Mun Station Tips

[HeliosPh0enix]

I am planning to make an orbital station around the Mun in my career save to serve as a refueling platform for interplanetary missions and surface base construction. I have a few questions about the best way to do this. I know a lot of these are mostly up to personal preference, but please give a gameplay-related reason for any answers you choose to give. 

1. What altitude should the orbit be (ease of ISRU runs to the surface vs. rendezvous efficiency when coming in from Kerbin vs. any other factors)?

2. Where should the ISRU unit be (i.e. on a ground facility with a ship going down to pick up refined fuel, on a lander that mines and refines on the surface before bringing fuel back up, or on the station with a lander bringing raw ore back up to be refined in orbit)?

Efficiency is important to me, but sometimes ease of gameplay trumps it, and I am the type of person who likes to overengineer things. Thank you for any responses. 

[Gargamel]

12 minutes ago, HeliosPh0enix said:

2. Where should the ISRU unit be

On the asteroid you bring into orbit around the Mun.    Far more efficient to do this than shuttle ore/fuel to and from the surface.     I've had difficulty making a Mun ISRU setup efficient enough for regular use, so I just bring a class D or E into orbit around the Mun, and shuttle the ore/fuel down to the station with a tanker.    I don't use the asteroid as the station itself, cause I've had stability and ships loading inside the asteroid issues in the past. 

Probably not the answer you wanted to hear though. 

[mystifeid]

50 minutes ago, HeliosPh0enix said:

1. What altitude should the orbit be (ease of ISRU runs to the surface vs. rendezvous efficiency when coming in from Kerbin vs. any other factors)?

Anywhere above 50km. This is the cutoff for 1000x warp around the Mun.  At 1000x warp energy use for the ISRU is free - see this thread.

50 minutes ago, HeliosPh0enix said:

2. Where should the ISRU unit be

I usually have them in  bases and stations . One in a base on wheels - it is also has two big drills - which docks with my lander. So far in this career I have two Mun stations and both have ISRU's. The lander uses a mainsail to lift four large holding tanks of ore (6000 units) along with one Rockomax 32 and four Rockomax 16 fuel tanks. If I don't quite fill up the ore tanks, the lander can make it back to dock with another station in a 700km Kerbin orbit. Making it back to any of the stations in Mun orbit is considerably easier and it doesn't take many trips before the six Rockomax 64's in any of these stations are full. Anyway, I think having ISRU's everywhere gives you more options - ie the lander can refuel at a base while loading up with ore and refuel again at stations as they convert ore.

Edited April 30, 2018 by mystifeid

[Gargamel]

1 hour ago, mystifeid said:

At 1000x warp energy use for the ISRU is free

Free for your particular ship.  I've had ships that my rounding error led to loss of power, at that warp.  It depends on what else is using electricity. 

[mystifeid]

1 hour ago, Gargamel said:

It depends on what else is using electricity.

Interesting. Even with a base that has an ISRU, two drills and various other items using electricity I gain energy.

Edited April 30, 2018 by mystifeid

[bewing]

I prefer to put my interplanetary fuel depot at minmus, rather than the Mun. Easier to land, lower dV requirements, and a better oberth dive.

That said, if the point of the station is to generate free fuel to ferry back to LKO, then the Mun has a couple big advantages. Round trip time is 2 days instead of 10 for minmus. And there are no plane changes involved going from a pure equatorial Mun orbit to a pure equatorial Kerbin orbit and back again for the robotic tanker.

 

[Snark]

7 hours ago, HeliosPh0enix said:

1. What altitude should the orbit be (ease of ISRU runs to the surface vs. rendezvous efficiency when coming in from Kerbin vs. any other factors)?

2. Where should the ISRU unit be (i.e. on a ground facility with a ship going down to pick up refined fuel, on a lander that mines and refines on the surface before bringing fuel back up, or on the station with a lander bringing raw ore back up to be refined in orbit)?

As you can see from the wealth of answers you've got here, there are many different ways to do this and different people have different preferences. 

Here's my own preferred way:

First, I like Minmus more than Mun for this purpose, mainly because its gravity is so light.  Means I don't waste a lot of dV landing and returning.  Yes, this makes navigation slightly more involved due to Minmus' inclination, but I don't find that a big deal.  Either one can work, pick the one you like best. 

As for the design:  I like to build a single ship that's a miner, and a refiner, and a surface-to-orbit tanker.  And I like to make it as big as possible.  Rationale:

• As big as possible, because I like efficiency too, and what I'm trying to optimize is "fun per hour of play time."  I don't find mining runs to be especially interesting, so I'd like to not have to do a whole bunch of them.  The bigger I make the transport ship, the fewer the number of runs I have to make.
• So... if I make the ship ginormous, that means that by far the bulk of its mass is fuel tanks and engines.  Any mining/refining equipment is just an afterthought.
• Therefore, when I give it some drills, radiators, fuel cells, and an ISRU... the mass dedicated to those is a fairly small fraction of the overall mass of the ship.  Which means the fact that it's wasteful that I'm schlepping them up and down to orbit every time doesn't matter much, because it's a small waste.
• And in return... it really simplifies my overall mining experience.  There's no surface infrastructure that sits in place, so when I land, I don't have to fuss with making a pinpoint landing next to a base.  I do my mining and refining on the surface, where I can timewarp arbitrarily fast.

So, the setup boils down to:

• A giant miner/refiner that shuttles between surface and orbit
• An orbiting fuel depot that's basically just a giant fuel tank
• Whatever ships then need to drink fuel from the orbiting depot

The depot's position doesn't matter all that much.  Around 50 km seems to be a reasonable compromise between Oberth benefit, ability to timewarp, ease of rendezvous, and comsat LOS.

...Having said all of the above... I feel compelled to mention that I also usually don't bother with this at all.    Mainly because I've found that in a career game, launch costs are not all that big for me; they're dwarfed by much bigger expenses (e.g. upgrading KSC buildings) and much bigger incomes (e.g. doing contracts).  So the amount of cash I save by mining fuel off Mun or Minmus simply isn't worth all the extra hassle to me-- simpler to just launch directly from Kerbin.  In short:  There's not a really strong economic reason to build up a Mun-mining setup.  It can be really fun as a role-playing exercise ("Look, Ma!  I'm mining the Mun!"), and I've done that a fair number of times.  But it's not really a huge economic benefit.

Where I'm much more likely to use mining is on deep-space missions instead, e.g. where I'm sending out a mission to thoroughly explore the Jool system, or something.  Being able to mine and fuel on-site makes a huge difference, because it drastically slashes the amount of dV that I have to launch with.  That's a giant game benefit, given the tyranny of the rocket equation.  It's a whole lot easier to build a thing with 3 km/s of dV that can refuel itself four times, than to build a single ship with 15 km/s of dV.

[mystifeid]

12 hours ago, Snark said:

As for the design:  I like to build a single ship that's a miner, and a refiner, and a surface-to-orbit tanker.  And I like to make it as big as possible.

Is this a viable proposition for bringing ore up from any of the big four (Tylo/Laythe/Eve/Kerbin)? Can it land on/launch from any of these places and if so can it produce more fuel once back in orbit than was consumed during launch?

[Gargamel]

19 hours ago, mystifeid said:

Interesting. Even with a base that has an ISRU, two drills and various other items using electricity I gain energy.

Without derailing this thread too much more, if You want to continue this discussion more, ping me back over in the original thread.    But once you start modding, you might add some stuff that are very power hungry. 

[Snark]

9 hours ago, mystifeid said:

Is this a viable proposition for bringing ore up from any of the big four (Tylo/Laythe/Eve/Kerbin)? Can it land on/launch from any of these places and if so can it produce more fuel once back in orbit than was consumed during launch?

Probably not... but why the dickens would you?  I mean, those are literally the worst places in the solar system to try to bring back ore or mined fuel from.  Places like that are the reason one consumes fuel, not a place to produce it.

• Exploring the Jool system?  Mine Bop and Pol-- or perhaps Vall in a pinch.
• Going to Eve?  Fuel up at Gilly.
• Kerbin?  Heck, you can launch from Kerbin with all the fuel you need, why mine anything there?  Mine Mun or Minmus if needed.

The whole point of mining is to do it from somewhere with low gravity so that you don't waste all your hard-earned fuel just climbing out of the gravity well.

^ Well, that's how it is for me when I play, anyway.    I realize that other folks have different play styles and goals; not claiming that mine's "right", or better in any way.  It's just that I'm having trouble picturing the rationale.

[mystifeid]

53 minutes ago, Snark said:

Probably not... but why the dickens would you?

Mainly because of the sorts of contracts I always decline - eg bring ore from Eve's surface and land it on Gilly. If it was possible to make a lander that could make it back to orbit around these places with a surplus of fuel, why wouldn't I want one? I find it pretty painful carting loads of fuel around. I mentioned Kerbin simply because in the past it was the quickest/easiest way to vaguely test for the others - well, maybe not for Eve.

[Snark]

Just now, mystifeid said:

Mainly because of the sorts of contracts I always decline - eg bring ore from Eve's surface and land it on Gilly.

Well, yes, those contracts are awful; they don't pay anywhere near enough to justify the expense in doing them.  Which is why one declines such contracts. 

And even if you were to accept such a contract, the last thing you'd want to do is to actually bring ore from Eve.  Just do the usual thing, i.e.  if the contract is "mine ore on Eve and have ore at Gilly", simply drop a one-way throwaway lander on Eve, have it mine however much ore is called for on Eve, and leave it sitting there.  Then switch to your other mining ship on Gilly, mine the ore, and you're done.

I suppose one might deliberately mine ore out of those super-difficult places simply because it's hard, i.e. for the challenge of it or something, and of course there's nothing wrong with doing that if that's what you enjoy.    However, if the subject is "mining ore as a routine part of a career economy" and setting up a repeatable/sustainable process to fuel operations, then, well, those really aren't the places to be.

[mystifeid]

1 minute ago, Snark said:

Just do the usual thing, i.e.  if the contract is "mine ore on Eve and have ore at Gilly", simply drop a one-way throwaway lander on Eve, have it mine however much ore is called for on Eve, and leave it sitting there.  Then switch to your other mining ship on Gilly, mine the ore, and you're done.

No way. I didn't know that. And I have mining bases on both Eve and Gilly. Thanks for the tip.

[Snark]

10 minutes ago, mystifeid said:

No way. I didn't know that. And I have mining bases on both Eve and Gilly. Thanks for the tip.

No problem.  The important thing to understand is that the game doesn't put "labels" on resource contents, the way it does with ships.  Ore is ore.  It's not "ore from Eve" or "ore from Gilly", it's just "ore".  As soon as ore is out of the ground, the game has no awareness or memory of where it came from.  So it's actually not physically possible for a game to require you to bring ore "from Eve" to some place.

And, indeed, you can tell this if you look really closely at the fine print on the contract.  Note exactly what it says.  It's something like this:

• Mine <amount> of ore from <source location>.
• Be in <target location>.
• Have <amount> of ore on your vessel.

^ Note that nowhere does it actually say you need to bring ore from the source location to the target location.  Yes, it's worded in a way that kind of encourages the reader to assume that... but it doesn't actually say it.

The really fun one is where the target location happens to be Kerbin, for example where the Mun is the source location.  In that case, all you have to do is mine the ore on the Mun, and then launch a new vessel from the VAB to the launchpad that already has N units of ore in it.  The contract completes the instant your ship hits the launchpad.