strange behavior in the eccentricity profile during a simple orbital propagation in LEO.
I'm propagating the orbit considering both Drag and J70, starting from a LEO orbit with the following orbital parameters: [sma=6870km; ecc=0.000001; inc=92deg; raan=18deg; argp=20deg; theta=20deg].
However, Basilisk rises the following problems (see the attached plot where the blue lines represent the osculating elements while the red ones correspond to the mean parameters):
the initial eccentricity value is not correctly set but it has a shift up
the mean eccentricity computed with the function clMeanOscMap is not aligned with the osculating elements

Has someone else experimented the same issues? Is the eccentricity lower bound considered in Basilisk higher than the one I'm trying to set?

Thank you

[schaubh]

Hello Federica,

I think the issue you're seeing stems from the very small eccentricity value you are using. I don't think there's an eccentricity bound check at play here, so you might just be in the danger zone already. Also, I'm a bit surprised to see that the SMA is increasing by 300 km over a week under the effect of gravity and drag ! Are your dynamics only drag + J70 ?