Duna landing attempt (HELP!)

[ECrierie]

So i have been attempting to land on Duna for a REALLY LONG TIME! Sooo... but have yet been able to get captured by duna's gravity (i will provide a link to a couple of pictures i posted to my Facebook of my current location) hopefully i can get some help on how to get captured by duna's orbit, and if you can help me try to make it as detail as possible so i can't potentially mess it up

Pictures: https://www.facebook.com/ECEricCrierie/posts/898650403552551

[Snark]

First things first, your job will be easier if you use a good launch window so that you arrive at Duna with a low relative velocity. There is a good tool at http://ksp.olex.biz that can help you plan this. The orbit you have pictured is going to arrive at Duna with a pretty high velocity (you can tell because your path is crossing Duna's like an X, rather than being nearly parallel). That doesn't mean that it's necessarily impossible, just that you have a lot of velocity to kill.

Get your periapsis as low as possible while you're still a long way from Duna. Coming in fast like that, either your ship has to be packing a lot of dV (many kilometers per second), or else it needs to be designed to be able to withstand a fairly brutal reentry so as to aerobrake into orbit.

What sort of ship are you using? How much dV does it have? Mass? Heatshields? Airbrakes? Additional context would be helpful.

[Climentina]

You should make the adjustment on the way there,100 more days before you reach the orbit

[celem]

Yeah, set up a node as soon as possible infront of your ship and tweak it to try and lower your Duna apoapsis, its probably the radial handles. Ideally into the upper atmosphere, 35 always used to be my number for a Duna firstpass but its been a version or so. Fold solar/comms and orient retrograde for aerobraking. Spend your dV retrograde at periapsis (or as you climb after if you need solar/comms back out). Dont start too much before the periapsis or you will be lowering it.

Duna doesnt do much aerobraking, you gotta get deep for the thick stuff but i dont recall offhand where the new cutoffs are. 35 is definitely in air, but definitely wont land you.

As soon as the orbit closes (is still elliptical) you can cut engines and make more aerobrake passes to bring yourself down close to circular, then you raise that apoapsis back out of the atmosphere and voila!.

[Capt-Coulson]

Adding to the previous comments, and generalising for the sake of being relevant: I recently launched a 2.5m diameter payload to Duna, and aerobraking at roughly 15km (plus/minus 1km) using a 2.5m heatshield captured me entirely from interplanetary speed. My vessel had a mass of approximately 50 tonnes (50,000KG). As has been mentioned, you'll need to correct for this intercept beforehand, but it's perfectly ok to fine-tune your Duna periapsis once you are inside the SOI. So long as you have an intercept with the SOI, you're laughing, so to speak.

You may even need to burn a little at periapsis if you cut it too fine, so be ready for that! And, to be quite honest, you don't need a heatshield. Duna's atmosphere is quite placid when compared to Kerbin.