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# How to get closer to tha target ship ? ( while the orbit is the same as the target's )

## Question

As the title says, i can't figure out how to do that, though i've watched multiple videos about it. Here's a screenshot to describe it better :

As you can see, there are 2 ships : one's mine, and the other is from a mission ( Gregdour ). The problem is that we both spin along eachother, so we'll never 'regardevouz' as it should. I tried burning in all the axes directions, from up and down to the mid-left and left and mid-right and up-left etc. It will reduce the relative speed ( 4123 m/s ), but it will break my orbit.

So how do i do it ? ( btw, please don't use rocket science terms like retrogade and anti-normals and other stuff like this -> colors ( i'm dumber ).

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Welcome to the forums !

if your orbits are nearly identical and the ships are very close, just burn towards the target ship.

if your orbits are nearly identical but the 2 ships are in completely different positions around the planet (like one on each side of the planet) then you must either slow down to let the target catch up with you or go faster to catch up with target. (makes sense right ?)

To slow down, you need to go in a higher orbit, because higher orbit=>slower orbit. To go higher you have to burn prograde, wich is the green marker (not the crossed one, the other). Make sure your orbit is circular and just a bit above the target's. It will then catch up !

To go faster and catch up, do the exact opposite.

Timewarp until the ships are very close and then execute the inversed procedure to bring back your orbit to normal. Here you go !

don't be afraid of terms like prograde, retrograde, normal, radial... it's fairly easy to remember, it will get you good grades in physics (it did for me) and it's the first step towards becoming a badS KSP master

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did you do the rendezvous tutorial? try recreating it's starting situation ... as said, do an orbit that is slightly bigger or slightly smaller. then just follow what you learn in the tutorial

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First picture is broken.

Second, those terms are common jargon, refusing to learn them is really crippling yourself.

You have matched orbit, that is a good first step. Now you need an intercept. Unless you are already close enough for direct burns to be useful (5 km or lower) you need to use orbital mechanics to get closer. Orbital mechanics are a little counter intuitive for a neophyte.

Is your target ahead of you? You need to slow down. Slowing down will lower your Pe (low point of orbit). You will now actually go faster at that Pe than before (more than you slowed down) and reach the same point in your orbit sooner (your orbital period is shorter)!

Is your target behind of you? You need to speed up. Accelerating will raise your Ap (high point of orbit). You will now actually go slower at that Ap than before (more than you speed up) and reach the same point in your orbit later (your orbital period is longer)!

Both scenarios will bring your closest distance markers (the pair of orange or pink arrows on your orbit in the map) closer until you overshoot. If you overshoot, just follow the opposing advice but ease up a little bit. The more you change the orbit, the more you close/open distance.

I can't stress how important it is to learn the jargon. Once you start understanding the concepts you can do really fun stuff. For example, I never need to match orbits before rendezvous. From any orbit, I can crash my ship into another with just two burns in one orbit! With a third, I can rendezvous instead of crash. I'm thinking in terms of prograde and normal vectors for these manuvers.

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If two things are in the same orbit they'll be going at the same average speed so will not get closer. You need to have one in a slightly different orbit so that one orbits faster than the other and they close up. If you're patient it doesn't need to be much, just put one orbit a kilometre or two lower than the other and wait.

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One more thing:

- get close through orbital mechanics, that doesn't need to be 5km, but that depends on the speed of your movement. If you're at a low periapsis of a long orbit. moving very fast, then the encounter must be very accurate. If you''re at the outskirts of Kerbin SOI, 50km is still fine - all depends on your speed.

- burn towards Target marker on the navball, get some 10m/s, maybe less.

- USE RCS CONTROLS to chase the prograde marker into the middle of the target marker. J,K,L,I - see how pressing them affects the prograde marker, then make it move right into the target marker. As you get close, it will be escaping, keep chasing it back in.

- and brake early enough. I just crashed my ship into an asteroid... literally a minute ago...

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4km/s relative speed sounds they are on opposite sides of the orbit...

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4km/s relative speed sounds they are on opposite sides of the orbit...

That's what I was thinking, sounds like they're going in opposite directions

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Hello,

Thx. alot for the info given - considering this the best answer And for the picture : http://postimg.org/image/w882xdaqj/

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If your relative speed is that high, I think you're going the wrong way. You'd have to turn around.

Cheapest way to fix that is go faster like you're going to minmus, ride the orbit until you're as high as you can go, then burn backwards. Either that or restart and launch the other way.

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Yep, totally, same orbit, opposite direction.

Instead of Minmus, use Mun for an Oberth effect turning you around. But nevertheless the amounts of dV to be used are so silly high, you're much better off just deorbiting near KSC, then launching again in the right direction.

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If your relative speed is that high, I think you're going the wrong way.
Not necessarily. If you and your target are on opposite sides of the planet you will see high relative velocities.

Checking is easy though. Hover your mouse over the AN/DN marker. Close to zero degrees is good. Close to 180 is going the wrong way.

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Oh yeah, after getting less than 10m far away from the target, I just figured out i don't have the necessary equipment to dock the ship... gr8

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( btw, please don't use rocket science terms like retrogade and anti-normals and other stuff like this -> colors ( i'm dumber ).

You're in good company - Gemini IV had the same difficulties.

The whole 'aim at target and thrust' isn't going to work unless you're already on top of each other and have, relatively, little different in velocity.

Wemb

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... those terms are common jargon, refusing to learn them is really crippling yourself.

What he said. But also, you know that you can't really talk about 'up' and 'down' in space? But pro and retro grade (and normal, antinormal, radial and anti-radial) are the nearest things you've got, and the only way you can describe what direction you're going.

Basically - Prograde means 'forward' and retrograde means 'backward' (based on the direction you're moving, *not* the direction you're pointing). Radial and Normal are directions that are based on your direction of travel compared to the body you're orbiting - radial is the direction toward the center of your orbit (e.g. if you're flying around Kerbin, it points to Kerbin) - anti-radial is the opposite direction.

Normal is a bit more difficult - but if you get your right hand, point the first finger in the direction you're flying, point your middle finger to the center of kerbin, and stick your thumb up in the air, then the thumb is the the 'normal' direction - and antinormal beng the opposite.

Wemb

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Oh yeah, after getting less than 10m far away from the target, I just figured out i don't have the necessary equipment to dock the ship... gr8

Does the contract say you have to recover the other guy's ship? If not, then you don't need to dock. Just get reasonably close to it (say within about 200m), then switch to the stranded ship, EVA the Kerbal, and have him fly over to your original ship. Land that, leaving the stranded ship in orbit.

This does require, however, that your own ship has an empty place for the rescued Kerbal. Either your ship has 2 or more pods (at least 1 of which is empty) or is a probe with an empty pod.

HELPFUL HINT: When you first switch to the stranded ship, before you get the Kerbal out of it, rename the ship to debris (using the icon button---the actual text name doesn't matter). This will keep you from confusing the stranded ship for one of yours later when you look at the map.

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thx for the tips all you ya Yes, i do have to rescue him, but i don't have any vessel with 2 spaces, and i hate going in space without a pilot to activate the ASA... waiting to research one and then i'll get that creep down

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I second this - it's a pain to get a bunch of rescue missions and having to jump back to the ships to work out which ones are empty and wihch aren't. Thought next I do this, I'm going to see if I can do something fun with the KAS explosives packs.

Wemb

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Very old video I did on docking... (when close but need to get closer in orbit. For rendezvous it's a different method)

https://youtu.be/szJOoX7h77w

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Actually I never rename ships. I can tell from map view whether a ship is rescued or not with it not being active ship... Click the ship. "Switch to" - already rescued. "View in tracking station" - my next rescue mission

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I just "terminate" all the junk that has no further use from tracking station. Frees up some CPU resources when the game unloads the debris.

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