How do I capture around Laythe?

[ForgedDragon_]

Everytime I get close to it, I am going an insane 7000 m/s around it. I am kind of stumped on how do I get within an acceptable speed to capture.

[GunsForBucks]

Are you going the same way around Jool? CCW orbit?

[Quizzical]

Laythe is traveling at 3223 m/s relative to Jool orbit. As you approach Laythe on a good encounter with Jool, you'll be on an escape trajectory from Jool, and thus traveling over 4500 m/s relative to Jool. If your trajectory is tangent to Laythe's orbit while going in the same direction, then your speed relative to Laythe will be the difference of these numbers, or perhaps around 1400 m/s. If you're going in the opposite direction of Laythe, you could be going about the sum of these numbers, or 8000 m/s relative to Laythe. If you're not at all close to tangent to Laythe's orbit, you'll be going somewhere in between, such as around 5500 m/s relative to Laythe if on a path to hit Jool.

[ForgedDragon_]

Originally posted by GunsForBucks:

Are you going the same way around Jool? CCW orbit?

Well no. Probably was the issue.

[GunsForBucks]

Originally posted by Micheal Your Man:

Originally posted by GunsForBucks:

Are you going the same way around Jool? CCW orbit?

Well no. Probably was the issue.

Yeah I remember my first time entering Jool the wrong way. I was like... "OH that's not going to work... gotta remember not to do that again" ha ha

[Quizzical]

One time that you do want to approach in the "wrong" direction is if you're trying to get impressively large numbers when doing the grand slam passive seismometer science. Of course, that doesn't work for any body with an atmosphere, as it will burn up before hitting the surface, and the small ones make it easy to max the science regardless. But if you want to see that you've completed several million percent of the science possible, approaching a moon while orbiting in the wrong direction is one way to do it.

[JohnRando]

Relative speeds can be through the roof if your trajectory is not optimal, especially at these distances. Try to be as precise as possible with your initial burn, then do a correction burn somewhere along the way, and ultimately the best way to enter the Jool system is probably to get a gravity assist from Tylo.

And yeah, you need to enter in the same way the planets rotate, counter clockwise.

During your correction burn, use normal and prograde markers to change the time of arrival, which will change the phase of Tylo and let you have a nice assist.

[Jupiter3927]

Gravity assists are your best bet for large velocity changes near Jool.

[ForgedDragon_]

What happened was, I used a gravity assist by Tylo to get me captured around Jool. Problem was, that makes me go clockwise, as opposed to counter-clockwise.

[JohnRando]

Then you need to make a correction burn earlier (about 1/3 of the trip to jool) and set your apoapsis tangent to tylo, counter clockwise. The correction should take 5, maybe 10 DeltaV tops.

When doing the correction burn early, it is very cheap, and each m/s of DeltaV changes drastically your entry point in the jool system.

if you use "radial out" and "prograde in", you change the shape of the curve of the trajectory and by doing so you change the time of your arrival in the jool system. Same as lobbing a ball instead of throwing it hard. You reach the same point, but later. Later enough so the position of tylo is on the other side of jool. The "Good" side.

It takes some fiddling with the node to understand how it works. The key is doing it early on the trip.