Unstable Munar Orbits?

[Bloodbunny]

As some of you know, orbiting the Moon in real life is quite difficult. http://science.nasa.gov/science-news/science-at-nasa/2006/06nov_loworbit/

This is due to the differing densities which make up the Moon's crust. But something like that is probably beyond the scope of KSP right? Well consider my findings on a flight today.

I launched a satellite carrying an ISA Mapsat dish to map the Munar surface in preparation for an Apollo style landing, placing it into a perfectly circular orbit of 150 km. In order for the Mapsat to do its thing, I left the game running and went to bed. Upon waking up, I checked the game, and found that the orbit had gone completely bonkers (for lack of a better term,) decaying its PE to 96 km, while its AP had gone to 226 km. The flight is still going, and I will monitor it until it crashes. I have telemachus installed, so I'll post a graph later if it shows anything of value.

Bug, feature, or noobish observation that I'll get flamed for?

[rryy]

Maybe you left the engine running at a low throttle.

[Stazi]

Does the satellite have MechJeb on it or any form of ASAS? I've noticed lately that MechJeb/ASAS can cause the AP/PE to fluctuate slightly due to the ship rotating around while trying to maintain a specific heading.

[UmbralRaptor]

Was (5x or higher) time warp on or off? you were not using warp (or in physical warp), there are still floating point errors that slowly alter orbits.

[Bloodbunny]

Engine was not running at all, and I didn't have warp going. Since I was just going to bed, I left it at 1x just to make sure it didn't crash the game or somesuch. I did have ASAS on, so that may well be the culprit. I have turned it off, and will see if the orbit continues to change.

It is most likely coincidence, but I did find that my PE of 96 km was almost directly over the biggest crater on the Mun.

[whiterafter]

This happened exactly to me with ASAS at about 3-4x time acceleration but at Minmus. My thing would drop 5 m every 3 oribts and I was orbiting at like 7,800 m.

[Bloodbunny]

Yep, its definitely ASAS causing it. Doesn't make sense that it would, because it provides no thrust, but it does. Bummer, if Squad had actually modeled Lunar Mascons I would have been jaw droppingly impressed.

[Conarr]

Spank the gerbils in the ASAS and get back to mapping!

[samstarman5]

Spank the gerbils in the ASAS and get back to mapping!

'SCOFF' Gerbils... 'SCOFF'

They use Chinchillas in the ASAS. Gerbils go in the RCS thrusters.

[Conarr]

'SCOFF' Gerbils... 'SCOFF'

They use Chinchillas in the ASAS. Gerbils go in the RCS thrusters.

Sorry, I sit corrected.

[rosenkranz]

I've had something like this happen during Mun landings. Setup for landing and then timewarp to 20km and my landing prediction pulls in 10km.

I've seen this if I time warp at all during landing approach. The orbit decays every time i come out of timewarp.