Is ISRU somewhat realistic?

[juvilado]

I feel like cheating when i use ISRU and was wondering...

Are Drills and Conver-o-trons minimally based on actual realistic designs or prototypes? 

[Starman4308]

Short version: do what you're comfortable with. ISRU is part of the stock game, and I have no problem with it.

 

Long version: As usual, the degree of realism in stock parts is utterly schizophrenic.

The Convert-o-Trons are far heavier than would be needed for the most frequently proposed ISRU proposals, which rely on either electrolytically cracking water/ice or possibly the Sabatier reaction to produce methane. While theoretically there are some propellants that would require tons of equipment, real-world missions simply don't have tons worth of payload capacity to spare on ISRU.

I will admit that an engineer on board might improve efficiency a bit. 25x, though, is more than a little stretching it.

Any space agency worth its salt could probably whip up a drill much lighter than 250 kg.

Thus, from a part-mass perspective, KSP ISRU is much worse than reality.

 

Having ore convert 100% to propellant is hilariously unrealistic: there will be inefficiencies.

Using fuel cells powered by converted fuel to run ISRU and drills is extremely improbable. Usually, you're taking a low-energy compound like water, and inputting energy to turn it into high-energy components such as hydrogen and oxygen. In order to see net gain from ISRU, you'd need to start with an already-high-energy compound, put in a small amount of energy to convert it to the useable fuel/oxidizer, and then break it down into low-energy exhaust products.

You typically don't get high-energy compounds existing in nature like that; over the billions of years since those planets and moons formed, they probably would have converted themselves into lower-energy compounds.

Thus, from a chemistry perspective, KSP ISRU is much better than reality.

[magnemoe]

Yes, the main unrealistic part is that you can burn the fuel and oxidizer you mine and get extra fuel.
This is impossible, as Starman4308 says, yes it work with oil and gas on earth but not on anything we will find in space, so you would need an reactor or huge solar farms for energy.

 

[Starman4308]

11 minutes ago, magnemoe said:

This is impossible, as Starman4308 says, yes it work with oil and gas on earth

I'd like to expand on this point a bit.

The reason why this works on Earth is fundamentally because of life. Life has, for billions of years, converted low-energy compounds plus sunlight into high-energy compounds.

Fossil fuels are the remains of long-dead organisms, and the oxygen in our atmosphere has accumulated from billions of years of photosynthetic organisms seeking to use the Sun's light to convert carbon dioxide and water into the high-energy organic compounds they need to grow.

I don't know of any other semi-plausible natural process that would maintain a supply of high-energy LF/O precursors on a planet without them long since having been broken down. Without an influx of energy and a process to boot low-energy compounds back into high-energy states, over billions of years, you aren't going to keep high-energy compounds around.

[tater]

@Starman4308, IMHO, the ISRU units are in fact pretty light if you are suggesting ISRU on places like the Mun. Why? Because mining regolith requires massive industrial operations since you need what is effectively a front loader to scoop regolith, then pour it into a hopper, and the tailings need to be moved as well.

The typically stock problem is that one size fits all. It's just like the lack of propellant choices that should have pros and cons. The irrationally antirealism crowd invariably complain that it's too complex, but what different props offers is pros and cons, which leads to multiple alternative mission architectures (assuming that the cons are actually modeled). The same goes for ISRU. An ISRU unit for the Mun should not work at all the way a Duna units works taking CO₂ from the atmosphere, for example. The different "biomes" (should be "geome," as none have life outside Kerbin) and the scanner should say what's in a spot, then you have to build an ISRU that works just in that kind of spot. 

[RedKraken]

A cool mod for u to look at :

https://github.com/KSP-RO/RealISRU

Lots of info about it here :

http://forum.kerbalspaceprogram.com/index.php?/topic/109771-real-isru-development-thread/&

Ive only used it under the Realism Overhaul stack.

Requires RoverDude's CRP : https://github.com/BobPalmer/CommunityResourcePack/releases

Enjoy.

 

Edited May 20, 2017 by RedKraken
RO stack

[NSEP]

No, its not. You cannot suck out fuel, like kerosene, out of rockets from another planet that has no history of life at all, unless all the Fuels are Hydrogen and Oxygen, but thats probably not true, and Monoproppelant is probably an analog of Hydrazine, wich does not form naturaly.

[Ty Tan Tu]

The ISRU is not particularity realistic and seems based on Earth type boring extraction. But I think you should not really concentrate on the widget, but think of it as a more complicated autonomous behavior. What KSP does get right is heat management. Any type of resource extraction is going to cause heat. So, for me, the engineering and management of the widget is more important than how it actually works. If you want to create a plug-in that uses the Mond process or rack, I am sure it would be greeted enthusiastically, but it is still just another abstract widget. 

As a side note...It has been brought up before, but I think it is worth repeating, distances in space should not be measured in Km or AU, but rather energetical distances. To put it in perspective, a near earth asteroid is about 50% closer in energetical distance than is the moon (That is in real life. I am not sure that is true in KSP). That is the allure of the ISRU.

5 minutes ago, NSEP said:

No, its not. You cannot suck out fuel, like kerosene, out of rockets from another planet that has no history of life at all, unless all the Fuels are Hydrogen and Oxygen, but thats probably not true, and Monoproppelant is probably an analog of Hydrazine, wich does not form naturaly.

Planetary Resources, Inc. seems to disagree with you, since they plan to do exactly that with Fe Co Ni type asteroids.

[storm6436]

Some folks might consider googling Saturn's moon, Titan.  Plenty of hydrocarbons to go around, not a lot of life. 

[Starman4308]

4 minutes ago, storm6436 said:

Some folks might consider googling Saturn's moon, Titan.  Plenty of hydrocarbons to go around, not a lot of life. 

Some folks might consider googling Saturn's moon, Titan. Not a whole lot of molecular oxygen to go around, not a lot of life.

Of course we're aware there are some places with reasonably high-energy fuels around, and maybe places with reasonably high-energy oxidizers. Not both.

[wumpus]

I think there's a mod that can make Al-based fuel out of the Mun (or Moon in RSS).  This is somewhat more realistic (I think the chemistry has been studied for a proof of concept), except you get lousy Isp.  The Isp really doesn't matter so much since you only need enough delta-v to get off the Moon, and then you simply accept that you will have a lot of mass on your ship.

1 hour ago, Starman4308 said:

Of course we're aware there are some places with reasonably high-energy fuels around, and maybe places with reasonably high-energy oxidizers. Not both.

If you can keep hydrogen in its tank (non-trivial), all you need is an oxidizer.  The low mass of hydrogen makes it an ISRU favorite (you aren't going to find an oxidizer with a similar low mass [unless hydrogen can act as an oxidizer, that wouldn't surprise me].

[Alshain]

ISRU is probably the least realistic thing in the game, as far as major features.  Fuel in general isn't very realistic but ISRU is pretty much magic.  You are basically turning rock into rocket fuel.

Edited May 20, 2017 by Alshain

[SchwinnTropius]

1 hour ago, Alshain said:

 You are basically turning rock into rocket fuel.

There really is no better way to put it than that.

[Gargamel]

2 hours ago, Alshain said:

ISRU is probably the least realistic thing in the game, as far as major features.  Fuel in general isn't very realistic but ISRU is pretty much magic.  You are basically turning rock into rocket fuel.

ISRU is not magic.  It takes a small amount of Tellerium seed material (stored in the ISRU converter) and using electrical energy, and some of the ore, creates more Tellerium.  It then is able to reverse the stable Tellerium molecule, and add it to the ore, where it also adds in a mix of Iron and Lutetium (also extracted from the ore).  From this it is able to create a stable two part mix which it can easily separate with help of a catalyst (electricity)

 

Hence: Rock + eT + Fe + Lu = Rocket Fuel. 

 

Monoprop is created with a similar method using Nitrogen, Oxygen, Molybdenum, and Praseodymium.

Edited May 20, 2017 by Gargamel

[Guest]

The ISRU in stock KSP, and, in fact, most mods about the subject, isn't even remotely realistic. One of the original conundrums I faced with RealISRU (when I was still involved) was that the most easily accessible resources were atmospheric. Extracting resources from regolith or soil is a very complicated process and requires a lot of heavy equipment.

OTOH, look closely at the chemicals found in 67P/Churyumov–Gerasimenko and you can see the potential in asteroid mining, and one of the reasons why Zubrin thought Deimos would be a gas station to the solar system.

[Alshain]

edit, NM... I'm dense tonight

Edited May 21, 2017 by Alshain

[Gargamel]

9 minutes ago, Alshain said:

@Gargamel That would be fine if you could only create mono propellant from it.

 

3 hours ago, Gargamel said:

 

Monoprop is created with a similar method using Nitrogen, Oxygen, Molybdenum, and Praseodymium.

I think you missed the satire and humor of my post.......

[Alshain]

5 minutes ago, Gargamel said:

 

I think you missed the satire and humor of my post.......

Damn, I'm usually sharper than that.  I didn't sleep well last night... thats my excuse and I'm sticking to it.  I see it now.

[Gargamel]

3 minutes ago, Alshain said:

Damn, I'm usually sharper than that.  I didn't sleep well last night... thats my excuse and I'm sticking to it.  I see it now.

All's good.  I was quite proud of that one actually.  And it came from your comment about rock into rocket....

[StahnAileron]

6 hours ago, Alshain said:

ISRU is probably the least realistic thing in the game, as far as major features.  Fuel in general isn't very realistic but ISRU is pretty much magic.  You are basically turning rock into rocket fuel.

I would argue SAS/Reaction Wheels . Those are pure magic in stock KSP . But that's beside the point.

I have yet to get myself to bother with ISRU because there isn't much to do in the stock "end-game" once you know how to consistently get into space and deal with orbital mechanics as a beginner. Maybe once/if I get around to figuring out EPL or that other off-world construction mod...

I gave up on KSP regarding "realism" long ago. (It's a game; you need to give up at some point.) As long as it's balanced for whatever gameplay the devs intend... *shrug*

[Alshain]

27 minutes ago, StahnAileron said:

I would argue SAS/Reaction Wheels . Those are pure magic in stock KSP . But that's beside the point.

I have yet to get myself to bother with ISRU because there isn't much to do in the stock "end-game" once you know how to consistently get into space and deal with orbital mechanics as a beginner. Maybe once/if I get around to figuring out EPL or that other off-world construction mod...

I gave up on KSP regarding "realism" long ago. (It's a game; you need to give up at some point.) As long as it's balanced for whatever gameplay the devs intend... *shrug*

Reaction wheels aren't total fiction though, they are just a bit overpowered, especially in the atmosphere.  ISRU is total fiction.

[KerbMav]

The problem - as usual - comes from KSP not specifying what liquid-fuel is meant to be and at the same time using it in atmospheric planes and rockets at the same time.

In reality I guess making H2 and O2 from water - which can be found almost everywhere - would be quite possible, no?

[StahnAileron]

8 hours ago, Alshain said:

Reaction wheels aren't total fiction though, they are just a bit overpowered, especially in the atmosphere.  ISRU is total fiction.

I meant in how they're implemented in KSP. Though it was a gameplay compromise I can understand. Still, infinite torque (over-time) eliminates the need for RCS rotation controls in most cases. (Massive builds still need them to turn within a reasonable timeframe.)

ISRU as implemented in KSP is fictional as well, but just like SAS/RWs, it's a gameplay compromise I'm totally fine with. At least ISRU has more things to balance it out. RWs just have output strength, EC use, and mass.

3 hours ago, KerbMav said:

The problem - as usual - comes from KSP not specifying what liquid-fuel is meant to be and at the same time using it in atmospheric planes and rockets at the same time.

In reality I guess making H2 and O2 from water - which can be found almost everywhere - would be quite possible, no?

The un-reality is the amounts you would expect to find and being able to fill a giant fuel tank. Water is a volatile in the environments of space, so it's actually hard to find in significant amounts across the board on planetary bodies. Granted, the ore concentration system sorta mimics that, but "ore" typically implies something else. Very generally speaking, you're not gonna find much water near the equator of most bodies. (Unless you have something like Earth/Kerbin/Laythe with temps and atmospheric pressure to help contain it.)

Still, gameplay mechanics. As stated by the devs before, realism takes a backseat to fun and playability. There just needs to be a bit of justifiable logical sense.

[Guest]

5 hours ago, KerbMav said:

The problem - as usual - comes from KSP not specifying what liquid-fuel is meant to be and at the same time using it in atmospheric planes and rockets at the same time.

In reality I guess making H2 and O2 from water - which can be found almost everywhere - would be quite possible, no?

KSP's fuel and oxidizer are not meant to be cryogenics but hypergolics. They are infinitely storable, are used in engines that can infinitely restart and throttle very deeply, and have the hsp of Aerozine50 and dinitrogen tetroxide. While in reality we might mine water and/or methane relatively easily for our craft in KSP you're literally reprocessing complex molecules from "dirt".

As pointed out, "realism" takes a backseat to players being able to refuel anywhere.

[lajoswinkler]

Absolutely not. It's laughable and that's one of the reasons I've removed it from my game.