Need an Illudium Pu-36 Explosive Space Modulator

[Red Shirt]

I installed the Arkas planet mod. I've been there before but didn't have enough dv to get back in orbit. So, I designed and tested a craft especially for a land and return mission. Launched. Warped to transfer window and burned. The path intersected Mun's SOI. That's OK, I'll just do a course correction once free of Mun. Problem is the correction requires 3500 dv. Arrrrggggh! Stupid Mun, your blocking my view of Arkas, I'm going to have to blow it up.

Seriously, when this happens would I have been better to orbit Mun then transfer from there? Gravity assist seems beyond me.

Edited October 27, 2015 by Red Shirt

[Taki117]

Don't worry about a gravity assist and instead worry about your transfer window. I don't know anything about the Arkas planet mod, but you can save dV by launching when the planets are in the appropriate positions (Arkas should be about 45 degrees ahead of Kerbin if it's further out from the sun, or about 45 degrees behind Kerbin if it's closer to the sun). In KSP, just like real life, Gravity assists using the planets natural satellite isn't the best of options as it can cause a massive correction burn. NASA usually uses other planets and a many year long mission (it took us 10 years to land on a Comet not because we needed the technology to develop, but because that's how long it took to get there) to minimize dV requirements, in KSP we hae no such restriction so Gravity Assists aren't really all that necessary.

[mabarry3]

Don't worry about a gravity assist and instead worry about your transfer window. I don't know anything about the Arkas planet mod, but you can save dV by launching when the planets are in the appropriate positions (Arkas should be about 45 degrees ahead of Kerbin if it's further out from the sun, or about 45 degrees behind Kerbin if it's closer to the sun). In KSP, just like real life, Gravity assists using the planets natural satellite isn't the best of options as it can cause a massive correction burn. NASA usually uses other planets and a many year long mission (it took us 10 years to land on a Comet not because we needed the technology to develop, but because that's how long it took to get there) to minimize dV requirements, in KSP we hae no such restriction so Gravity Assists aren't really all that necessary.

I think he's saying not that he wants to perform a gravity assist, but more or less that he has to and wants more information on it since he can't burn during his transfer window without catching the Mun. And then curious if just launching straight from Mun rather than trying to work around a gravity assist (which is actually getting in his way) would be easier.

[Taki117]

I think he's saying not that he wants to perform a gravity assist, but more or less that he has to and wants more information on it since he can't burn during his transfer window without catching the Mun. And then curious if just launching straight from Mun rather than trying to work around a gravity assist (which is actually getting in his way) would be easier.

Ah, in that case, just launch a little early, or a little later, when the Mun isn't an issue. In either case the correction is going to be minimal. If an encounter is absolutely unavoidable you would need to adjust your orbit when inside the Mun's SoI so that when you exit your correction burn is minimized (Since the dV requirement for a correction inside the Mun's SoI is going to be cheaper than outside it. Launching from a Munar orbit is going to be infinitely more trouble than just dealing with the gravity assist.

[Red Shirt]

I never thought to adjust inside Munar SOI. I'll attempt this (hopefully tomorrow). If it turns out badly, I'll try again and burn a day earlier, I just grazed the SOI so 6 hours earlier is probably enough - famous last words before drifting forever into the void...