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What is best way to make kerballed flight to Duna (with landing) and back


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Moving to Gameplay Questions.

As has been pointed out:  it depends on what you're aiming for.  Best at what?

However, if what you're really asking is something along the lines of "I've landed and returned from the Mun and Minmus, now I want to move on to Duna and I'm not sure what to do", here are the key takeaways:

  • Transfer window really matters.  Pick a good window, and it takes only barely more dV to go to Duna as it does to go to the Mun.  Pick a bad one, and it's much more expensive.  There are lots of transfer planners out there-- this one's my favorite.  TL;DR:  launch when Duna is about 45 degrees ahead of Kerbin.
  • Aerobrake on arrival.  Duna has an atmosphere.  Use it.  This will save you a lot of dV due to not having to do a braking burn on arrival.  A couple of things to be aware of for Duna aerobraking:
    • Altitude can be finicky.  When you're on final Duna approach, it's a good idea to quicksave your game and experiment with various Pe altitudes.
    • Duna reentry is really gentle, compared with Kerbin.  You probably don't need to bother with a heat shield.
  • Use drogue chutes.  Duna's atmosphere is really thin, and it's easy to faceplant while still going a lot faster than regular chutes can open.  Drogues really help.
  • Consider a partly-powered landing.  Duna's atmosphere is so thin that you need a lot of parachutes if you want to slow your ship down enough to land safely on parachutes alone.  Certainly that's doable, but you need so many parachutes that you pay a price in fuel lugging them across the solar system.  An alternate approach is to put just a little bit of parachutes on (say, one regular chute and a pair of drogues), which is enough to slow your descent to 20 or 30 m/s.  Then just use a brief burst of engine thrust, right before you land, to cushion the landing.  The fuel you burn for that one brief burst is a lot less mass than lugging a whole bunch of parachutes.
  • Returning to Kerbin is a lot more dV than returning from the Mun.  From the Mun's surface, it takes around 800-900 m/s of dV to go home to Kerbin.  From Duna's surface, it takes something like 1800 m/s, if you do a really efficient ascent and have a good transfer window home.  That's a pretty big gap, be sure to allow for it.  You can certainly do a direct-ascent landing, but personally, I like to do somewhat more Apollo-style:  I leave an orbiting fuel tank upon Duna arrival, so that I don't carry my go-home-to-Kerbin fuel down to the surface and back.  That does save on quite a bit of mass, but it also makes arrival rather more tricky, because aerobraking to orbit rather than going down to the surface is incredibly finicky-- a difference of half a kilometer's Pe altitude can mean the difference between "go flying off into interplanetary space" and "go down to the surface."  So, basically it comes down to a choice between either Apollo-style or direct-ascent return.  The former is leaner and more efficient, but trickier to design and fly.  The latter is simpler and easier, but significantly bulks up the mass of the mission.  Which is "better" for you depends on your priorities and your play style.
  • Don't forget Ike.  It's big, it's got a lot of science, and it's in the way.  You may want to consider beefing up your mission so you can visit both Duna and Ike.  But even if you plan on visiting only Duna... make sure that you're paying attention to your arrival path so that you don't blunder into Ike.  It's big, it has a large SoI, and it orbits quite close in to Duna, so it's very easy to have accidental/unwanted Ike encounters.  It's nothing you can't work around, just something you have to watch for.  Kind of like living on a street where one of the neighbors has a cow that's in the habit of wandering out into the street:  watch where you're driving.  :)

 

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Probably maybe an apollo style mission. Or just a simple souped-up mun lander attached to a beefier transfer stage. This is to account for the extra dV needed to get to duna and the extra dV needed to land and take off. Parachutes do work on duna though so those are probably helpful to slow your descent somewhat.

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50 minutes ago, qzgy said:

Or just a simple souped-up mun lander attached to a beefier transfer stage.

I would vote for this as the simplest.  Often called "direct ascent" around here. 

A Duna mission does not take much more delta-v than a mission to the Mun and back, once you factor in the "free" capture thanks to Duna's atmosphere.  Just add a little extra safety margin, put some parachutes on your lander, and make sure it's not horribly un-aerodynamic, and you should be good to go. 

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