Illustrated guide to docking (2024)

After just getting something into orbit (and perhaps a Mun landing), the next big challenge for a new KSP player is how to dock in orbit. Here's a step-by-step illustrated guide for how to do so.

(There are various techniques... and plenty of other guides out there. This is just how I like to do it. I hope you may find it useful.)

The big picture

Docking

proceeds in four main steps:

Step 1: Rendezvous

Navigation tool: Maneuver nodes and map view
Control via: Main engine and throttle

The first thing you have to do is to send your ship on a course that will put it and the target in the same place at the same time-- or, at least as close as you can get with maneuver nodes.

I'm assuming here that you in fact

maneuver nodes (i.e. you've unlocked them by upgrading the tracking station), and also that you're familiar with how to use them.

I'm also assuming that you know how to set up a fairly good orbital rendezvous with maneuver nodes, i.e. one that will get you a closest approach within a kilometer or two. This is a big assumption: doing that is actually a significant challenge, and if you're a new player just learning how to dock, there's a pretty good chance you may not have mastered "orbital rendezvous with maneuver nodes" as a skill yet.

However, I'm not going into it here, for a couple of reasons:

But even though I'm not telling you how to do it here, I can show you what "good" looks like:

Exactly what your own situation will look like depends heavily on circ*mstances. But the important bit is that it's a close rendezvous. You want the closest approach to be as close as you can manage with the maneuver node-- no more than 2 km at most, preferably under 1 km. (In the above example, it's 0.3 km, which is pretty good.)

One more side note:

Step 2: Fine-tune the rendezvous

Navigation tool: Navball and map view
Control via: Main engine and throttle

Your eventual goal (in step 3, below) is to coast to a stop so that you're parked right next to the target (as in, just a couple of dozen meters apart).

Chances are, however, that unless you're either super lucky or an ace at maneuver-nodes, the rendezvous that you set up in Step 1 above will only get you to within a few hundred meters at best-- perhaps a kilometer or two. You'd like to be closer than that when you match velocities, since your final approach (using RCS) will be very slow, just centimeters per second, and you don't want to have to do that for a kilometer or more.

So the way to solve that is to make minor course adjustments with light touches on the throttle of your main engine, using the navball for guidance. Here's how:

First things first: Make sure navball is in "target relative" mode

Once you get close to the target, you don't care what your orbital velocity is. You only care about your velocity relative to the target. Chances are, the navball is probably in "Orbit" mode when you're in orbit (the game does that automatically, unless you've manually tinkered with it).

Normally, when you approach your target within 60 km, the navball will switch automatically to "Target" mode instead of "Orbit": this causes your prograde/retrograde markers to indicate your target-relative velocity rather than your orbital velocity, which is what you want. It looks like this (note the "Orbit" or "Target" indicator at the top of the navball):

...Typically, it will do this automatically for you and no action is required on your part. I only bring it up because it's possible this might not happen, and you need to make sure that the navball is in "Target" mode, or nothing after this point will make any sense. You can change the mode manually by clicking on the label. This will toggle the navball between Orbit, Surface, and Target modes.

Why this fine-tuning step is needed

As you get within several kilometers of your target, your navball will start to look something like this (again, make sure your navball is in target mode):

This looks pretty good: your marker (target

) is pretty close to your marker (target

). The fact that these two are close together means that you are heading almost directly towards your target.

However, the key word here is "almost". If you just coast towards your target and do nothing, you'll see the marker slide farther and farther away from the marker, like this:

That's because you're not heading directly at the target. Unless you got super lucky (or are an ace) with the original maneuver node, your closest approach is likely to be at least several hundred meters away from the target. This means that without any course corrections, you're going to go past it, and the target will slide off the side of your navball in the same way that someone standing beside the road slides off to the side of your windshield as you drive past them.

Therefore, you need to adjust your course when you get close by, so that you are sitting right next to your target (and not a kilometer away) when you come to a stop relative to it.

What to do

When you get reasonably close to your rendezvous (say, when it's 1 minute away, which you can see in the map view when you mouse over the intercept marker), start the process.

What you're trying to do is to move your marker so that it's precisely centered on your marker (i.e. so that you're heading directly at the target). To do this, start by lining up your navball so that your crosshairs, , and are exactly lined up in a straight line, like this:

Note that the marker is exactly on a straight line in between the navball crosshairs and the marker.

Why do we do this? Well, firing your engines "pushes" the marker away from the center crosshairs on the navball. Since what we want to do is move the marker onto the marker, then by lining the navball up this way, it will "push" the marker in the direction we want it to go.

Once you've got it lined up, gently throttle up to move the marker. How much throttle you need will depend on your ship's TWR and how big your target-relative velocity is. So just keep a careful eye on the navball, gently throttle up, and be ready to kill the throttle immediately when things line up.

As your engine burns, you will see the marker drift towards the marker, like this:

When the two markers line up perfectly, cut throttle. (Don't worry if it's not pixel-perfect; all that matters is that it's better than it was. If you're off by a smidgeon, what will happen is that as you get closer to the target, the two markers will drift apart again, and you can do this correction maneuver again. Repeat as needed.)

Prograde fine-tuning (if you end up too slow while still far away)

In the preceding discussion, we did all our fine-tuning while thrusting close to . I recommend this because it kills two birds with one stone, thus saving dV: not only does it fix our heading to get a close approach to the target, but it also helps kill some of our velocity (since we'll need to reduce that down to zero in the next step).

However, it could happen that you end up approaching too slowly while still far away: i.e. your target-relative velocity is very low while you're still at a long distance. In such a case, fine-tuning in the prograde direction is an option. Details in spoiler.

Spoiler

Maybe you got overzealous in the next step and killed your velocity while you're still far away from the target. Or maybe your maneuver-node rendezvous has you at a very slow closing speed with the target. Or maybe you're just impatient. In other words, you could have a situation like this:

In a situation like this, you can do fine-tuning in the prograde direction instead of retrograde, so that you accelerate towards the target. The important thing to remember is that thrusting "pushes" the marker away from the navball crosshairs, but it "pulls" the marker towards the navball crosshairs.

Therefore, to do a maneuver like this, you flip around so you're pointing close to . You line things up so that the marker is on a straight line in between the navball crosshairs and the marker, like this:

Then you gently thrust, which will "pull" the marker towards the navball crosshairs (and therefore towards the marker). Cut the engine when they get lined up perfectly, like this:

Now you're headed straight at the target. You can proceed to Step 3 now. (Or, if you think you're still going too slow towards the target, you can line up on your crosshairs and thrust some more.)

I recommend using this prograde technique sparingly: it wastes dV, since you're using fuel to increase your target-relative velocity, which you'll then need to spend even more fuel later to cancel out when you get close to the target.

Step 3: Kill relative velocity to target

Navigation tool: Navball and camera view
Control via: Main engine and throttle

This is the easiest part of the process, since there's little steering involved. All you have to do is slow down to a stop in the right place.

As you approach the target, line up your navball so that you're pointing perfectly retrograde (i.e. the marker is centered perfectly in the crosshairs-- again, make sure your navball is in target-relative mode, not "orbit"). If you have a level-1-or-better pilot, or if you have a HECS-or-better probe core, then this is easy: just choose the "hold retrograde" SAS button (red arrow in the illustration below). But if you don't have that convenience, just do it manually.

As you approach the target, the marker will want to drift away from center; if necessary, you can do more correction as described above in step 2.

Reduce your speed gradually as you approach the target. If you wait too long, you'll overshoot; if you start too soon, you'll go too slowly and it takes forever to close the distance. I find that a handy rule of thumb is "stay 30 seconds away from intercept": switch to map mode and mouse-over the intercept marker, which will give you a timer countdown to closest approach. Thrusting to slow yourself down will increase the time-until intercept. Just keep that at 30 seconds until your speed gets down to whatever you're comfortable with (I usually go for around 10-15 m/s), then switch back to camera view and you can eyeball it the rest of the way.

When you get really close, slow yourself to a stop, 0 relative velocity. You're now parked right next to the target-- if you got things lined up well up to this point, you'll be very close, just a few meters away, like this:

Step 4: Prepare to dock

Navigation tool: Navball and/or camera view
Control via: reaction wheels only

First, get roughly lined up. We need to get the docking ports at least approximately lined up (facing towards each other).

If possible, the easiest way to do this is to switch briefly to the target ship (using the [ ] keys) and rotate it so that it points its docking port towards your ship, then switch back and rotate your ship appropriately. This is a lot faster and easier than flying your ship around the target to get in the right spot, which is tedious.

(Sometimes that might not be an option, if it's not practical to rotate the target-- for example, if your target is a huge, massive, asymmetric space station with random stuff docked all over it. In that case you just gotta fly your ship to where it needs to be.)

Next, set your target and control-from to the two docking ports.

Right-click on the target docking port and choose "Set as Target":

Right-click on your own ship's docking port and choose "Control from Here":

Now, get your orientation precisely aligned. That is, you want the axis of your docking port and your target's to be precisely parallel. (They may be laterally offset from one another for now, but we'll deal with that next). There are a couple of ways to do this:

Option #1: Use a docking-alignment mod. My personal favorite is Navball Docking Alignment Indicator. It's very minimalistic, uses no screen real estate, stays out of my way when I don't need it. What it does is this: whenever your target is a docking port, it adds a red icon to the navball showing your alignment relative to it. When that red icon is perfectly centered in your navball cross-hairs, it means you're perfectly aligned for docking. So if you have this mod installed, all you have to do is rotate your ship to center that red icon. Your navball would then look like this:

...all you need to do is to rotate your ship to center the red icon in the navball crosshairs.

Option #2: Just eyeball the orientation. This is doable but less convenient. Not only do you generally have to monkey around with different camera angles, but it also becomes a royal pain in the dark, since you can't see what you're doing unless the ships are lit up. This is what I did for the first several months (and several hundred dockings) in KSP, until I got fed up and switched to option #1. Really, that mod ought to be part of the stock game, IMHO.

Either of the above two options will work. For the remainder of this discussion, I'll use screenshots that have the mod present, not only because that's how I do it when I dock, but also because it makes the screenshots much easier to understand.

Next, turn on fine-control mode. This is caps lock by default (on Windows machines; I think it may be different on Macs). Doing this will turn your control indicators at bottom-left from

red to cyan, like this:

...The reason why you do this is described in another blog post, but what it boils down to is that it makes your RCS thrusters smarter so that it's easier to control your ship.

Next, activate RCS (press R). There, we finally get to use our thrusters!

Step 5: Dock!

Navigation tool: Navball and/or camera view
Control via: RCS thrusters

Okay, now the fun part.
Thrust gently prograde using your RCS thrusters until you get your speed up to 0.2 or, at most, 0.3 m/s. Slow slow slow. Your ship is now heading directly straight ahead. However, that's not quite right yet, since the target is offset to the side by a bit. We need to apply some lateral thrust in order to get us heading in the right direction.

Initially, your navball might look something like this:

How to read this:

So now you need to use your RCS thrusters to correct that. Use your lateral thrust (IJKL for up, down, left, right) to nudge the marker to where it needs to be. You want to arrange it so that the marker is directly on a straight line between the marker and the center crosshairs, like this:

...What this means is that as you drift towards the target, you're also drifting sideways so that you're lining up with it. As you get closer, you will see the slide towards the center crosshairs. As it gets closer to the center, you can nudge the marker inwards, too (using RCS), still keeping it lined up:

When the marker reaches the center of the crosshairs, use RCS to center the marker there, too.

You're now all set up perfectly for docking:

Now all you have to do is just let it coast until docking completes.

Ta dah!