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Introduction

This article is a guide on how to dock two ships in orbit. Docking is one of the most difficult tasks in the game. It is like trying to land on a planet that's the same size as you and has no gravitational pull. Once you know how to do it, it becomes very simple, and after a couple of successful missions it will be routine. Mastering the art of docking allows you to do historic moon landings, build space stations, and long range manned vehicles. For the sake of simplicity, this guide will be divided into 4 phases: Launch, Closing Distance, Rendezvous, and Making Contact. Each of the 4 phases of docking have very distinct and unique workloads.

It goes without saying that in order to dock, you need a docking port on both vehicles. Unlike SR1, SR2 uses a single docking port for both male and female connections. For this guide I will be using a rocket I designed specifically for this. It has plenty of monopropellant to forgive any mistake, and enough fuel to establish an orbit at any altitude within low Droo orbit. The rocket can be downloaded Here.

Start by launching one rocket into orbit. For our purposes let's do an even 100km. Establish yourself into a perfect 100km/100km orbit and then load up another rocket on the pad.

Launch

For launch, proper timing is important to accomplish the mission in a reasonable time. We want to wait for the target ship to be nearby when we launch to avoid unnecessarily long wait times while our second ship closes distance. When you first load the second rocket, switch to Map view, and locate the other ship. Click on it and select the box icon to target it.

Wait until the target is approaching, but not directly overhead. We have to take into account that the target is traveling very fast and it takes a while to get there from a dead stop. In this case, I launched when the target was 400km away and it worked out very well, as you will see.

With our ship in a stable orbit, we now begin the next phase.

Closing Distance

After we have established orbit, we have to close the distance between us and the target. Depending on how far you are, this phase can take either 1 or 2 orbits (in this case since we launched so close), or it can take several hours of mission time. This phase is more waiting than it is work. All we have to do is adjust our orbit and let physics do the rest.

It's quite simple, if you are ahead of the target, you must increase your apoapsis (ex. 110km/100km). If you are behind, you must decrease your periapsis (ex. 90km/100km). Think of racecars going around a track - a car turning on the inside of the track will swing past a car on the outside of the turn. In addition to that, when we lower our periapsis, our velocity increases at that point, and likewise for the apoapsis; when we increase it, we slow down at that point. So, if you are ahead of the target like we are in this case, we want to do a small prograde burn to raise our apoapsis to allow us to slow down and let the target catch up. Yes, we technically need to speed up slightly to slow down.

How much? That depends on your distance. If you are several hundred km from the target, you may want to do up to 10km difference from the target's orbit. Go to Map view and look for the grey satellite icons that indicate the nearest approach. Due to a bug it might not show up... if this is the case you will have to tap around and find the nearest approach yourself. Once you've made your initial burn to establish a closing orbit (in my case I did 102km/100km since I was already so close), use time warp and just watch as your nearest approach drops lower and lower with every orbit. As your nearest approach gets below 100km, bring your orbit closer to within 5km, then 2.5km as you get down to 50km distance.

In my case I don't need to do much waiting. I already have a nearest approach of 5.3km right off the bat.

Rendezvous

Once your nearest approach is fairly close like this, you will want to make another brief burn to bring that nearest approach as close as possible. Pause the game, tap the orbit to open a Planned Burn, anywhere in the orbit. We will move it around as necessary to give us the lowest nearest approach.

Use all the directions of the Planned Burn tool, in combination with moving it around the orbit, to get the nearest approach as close as possible (<500m is ideal in this case).

In this case, I was able to get the nearest approach down to 164.5m. Unpause the game and execute the burn.

The automatic burns may not be perfectly precise, in my case mine left me with a 218.3m nearest approach as opposed to the 164.5m initially calculated. 218 is still plenty close so we'll take it.

On the bottom of the screen, tap the velocity to change it to Target. This is our velocity relative to the target ship. We also have a green arrow showing our relative motion and a blue arrowhead pointing towards the target.

Now that we are approaching our nearest approach, we need to activate Retrograde Hold and fire the engine to kill our relative velocity (reduce the velocity to 0). We are now essentially standing still in relation to the other ship. Click the button below Retrograde Hold to point the craft towards the target, then use RCS thrusters (translation mode) to push our ship towards the target. The green direction arrow will reappear, use the RCS to make it point towards the dark blue arrowhead, meaning we are now moving directly towards the target ship.

As if the act of docking wasn't hard enough, you also have to be wary not to fall into the dark side of the planet during the most crucial part of the mission, like I did! In my case I just brought my velocity down to zero so I wouldn't drift too far, then waited until we came back to the bright side. Once we came back to the light, I just proceeded back towards the target ship.

Now, you want to use the translators to position yourself directly in front of the target ship's docking port. Rotate yourself as needed. I suggest using Chase view, as with any other view you will easily get confused as to which way is 'up' on the RCS translators.

Once aligned, push yourself forward very slowly until you make contact with the other docking port.

Once contact is made, select one of the docking ports to monitor it's status. If it is not fully docking, you need to turn off the heading lock so it can move as needed to complete the dock.

Once docking has been established, be careful; your vessels may begin spinning. If this happens, disable and heading locks on both ships then use the Lock Current Heading on just one of them.

And that's all there is to it! Practice it a couple times and it will be like clockwork. Good luck, and I hope this helps.