Docking oddities in Kerbol orbit

[pylonog]

Has anyone tried docking in orbit around Kerbol/Sun? One of my ships ran out of fuel while transfer burning from Kerbin to Eve and is now orbiting Kerbol unable to maneuver so I sent a rescue craft but I noticed several oddities when trying to dock.

Firstly, getting an encounter was way more difficult than around Kerbin and had to be done in multiple stages, from getting a 100.000km encounter from far away, then going to 10.000km, 1.000km and finally slightly below 100km which I was unable to improve by means of RCS anymore (no direction of movement reduced the encounter anymore). So after a hefty 1200m/s burn at closest approach to reduce the relative velocities to zero I burned towards the target and managed to get a 2.6km encounter. At this point I thought that I got it but I was very wrong.

This is where things got really weird. Normally, when within a few km from a target, a marker starts to appear on the other ship, but not in this case. I could see the other ship pass by but there was no target marker as when docking in Kerbin or other body orbits. Furthermore, after reducing the relative velocity to zero again, the distance to target continued raising nontheless (Displayed Rel. Velocity stayed 0.0). Even thrusting towards the target, having my target-relative prograde-marker pointing directly towards the target, did help nothing, the distance to the target increased, but the relative speed stayed the same (so differently from what you usually get when burning directly towards a target in Kerbin orbit from too far away and messing up the orbits). Unfortunately, I then ran out of RCS fuel and had to abort docking since the ship did not have enough rotation authority without RCS.

I will try another attempt later with an improved ship but I wonder if anyone has ever tried docking a vessel in stellar orbit and noticed any oddities or if it was just a piece of cake. I expected the latter, especially after getting that 2.6km encounter, but was then struck by strange effects that I could not explain. Another oddity I noticed is that when zooming in on the system map, the ships were drawn quite off their orbital paths when zooming in far enough. So I wonder, was this my mistake? I docked countless times in Kerbin orbit and when something went wrong I could at least figure that out, but here I'm completely clueless.

I apologize if this is a duplicate but I looked for information regarding docking vessels in Sun orbits and could not dig up anything.

[Banbite]

F4 toggles the labels of vessels, that could be the reason why you didn't see any.

I haven't tried it but one reason why it could be so hard is that the increase in scale makes floating point errors much more prominent, maybe.

[NeoMorph]

Yes, I remember screaming BUUUUUUUUUUUUUUUUUUUUUUG when I lost the tags in my early days. Really annoyed me because I sucked at intercepts back then. The problem with stock KSP is that a lot of information that you need is hard to follow. The data panel in MechJeb go a long way to helping you decide when to burn and which direction to burn. Good telemetry is something that is very useful.

Losing those tags and not having Mechjeb is basically KSP on INSANE difficulty heh.

[pylonog]

I guess I must have hit F4 by accident. Didn't know that key up to now. Second mission was going much better, way less problems with jittering encounter markers and no oddities during the final approach. So to make up for the fuzz I caused, here's short mission report. Enjoy!

Launch of the Rescue Ship to refuel a spacecraft stranded on an orbit between Kerbin and Eve. Poor Danbro has been stuck in space for 3 years.

Getting rid of burnt out tanks.

I planned two full Kerbol rotations (so much for a quick rescue), plotting the escape course from Kerbin.

And away it goes!

Without any SAS or RCS, the predicted separation usually jittered by 100km at this point. This became more stable as I was approaching the encounter. Got it to 30km with multiple RCS corrections along the way.

Burning towards encounter orbit!

After some standard approach maneuvers, she finally appeared in sight.

Closing in, easy now...

Docked

All tanks refilled, it's time to say our farewell

Flying back home

Plotting final approach to Kerbin. Looks like we get a gravity assist from Mun.

Thanks Mun, you rock!

A hot re-entry to Kerbin

Getting ready to land. Things got very wobbly here, this is not a plane for flying around in an Atmosphere. Handles much better in space.

Just before landing

All went well and after being stuck in space for 6 ears now, Danbro Kerman seems happy to be back :-)

All in all an interesting experience and definitely a notch up in difficulty to docking in a planet or moon orbit. Maybe docking in Gilly orbit is next :-)