Tutorial: The Berry Maneuver
Virtually all tutorials and explanations of how to get to another planet or moon say first get into a similar, slightly smaller or larger orbit, then WAIT for your target to get close. This waiting can take years if you are going to another planet. The waiting is NOT NECESSARY. With the Berry Maneuver, it is very easy to align your Hohmann transfer orbit directly with your target the first time. The Berry Maneuver also makes gravity assists much easier. Any orbiting object encounter can be achieved simply.
This tutorial assumes familiarity with many important concepts in orbital mechanics:
- Hohmann Transfer Orbit
- Orbit Apoapsis and Periapsis
- Prograde and Retrograde burns
- Ascending Node and Descending Node
- Normal and Anti-Normal burns
- The Navball!
- Adding Maneuvers to your flight
All these concepts are covered in some fashion elsewhere in this wiki; they will be described briefly here.
The Berry Maneuver
The first step is to get into circular orbit. If you have not achieved orbit around Kerbal yet, another tutorial explains how. To circularize your orbit, raise your periapsis until it is about the same altitude as the apoapsis. To do so, burn prograde at the apoapsis. The orbit does not need to be perfectly circular. The purpose of circularizing the orbit is so you can start your Hohmann transfer orbit at any point. This step isn't strictly necessary but makes the next steps easier to see and easier to control.
Next, add a maneuver point to your orbit, and add a prograde burn (retrograde if the target has a smaller orbit) until the apoapsis of the new elliptical orbit just touches the target orbit (periapsis if the target is smaller). On the orbital map, you can tell the orbits are touching when two new icons appear on the target orbit, one white arrow pointing up and one white arrow pointing down. These show where you will be when you hit the target's orbit, and where the target will be. It shows more information, like how far you will be from the target, but we don't need that. All that matters is that you are not yet going to encounter the target.
