A mostly successful Duna mission.

[ArmchairGravy]

I finally quit beating around the bush and decided to go for a Duna return mission. I sent a satellite to scope the terrain, an orbiter to act as the return, and a lander. Since the trip out took 1100m/s, I thought I had plenty of fuel, especially since the lander could dump its excess into the orbiter once it made its way back up.

As this is my 1st interplanetary mission, I didn't realize that 1100m/s would have to be canceled out. Whoops!

The good news is that I had enough fuel to properly orbit everything, and was able to land and then rendezvous with the orbiter. Flag planted! The bad news is that even after refueling the orbiter with the remains of the lander's supply, I don't have the juice to get back home. I'll have to send a gas tank over when the next window opens up.

So while I was able to achieve most of my goals, a flawless interplanetary return was not achieved. Now I know I have to take into account the fuel for those insertion burns, and to plan for those to take just as much fuel as the outbound burn.

[Captain Sierra]

Not necessarily. Going to Duna, you lose some of that velocity as you reach the height of your orbit (near intercept). If you take 1100m/s ejection burn, it's something like 600-700m/s to circularize. Of course, if you aerobrake between 12-14km altitude at Duna, you can capture into a nice orbit no retrograde burning required, except to circularize. That saves you like 400-500m/s dV right there.

[ArmchairGravy]

Lol. The closest periapsis on insertion was 2.5Mm. Aerobrake insertion? Ahahahahahahahahahaha. Yeah, that's gonna happen. It was struggle enough just to get ANY insertion when leaving Kerbin.

You must have better skills than I as I had to kill roughly 1100 m/s just to get an orbit. I used nodes at periapsis so this is not a guess. Getting down and circular was not even included in that figure, and frankly was a minuscule fraction of the fuel I burned.

I'll just make sure to account for those insertion burns next time I go interplanetary.

[ArmchairGravy]

OK, Captain, I'm beginning to see what you're talking about. I sent a probe to Eve, and again was way out on the initial insertion. I messed about thrusting in different directions and ended up with an aerobraking insertion. Lesson learned!

[Scotius]

You can also use aerobraking to semi-circularise the orbit. It might take couple of passes, but it saves a lot of fuel too. Just don't let periapsis drop too deep. I practised it returning my missions from Minmus - fun, but it takes more time than direct maneuver.

[mellojoe]

I find that after you push away from Kerbin, get out of the sphere of influence, you can then mess around with your trajectory and change your approach significantly with very minimal fuel. Essentially you are doing a course correction from as far away as possible. About 1/3 or 1/2 way between where you are coming from and where you are going to, you can make large changes very effeciently. If you play around with it you can start to figure out which way you need to burn to make the correct adjustments. North, East, Prograde, etc. Oftentimes, you can use tiny amouts of RCS even, and still change your approach by a significant margin.

[Dkmdlb]

Lol. The closest periapsis on insertion was 2.5Mm. Aerobrake insertion? Ahahahahahahahahahaha. Yeah, that's gonna happen. It was struggle enough just to get ANY insertion when leaving Kerbin.

Once you get an encounter, wait until you are in the Duna SOI and then instead of burning retrograde to lower your Pe into the atmosphere for aerobraking, set up a maneuver along the radial in vector until your Pe is where you want it to be. It can save you a lot of fuel. Sure, you come in a lot faster that way, generally, but that just makes for better fireworks, right?