Spining round (like a record!)

[peewee69]

Hi all!

Just wondering if anyone knows why my space station in orbit around the Mun refuses to stay still. I put the thing upright, engage SAS and as long as I don't switch back to space centre or another vessel it'll remain in that position no problem. However, if I switch to another craft for a while, when I return to my space station it has drifted away from it's upright position?

Does the Mun have weird fluctuations in it's gravity field or something? I have also noticed that leaving my Mun lander in orbit will result in the ship spinning with an accelerating force. Surely this defies the Newton's law of motion? Or is there a very thin atmosphere around the Mun which creates tiny amounts of drag?

[Snark]

So, no, there are no weird fluctuations or trace atmosphere or anything like that.

In my experience, the game has always been a bit cavalier about maintaining orientation of ships between active sessions.  Would help if you had a screenshot-- it's not clear what exactly you mean by "upright" in this context.

If you've noticed that your ship starts to spin in an accelerating fashion when you're not touching the controls, then there are a few possibilities:

• Possibility #1:  You've got the "trim" set.  This is a cryptic, well-hidden feature that is intended to help people fly airplanes in certain situations, which lots and lots of people don't know about, and probably most people never use on purpose, but is easy to engage accidentally without realizing it, since there's no visual feedback that it's on.  Essentially it means you have some torque engaged even when not touching controls.  You can turn off the trim by hitting alt+X, try that and see if it fixes the problem.
• Possibility #2:  You've got a joystick or similar controller plugged in, and it's leaning over or something, and generating a continuous control input that you're not realizing.  Hey, don't laugh, I've seen more than one person post with this problem.  It happens. 
• Possibility #3:  You're having a visit from the kraken, i.e. experiencing a "phantom force" resulting from some game bug (possibly involving clipping or the like).

Just a few possibilities that come to mind.

[swjr-swis]

• Possibility #4 (for the part about accelerating force): You're witnessing a pretty recent bug of the game, where orbits are no longer completely stable and decay slowly but steadily for no apparent reason, even around bodies without an atmosphere. (We're speculating whether it's proof of existence of the Aether, or dark matter being more massive than we calculated.)

I concur with Snark though: the game never really honoured ship orientation between sessions (just like it doesn't honour your last SAS setting). A ship without any acceleration at all should simply keep its last orientation.

[Reactordrone]

8 hours ago, peewee69 said:

Hi all!

Just wondering if anyone knows why my space station in orbit around the Mun refuses to stay still. I put the thing upright, engage SAS and as long as I don't switch back to space centre or another vessel it'll remain in that position no problem. However, if I switch to another craft for a while, when I return to my space station it has drifted away from it's upright position?

 

This will also depend on what you consider to be upright. If you point your station normal/anti-normal it should stay in that orientation (rotating around its axis as it orbits). Any other orientation (radial or prograde) will appear to change as you orbit unless you have SAS direction hold on and you're focused on the station.

[peewee69]

Thanks for the replies.

For clarification, by 'upright' I mean pointing at normal (in my equatorial orbit this means north), which, as Reactordrone points out, should maintain that orientation.

I have no joystick, so not that. I'll try turning the trim off later (as Snark suggests) and see if that works. However, quite few weird orbital decays have been appearing in my game since 1.1, so it is probably connected to the bug that swjr-swis mentions.