Map & Tracking Station AP/PE are Dropping (Orbital Decay) When in Low Orbit of Some Planets/Moons

[Johny5]

While orbiting Mun around 15K my PE and AP constantly change as though I'm gently thrusting toward the ground. It stops at any level of time warp but reappears at normal time scale. Definitely no thrust or RCS active. 

Edited July 9, 2023 by Anth12
Changing title from being just the Mun

[SoulCandy]

26 minutes ago, Johny5 said:

While orbiting Mun around 15K my PE and AP constantly change as though I'm gently thrusting toward the ground. It stops at any level of time warp but reappears at normal time scale. Definitely no thrust or RCS active. 

Yeah my only game-breaking bugs appeared when trying to land on the Mun.

[magnemoe]

1 hour ago, Johny5 said:

While orbiting Mun around 15K my PE and AP constantly change as though I'm gently thrusting toward the ground. It stops at any level of time warp but reappears at normal time scale. Definitely no thrust or RCS active. 

Sounds like an KSP 1 bug I ran into from time to time, exit the game and restart tend to solve it. 

[Waifu Art Thou Romeo]

Same

[pickezzi]

I noticed this on my first attempt, amongst other things, like

• switching between KSC and ship arrests velocity completely, 
• time warp in map and then returning to normal speed can cause angular speed in the plane of orbit to go crazy, likely due to calculating part angular speed independently, between time steps changing from warp speed to normal speed)

time warp seems to put the orbit on rails and the orbital decay stops when returning to normal speed. it was reproduceable. 

These are fundamental bugs which the devs will absolutely solve very quickly. should report it in any case.

 

[Soda Popinski]

Same bug at 12,000 x 8000 meters.

[Pulstar]

I had mothership randomly end up on a crashing trajectory while I was busy flying/warping in the mun lander. Happened also after two reloads. It looked like the orbital origin shifted for it randomly after some time, I originally left it in a 30km circular orbit. Checked and deactivated the thruster just in case even.

[Ultimate Steve]

Can confirm my Mun orbits gradually decay as well.

[EimajOzear]

I'm thinking it's related to vessel attitude control after testing it. Manually control your orientation and the orbit drifts too. Turn off SAS after stabilising your vessel and the orbital drift/decay stops. 

It also seems like the game has a really bad time simulating the trajectories of non-active vessels like stage debris; a booster from a launch somehow escaped Kerbin's SOI before I did despite the booster being on an impact trajectory with Kerbin.

I noticed this same issue in KSP1 with larger craft when re-orienting them but didn't happen often enough for me to care. Now it seems to be the default in the current state of KSP2.

Edit: this seems to happen regardless of what celestial body you orbit, so I doubt it's a Mun-only issue.

Edited February 25, 2023 by EimajOzear
clarification

[didkodidko]

Decay and/or trajectory change happened on Mun and on IKE for me too.

[Gurkonier]

The Orbit changes dramatically around the mun, without any input.
I've turned SAS and RCS off and ensured, that all engines are deactivated, but my periapsis decreased about 3km in 1 minute.
This was in an 11km circular orbit. At higher altitudes the effect becomes less significant changing only by a few meters.

[wasml]

In a 9K Mun orbit. Went to the KSC and when I returned had a PE of 3K

[attosecond]

I had this also... circularized at 30km and saved. When I returned and loaded the craft, the PE was negative. Re-circularized and changed focus to another craft, and looking at the misbehaving one in map view it didn't have a trajectory line. Switched back, and the PE was negative again. 

[Wyleg]

KSP Version: 0.1.0.0.20892

Operating System and version: Windows 10

CPU and GPU models:  CPU -11th Gen Intel(R) Core(TM) i7-11700K @ 3.60GHz   3.60 GHz; GPU - GeForce RTX 3060

Description of the bug

Orbits decay. I have a  simple probe with no clipping parts at low orbit around Minmus. Thrust at 0, no force is applied to it. At 1x time orbit's PE decreases at a rate of ~10m/s. Entering and exiting time warp don't solve the problem, loading to another craft, VAB etc. and switchng back to probe does neither. It doesn't stop until PE drops to the ground.

Expected Behavior

Orbits of crafts in vacuum don't change without applied force.

Observed Behavior

Orbits decay by themselves causing crafts to collide with the surface.

Steps to Replicate

Create a probe, get it to Mun or Minmus low orbit, cut engines and observe. Maybe enter a timewarp and back to 1x tome speed and then look at PE readings.

Fixes / Workarounds (if known..)

None. Playing with PhysicsSettings.json seems to do nothing on that case.

A list of ALL mods.  If the list is long, please consider using a spoiler window.

No mods, vanilla

Other Notes / Screenshots / Log Files (if possible..)

https://drive.google.com/file/d/1a05pVnWPKIIYX2Qzp7__vHKgfPuU8xaN/view - video illustration

 

Comment:

This is very sad and renders the game borderline unplayable. Plz fix

Edited February 26, 2023 by Wyleg

[Radekpl]

I have same issue when flying to Jool.

[Malich]

Can confirm also occurring around Ike so this feels more like a global issue than location specific.

[Hecatonichosachoron]

I encountered this at Minmus.  After orbital insertion my AP, and PE continued to drift with no throttle or SAS active, changing by hundreds of meters

[Meta Jonez]

I've found that, with the Mun, any orbit with Periapsis below 20k is unstable.  On the downslope from Apoa to Peria, both elevations will decrease.  If, during that time, the Apoa falls below 20k, both will decrease in elevation after passing the Peria.  If the Peria is below 20k but the Apio is above, then on the upslope from Peria to Apio, both will increase in elevation.  If during that time that elevation brings the Peria above 20K, the orbit becomes stable and both numbers freeze.

Edited February 27, 2023 by Meta Jonez

[Abstractsolitude]

I found that getting your Kerbal to EVA and then re-boarding stops the decay without having to use time warp.

No idea why it works, but it seems to fix the issue

[Drakenred65]

I'm wondering if there trying to replicate 32  different lunar phenomena.

1 Such as our moons surprisingly "lumpy" and caused early low orbit craft to go off course and crash. 

2 is that there is an atmosphere and dust that can sporadically cause detectable drag to space craft.

 

3 

Spoiler

The kraken monuments are somehow involved. Not as likely but hey blaming things on them is a tradition around here.

[Vanamonde]

We have a sub for reporting bugs now, and this thread has been moved to it.

[AstroClef]

I documented this bug on all Non-Atmospheric Bodies:

 

Edited February 28, 2023 by AstroClef

[AstroClef]

This Bug is the same as this one here, even though it's not exclusive to the Mun: 

I've documented this bug on all Non-Atmospheric Bodies
Workaround is maintaining an orbit with Periapsis greater than the Sea Level altitude over your desired planet/moon found in the RED column

 

Edited February 28, 2023 by AstroClef

[Malich]

Additional info on my Ike orbit decay

• At 14km (approx. AP / PE) the orbit decays. This is the point at which the max time warp is x4
• At 45km (approx. AP/PE) the orbit does not decay. By this point I'm well into the point where I can warp at x10+

I'm not sure therefore if the bug is linked to orbital altitude or some factor of the time warp mechanism but one or other of these factors is at play.

[Mallysh]

I did not spend a lot of attention to my transfer vessel parked in a save mun-orbit at around 40.000m . I can only assume that it changed it´s orbit even when inactive and crashed into the mun, same as some empty boosters did earlier today. They kept changing orbit as I got rid of them at aprox. 100km above Kerbin instead of moving along the initial predicted orbit.

RIP Bob and Val

• KSP Version  0.1.0.0.20892
• Operating System and version  Windows 10
• CPU and GPU: AMD Ryzen 5 5600X; RTX3080 10gb 
• Description of the bug.  
  • Expected Behavior >> stable orbit of decoupled rockets and rocket parts
  • Observed Behavior >> orbits change without added energy >>see above

>>>>

Found a quicksave and saw the return vessel approaching the mun surface. The orbit did change! 

Next Bug (within that quicksave file) is that my lander after swiching to returnvessel and back startet to rise in altitude with shut off engines. No relative movement to ground, just straight up!!!