How to Plan Trajectories from Planets to Moons (or vice versa)

This tutorial will introduce you to the Rendezvous Maneuver Sequencer (RMS), which will help you send your vessel from orbit around one body into orbit around another within the same planetary system. This would apply if you're going from Kerbin to Minmus, or Minmus to Mun, or Kerbin to Mun, or Duna to Ike, etc etc.

This tutorial assumes you already have a craft in orbit. It will not discuss anything like optimal initial orbits, because it doesn't matter what orbit your craft is in for these steps to work. Your initial orbit will affect things like travel time and fuel use, but it will not affect the steps in this tutorial, so it is left as an exercise for the reader (or for another tutorial).

1. Open Mission Architect, open the default state for editing and import you craft orbit from KSP or SFS file.

2. After importing but before closing the Edit State window, right-click anywhere over the orbital properties and select the option to copy the orbital parameters to the clipboard.

3. Save the state and then go back to the main KSPTOT window and select Tools->Maneuver Planning->Rendezvous Maneuver Sequencer.

4. Paste the craft orbital data into the Initial Orbit Info section.

5. Use the selection box in the Final (Desired) Orbit Info to load up your target's orbital properties.

6. Either copy the Epoch of the Initial Orbit Info section and paste that into the Search Initial Epoch section, or enter in a later time from which point forward (not necessarily that exact time) you want to find a transfer orbit to your target.

7. Hit the Compute Rendezvous Maneuvers button and wait. While we wait, note that I suggest leaving the Search Window Length alone; if you don't find a good result in the default time-span just adjust forward your Search Initial Epoch time by 2hrs and try again. I'm also not going to cover the Search Parameter Weightings, but the basic idea is do you want to find the most efficient route that saves you fuel (DV) or time (TOD)? You can balance that as you want/need but for this example we're going to take the most efficient fuel route (default setting) and not care how long it takes us to get there.

8. Okay by now you have a plotted result. The DV Maneuver 1 Information box (middle one on the right) is the data you're looking for. Check your departure and arrival UTC times by copy/pasting them into the main KSPTOT window and, if they agree with your mission needs, copy the entire text of the window to an external text editor (otherwise you can't copy/paste from the RMS window into the Edit State windows in Mission Architect). If this trajectory doesn't work for you, you can either advance your Initial Search Epoch by two hours or just re-run the sequencer with the same values and you could end up with a slightly different better/worse result (make sure you save the first result, because it will be unrecoverable). The first result usually is fine as you just need something to start with, this will not be a final result.

9. Head back to Mission Architect and create a new Coast event. Select Go to UT and paste the Burn UT value from the text you copied from the RMS into the Universal Time text field. Be sure to uncheck the Opt box for now since the UT value will be outside the default entered range. Save the event.

10. Now re-open the event and change the type from Go to UT to Go to True Anomaly. This will convert the UT value to degrees and also give you a proper Revs Prior to Coast value. You can now re-check the Opt box as the values are back in range. Why not just leave it at UT? Way easier to optimize for TA - only 0-360 as opposed to coming up with the UT values for however many seconds, minutes, hours before and after the burn time. Why not just enter Burn True Anomaly straight from the RMS results? Because it wouldn't take into account how many revolutions the craft may have taken in orbit from the TA in the Initial Orbit Info epoch to the TA at the time of the burn.

11. Now then, we create a Delta-V Maneuver event after our coast event. Use the RMS results to enter in the DV values for Prograde, Normal and Radial. Take care to make sure the proper values go in the proper field (I've accidentally used the Total DV RMS result for the Prograde box before). Save the event.

12. Finally, create a Coast event with Go to Periapsis and set the Reference Body to your target. Save the event.

13. If everything went well, you should now be impacting your target body. Yay! Wait, no not yay. But from here you can use the Mission Optimizer to raise your Periapsis to something more reasonable for orbital capture after you arrive, as well as whatever else your mission parameters require. Since I don't know them, I can't offer any further advice.

If you are unfamiliar with the use of the Mission Optimizer, see the Kerbin to Laythe - Mission Architect Tutorial.pdf file that comes with KSPTOT.