Can't find any information on Minmus-based interplanetary journeys

[blorgon]

I can't find any information on how to get from the surface of Minmus to Eeloo. Are direct transfers not possible? Do I really have to jump back down into Kerbin orbit? The launch window planner calculators won't calculate a transfer between Minmus and Eeloo, and I'm kind of clueless. Do I just need to do trial and error? I can't imagine I'm the only person in the history of this game to want to try flying to Eeloo from the surface of Minmus—yet I haven't found anybody asking about it here or on Reddit or in Google searches...

[FullMetalMachinist]

10 minutes ago, blorgon said:

Are direct transfers not possible?

Technically, no. As soon as you leave Minmus SOI you'll be in Kerbin's. 

11 minutes ago, blorgon said:

Do I really have to jump back down into Kerbin orbit?

Not necessarily. Full disclaimer though, I've never tried this, and have no idea if it'll actually work.

What I would suggest is to use one of the transfer calculators that you said wouldn't work, but still put Kerbin as your starting planet. But instead of a low orbit, just put in the altitude of Minmus' orbit, and that should get you close enough. You'll probably have to be in a low orbit around Minmus and eyeball when/where to place the node, but I imagine it'll work. 

[blorgon]

Keep going.

Edited June 12, 2016 by blorgon

[Nich]

You want to drop to a highly elliptical orbit from minimus to kerbin and burn at pe to be more efficient setting your pe correctly is rather challenging

Edited March 25, 2016 by Nich

[Plusck]

It'll be hard to plan, because burning straight from Minmus' orbit is not efficient (almost as inefficient as burning straight from sun orbit), and dropping back into an elliptical orbit then burning at Pe has to be done when Minmus is aligned along Kerbin's prograde direction, and isn't something you can plan ahead with maneuver nodes (hard to see, too many orbits to click forward, too jittery at Kerbin Pe to get an accurate trajectory).

I think that's why it is rarely mentioned: sure, it makes Minmus a great place to refuel since the burn at Kerbin Pe will be minimal, but it's a nightmare to plan and you're going to have to get very lucky to have Minmus properly aligned prograde at the right launch window.

And you might have to take steps to avoid the Mun while you're at it...

[Warzouz]

There are data about Jool subsystem, there could be same graphs about Minmus.

Basically, you only need to know how much dV you need to go from escape Minmus SOI to escape Kerbin SOI. Then the graph should be the same.

 

Edited March 25, 2016 by Warzouz

[Plusck]

1 hour ago, Warzouz said:

Basically, you only need to know how much dV you need to go from escape Minmus SOI to escape Kerbin SOI. Then the graph should be the same.

This isn't true: the dv maps for launch from Kerbin require you to add the dv from low Kerbin orbit. You can't, for example, burn 950 m/s to escape Kerbin's SOI then expect to get to Duna with a 130m/s burn from there.

This is why a direct burn from Minmus will be expensive. Minmus's orbital velocity is 274 m/s. Escaping Kerbin's SOI from low minmus orbit will cost a couple of hundred m/s, so you'll maybe leave Minmus's SOI with a velocity of about 400 m/s. However, to get to Duna you need to leave Kerbin's SOI heading prograde with a velocity of about 900 m/s at SOI edge [edit: just checked, and in fact it's about 980 m/s] - so you need to add at least 600 m/s to that earlier "couple of hundred", probably ending up with an escape burn from low Minmus orbit of about 900 m/s [edit: just checked and actually you need to leave Minmus's SOI with a bit more than 730 m/s in addition to Minmus's orbital velocity, which means something like a 770 m/s burn from low orbit].

That's why it's so much more efficient to drop to a low-Kerbin Pe and burn there: starting from Minmus is already the same has having done the first 900 m/s of your burn, so after bringing your Kerbin Pe down to about 70-80 km, you only need to burn another 200 m/s or so from Kerbin to get back out to Duna.

Edited March 25, 2016 by Plusck