Tutorial: Laythe Aerobraking

Introduction

Going to Jool and want to save fuel without burning up in the atmosphere? You've come to the right place! This tutorial will show how to get directly to Laythe, aerobrake and return to an orbit around Jool. If you want to know how to get directly to Jool, click here.

NOTE: You cannot burn retrograde at periapsis to lower your velocity, you will not have enough time and will just fly past the planet at escape velocity. It is strongly recommended that you bring AT LEAST 1 heat shield with you or you can possibly burn up in Laythe's atmosphere.

Specifications

• Length: 15min - 1hr
• Difficulty: Hard
• For version: 1.0 to 1.2

Additionally, you will need a good understanding of orbital mechanics (see Tutorials section), angles, aerobraking and a lot of patience.

Getting To Laythe

NOTE: You MUST be orbiting Kerbol with an encounter with Jool for this to work. If not, click here to learn how to get to Jool and for a rocket design that is capable of reaching Jool.

The Setup

Start by selecting Laythe as your target. Time warp around your orbit until you are about ~100 days or so from entering Jool's SOI. Create a maneuver node a little bit ahead of you and change your camera to focus on Jool.

This is the hard bit. It requires a lot of fuel and patience.

Play with all your vectors until you get your Jool periapsis is at about ~20,000km from Jool's surface.

A successful encounter with Laythe

Now you have to use your vectors to move your orbit so it passes through Laythe's orbit in the correct spot, to get an encounter. Because Laythe is going counter-clockwise (to the left) in it's orbit, you must make your orbit intersect Laythe's orbit about ~45 degrees to the left of Laythe. So, if you draw a line from Laythe to Jool to the point where your orbit intersects Laythe's orbit, it should form about a ~45 degree angle to the left of Laythe (refer to image to the right).

If done correctly, you should see your "Closest Approach" arrows appear. Again, play with all your vectors to try to get the approach distance down. Once it it is close enough, the arrows will change into an intersect if done correctly. Just complete the burn and you will be on a path to Laythe!

Create a maneuver node a few hours before you encounter Laythe. Use the vectors to adjust your Laythe periapsis to a suitable aerobraking altitude (about ~48,000m for Jool orbit or about ~45,000m for Laythe orbit). NOTE: Your periapsis will drop a little as you descend further into Laythe's atmosphere, so plan accordingly. It is not recommended to go under 40,000m while aerobraking because you will be going very fast and most likely burn up in the atmosphere.

Time warp until you enter Laythe's SOI. Continue checking your periapsis regularly to make sure it is at your desired altitude. If not, just burn prograde or retrograde to change your apoapsis height. Point your ship prograde and prepare your heat shield (if you brought one).Timewarp a little until you enter Laythe's atmosphere. Your speed will be in between 6000m/s and 10000m/s when you nearing Laythe's atmosphere, so plan accordingly.

While in the Atmosphere

While you are in Laythe's atmosphere, try to keep your ship pointed at prograde and to not wobble around much. NOTE: Bigger ships will more likely move around more and turn over, so stay small.

Exiting the Atmosphere

If you are going to Jool, and you are in Laythe orbit, burn prograde to increase your velocity and escape Laythe's SOI.

If you are going to Laythe, and have an escape trajectory to Jool, burn retrograde to slow yourself down into Laythe orbit.

The End

There you go! You have now reached the orbit of Jool and/or Laythe! Good luck exploring the rest of the Kerbol System!