launching to Duna

[Joe.L]

This is a very straight black and white question that seems pretty obvious the answer but I am really struggling...How do you launch to Duna?

 

I have got into orbit then done an escape burn and find myself nearing Duna but I don't really know what to do from there. Should I do what you would with Mun encounters and burn retrograde or what??

[Hotel26]

tl;dr your transfer burn (you called it the "escape burn") has to achieve a "rendez-vous", or encounter, with Duna -- or more accurately, with Duna's Sphere-Of-Influence, its (conic-patch) gravitational field.

If you set Duna as your Target and then use a maneuver node to plot the transfer burn, as your intended apoapsis nears Duna's orbit (if you're transfer window is "open"), you should see intersection markers appear on the respective orbits in the Map View.

If you can adjust this maneuver to get those to approximately coincide, you will see Duna encounter and escape indicators appear, meaning you will intersect Duna's sphere-of-influence.  If you can then actually get there, that is where and when you will perform a "capture" burn which, yes, will be retrograde relative to Duna.

                                                                                              

Just realize that the Mun's SoI punches a huge "conic patch" into Kerbin's own SOI.  It's hard to miss.

Destination Duna, you are leaving Kerbin's Soi and entering the VAST Kerbol SoI.  In which the Duna SoI punches a mere pinhead.  It is really, REALLY, a much more demanding transfer.  Just for context...  So you know what you're up against.

And how much adrenalin will jolt you when you get there.

Edited June 19, 2020 by Hotel26

[Vanamonde]

Yes, do what you would do at Mun, only more of it because Duna is bigger. Also, it has an atmosphere which will help you slow for landing. 

Meanwhile, I have moved your question from Tutorials to Gamplay, since you are seeking help rather than offering it. 

[Streetwind]

@Joe.L If you are unsure about interplanetary travel, and wish you had some way to practice it without requiring year-long missions with large, complex spacecraft...

...Well, you do! Send a spacecraft to the Mun, into a low equatorial orbit. Once there, try to go from the Mun to Minmus. This is mechanically identical to going from Kerbin to another planet, but it only takes a couple of days instead of a year. Transfer windows are much more frequent, and the stakes are lower, too. You can also do the opposite, and try to go from Minmus to the Mun.

You just have to make sure you bring enough fuel. Ideally, the spacecraft you put into orbit around the Mun should be a mostly full stage - an analogue of "I just launched this".

[king of nowhere]

actually, you can go from mun to minmus and viceversa with less than 100 m/s if you get the hohmann transfer orbit right. it's just a matter or finding the planets aligned properly.

even more difficult if you want to use a gravity assist. you can get between 200 and 300 m/s of deltaV for free if you get a gravity assist from Mun on your way out, but it will further alter your trajectory.

what i prefer to do is to launch from kerbin orbit when the alignment is about right (as seen with the intersection markers), with a gravity assist from mun, and then run a course correction manuever as soon as i'm out of kerbin's SoI because the conics look much clearer if you don't have to change system.

then once you get there you have to make a retrograde burn, just like a mun insertion. for duna you can use aerobraking to save some more fuel

Edited June 20, 2020 by king of nowhere

[Joe.L]

ok will try and put these into practice, thanks for the suggestions guys!