Watching this [animated GIF](https://commons.wikimedia.org/wiki/File:Animation_of_Akatsuki_trajectory_around_Venus.gif) of Akatsuky's orbit I noticed that it seems to "walk" around Venus.

Some orbital elements oscillate ~3-4 times a year, others drift and then slowly "step up to a new level".

According to NASA's [Venus Data Sheet](https://nssdc.gsfc.nasa.gov/planetary/factsheet/venusfact.html) the planet's $J\_2$ is about 250 times smaller than that of Earth, and this is not a low orbit.

**Question:** Why do Ataksuki's osculating eccentricity and inclination oscillate? Why do the Longitude of Ascending Node $\Omega$ and the Argument of Perifocus $\omega$ drift and step?

plotting script: <https://pastebin.com/GFn0dmuq>

[![Osculating orbital elements of Ataksuki](https://i.stack.imgur.com/IotMd.png)](https://i.stack.imgur.com/IotMd.png)