Kerbal Space Program – Rendezvous and Docking

Introduction

This guide is for anyone who has a decent understanding of how to play, yet still has trouble with rendezvous and docking maneuvers. It is an oft-repeated question on the forums, and both new players and veterans alike can find these maneuvers challenging to pull off. I’m not introducing anything new in this guide that can’t already be found in the Steam guides section, but hey, where one perfectly good guide may not click with someone, maybe the next one they read will. Learning to rendezvous and dock opens up many new areas of gameplay – Kerbal rescue contracts, in-space refueling, and 2 part landing missions (Apollo-style), to name just a handful. This guide will show one of the most basic rendezvous and docking situations, but will hopefully teach skills the reader can build upon to eventually accomplish any number of rendezvous and docking procedures. 
 
This guide will assume the reader knows how to reach a circular orbit around Kerbin, and is familiar with concepts and terms such as prograde/retrograde, knowledge of Navball markings, etc. 
 
Below are links to the simple orbiter and station used throughout this guide. 
 
 
https://steamcommunity.com/sharedfiles/filedetails/?id=2362577230 
 
 
https://steamcommunity.com/sharedfiles/filedetails/?id=2362901066 
 
 
 

Rendezvous

The first step to docking, is, of course, getting close enough to do so. For your first successful rendezvous, this guide will target Station 1 in a +/- 100km circular orbit around Kerbin’s equator, while launching Orbiter 1 from KSC. You are welcome to subscribe to and use the craft linked above, or you may have ships in orbit already in your game you want to dock with. The guide will reference Orbiter 1 as the intercept craft and Station 1 as the target; insert your own craft as needed. Either way, remember that it is critical that any RCS controls on your intercept craft be balanced around the center of mass. 
 
 
 
Bring up the center of mass graphic in the VAB, and either place one set of RCS controls right on it, or two sets an equal distance from center of mass. You must also keep in mind how the center of mass will change as fuel empties; with this particular craft it’s small enough it doesn’t become an issue. 
 
 
 
I like to launch when my target is just crossing the western shore of the peninsula KSC is on. Your target will pass overhead as you launch, putting you just behind it when you circularize. 
 
 
 
Assuming Station 1 is at a 100k orbit, aim for an apoapsis around 90k, and circularize your orbit when you get there. I like to set up a maneuver node for this, but it’s not entirely necessary. 
 
 
 
Once your orbit is stable, or whenever you find time, make sure you have clicked on your target in the map screen and selected "Set as Target", and that your controls indicator is displaying the intersect info by clicking on the third tab. Note the controls indicator in the lower left corner of the above screenshot. It should display two windows showing relative distance for Intersect 1 and Intersect 2. The navball shows that Orbiter 1 is still approaching its circularizing maneuver after launch. 
 
 
 
Orbiter 1 is in a 90k circular orbit, while Station 1 is in a 100k orbit. Lower orbits are faster than higher orbits, thus Orbiter 1 is now catching up with Station 1. If your target was behind you, you would want a higher orbit, allowing your target to catch up with your craft. 
 
 
 
If your launch was not perfectly 90 degrees, for either Orbiter 1 or Station 1, your orbit may be in a different inclination than your target. In this case, you will have to either burn anti-normal at the ascending node, or normal at the descending node in order to match inclinations. Mousing over the AN or DN symbols on your orbit will show how far off in degrees your orbit differs from your target. You want to shoot for 0.0, but .1 or .2 is often good enough as well. 
 
 
Once you have matched inclination with Station 1, set up a maneuver node behind Orbiter 1. Apply just enough prograde to bring your apoapsis up to the same average altitude of Station 1, in the example, about 100km. An intersect marker will appear somewhere opposite your orbit, bringing up Intersect 1 and maybe Intersect 2 info in the control indicator. 
 
 
 
Now that you have an intersect marker and distance displayed, you can fiddle with your maneuver node to try to get your intercept as close as possible. This may include click, hold, and dragging your maneuver node forward or backward along your orbit, or adding pro/retro/normal/radial inputs. Just watch the intersect distance displayed. If your input gets it closer, great, if not, take it back out. In the example, I had to time warp about a quarter of an orbit and drag the maneuver node up to my craft to get a good intersect. Obviously the closer the better, but anything within 5 km or so will eventually get you in docking range. Once you have that intersect, time warp to your maneuver node and burn the maneuver. Afterwards, you can use RCS to fine tune your intersect even further, if desired. Set SAS to, well, anything, then test each RCS direction with a short burst, by default H and N for forward/back, I and K for dorsal/ventral, and J and L for port/starboard. Watch the Intersect 1 window in the control indicator; certain RCS input will shrink your Intersect 1 distance, others will increase it. 
 
 
Once satisfied with your intersect, time warp to just before the intersect marker. At this point, your speed indicator above the navball should be set to Target. It should change automatically, but if not, click until Target is displayed. This will show the relative difference in speed between Orbiter 1 and Station 1. More importantly, it also changes the markers on your navball to also display this relative difference. 
 
 
 
Now setting your SAS to retrograde and burning until relative speed is 0.0 m/s will match your orbit with Station 1. Try to accomplish this precisely at the intersect 1 marker, which is as close as possible to your target. If you have followed the guide well to this point, relative speed should be less than 25 m/s. 
 
Congratulations, you have accomplished a successful rendezvous! 
 
 
 

Docking

 
 
Now for the fun part. Set your SAS to Target, or hold it there if you don’t have a level 3 pilot or probe core with Target Tracking. You can use your engines or RCS, but start closing the gap with a short burst, shooting for 1.5 m/s or so. Once you get the hang of it go as fast as you want, but for now, keep it slow and steady. Patience is key. Use RCS to keep the yellow prograde vector centered on the pink Target marker on your navball. 
 
 
 
 
 
Once close enough (100m or so), use the bracket keys [ or ] to switch vehicles and control Station 1. Click on Station 1’s docking port jr and select "control from here", then the docking port on Orbiter 1 and select "set as target". Set SAS on Station 1 to Target. This will point the docking port jr right at Orbiter 1. This method can be used to point any docking port, regardless of placement, at the incoming ship. Switch back to Orbiter 1 with a bracket [ or ] key. Because you set the docking port jr on Station 1 as the control point, Orbiter 1’s SAS, set to Target, will automatically target the docking port jr, without having to click on it and "set as target". 
 
 
 
At this point, your task is simply to keep your prograde vector on your navball centered on the Target marker, and make sure your docking port eventually touches at 1 m/s or less. This is most easily accomplished with RCS. The further away your initial rendezvous was, the more you will have to translate with RCS in order to stay centered on Station 1. If at any point you feel out of control, simply set SAS to retrograde and burn until relative speed is 0.0 m/s and start over, or hit N to use RCS to slow yourself to 0.0 m/s. Finally, it can be helpful to turn off RCS and SAS right before docking port contact. This will ensure that if you aren’t perfectly aligned, or if you bounce a little, those systems won’t fight the magnet on the docking port. 
 
Congratulations, a whole lot more of the game just opened up for you! 
 

I hope you enjoy the Guide we share about Kerbal Space Program – Rendezvous and Docking; if you think we forget to add or we should add more information, please let us know via commenting below! See you soon!