Northstar1989

Yeah, it would actually mainly clog the reactor's heat exchanger- which would lead to a loss of Thrust and eventually cause the reactor to overheat... Implementing it as overheating of the Thermal Rocket Nozzle would work too- just as long as something eventually goes BOOM if you run the NTR too long without cleaning... Manual cleaning (by an Engineer) probably wouldn't be very safe due to the radioactivity, though... Yeah it's very useful, and I actually already mentioned this before. Didn't you see where I talked about using heated atmospheric CO2 to clean the electrodes when you carry out Solid Oxide CO2 Electrolysis on Duna!? (reaction #3 on the list of ISRU reactions I posted before) Keep in mind that if you're going to allow CO2 to be used to clear a reactor in an NTR exhaust stream, this isn't just limited to CO2 fuel-mode alone. Any exhaust-mixture that contains CO2 will have this same effect- which means that Meth/LOX propulsion will be nearly as effective at cleaning the reactor as CO2 on its own. Basically, by adding some Oxygen into the Methane-stream, you're able to remove or prevent the soot-buildup. It's perfectly reasonable to think a REAL Nuclear Thermal Rocket might actually just operate on an extremely fuel-rich Meth/LOX stream, that would basically achieve the following net reaction: 2 CH4 + 3 O2 --> 2 CO + 4 H2O That is, it might be simpler to just partially-oxidize the carbon in the first place rather than having to constantly switch off between Methane alone and Oxygen-rich Meth/LOX... The lighter mixture of exhaust-gasses also gives you an ISP intermediate between normal Hydro/LOX and Met/LOX propulsion (but at the expense of Thrust) since the main driver of Thrust and ISP is the heat of the nuclear reactor rather than the supplementary combustion reaction... Of course, there's an argument to be made for the efficiency of the latter process- because it allows you to use Methane alone where you need higher ISP (such as when making a Mars-transfer) and Meth/LOX where you need higher Thrust (such as when making your capture-burn, as Mars' atmosphere is too thin for a pure aerocapture...) Or you could maybe even just heat the reactor up early during the aerobraking-assisted capture and allow CO2 from the Martian upper atmosphere (where there probably wouldn't be much dust) to enter into the reactor and help clean it out before beginning your capture-burn... (which you would want to start at a periapsis inside the Martian atmosphere for maximum utilization of the Oberth Effect...) Regards, Northstar - - - Updated - - - Needs a negative SootFactor (I would suggest -6) to Meth/LOX propulsion as well. The CO2 exhaust-component should be able to oxidize the Carbon the same as with CO2 along, and the H2O component should help to clear out the soot as well for the same reason hot steam is often used for industrial soot-removal in real life... Actually scratch that explanation- if the combustion reaction occurs in the exhaust-nozzle of the rocket (as this is how you do Hydro/LOX LOX-augmentation), then the OXYGEN in the propellant-stream should be able to oxidize the graphite soot-deposits quite effectively... (Heated Oxygen should be much more effective than CO2 as the reaction is exothermic, and does not even require heating to become spontaneous...) I would make that a -6 or -7 to SootFactor for Meth/LOX propulsion, but consider adding a slight additional decrease to the Thrust-production (of maybe 5-10%) beyond what the soot clogging the reactor already does as C + CH4 + 2 O2 --> 2 CO + 2 H2O is actually going to yield less Thrust and energy per mole of methane or LOX than CH4 + 2 O2 --> CO2 + 2 H2O is going to... This is due to the following Gibbs Free Energy of formation values: Graphite: 0 kJ/mol Dioxygen (O2) : 0 kJ/mol Carbon Monoxide: -137.16 kJ/mol Carbon Dioxide: -394.39 kJ/mol Steam: -228.61 kJ/mol Methane: 50.6 kJ/mol (note the sign-difference!) This means that you are going to have the following Gibbs Free Energy for each reaction (which is the energy of Reactants - Products) C + CH4 + 2 O2 --> 2 CO + 2 H2O (0 + 50.6 + 0) - (2 * -137.16 + 2 * -228.61) = 782.14 kJ released per mole of Methane CH4 + 2 O2 --> CO2 + 2 H2O (50.6 + O) - (-394.39 + 2 * -228.61) = 902.21 kJ released per mole of Methane So, your energy-production is going to be 13% less, and distributed over 4 moles of gas instead of three- making for a substantially colder exhaust-stream... However your exhaust-mass is actually a tiny bit higher, which is going to increase Thrust/MW a bit at the expense of ISP... So, a 5-10% decrease in Thrust (and a 10-15% decrease in ISP) when using Meth/LOX to clean out a Nuclear Thermal Rocket seems reasonable... That's actually a smaller percentage-penalty than should apply to using Carbon Dioxide alone to clean out a reactor, as the reaction CO2 + C --> 2 CO is actually endothermic- the math for which I will try to do at a later point... Note that the Gibbs Free Energy of formation of H2 is, like Graphite, also zero, so Methane Pyrolysis (CH4 --> C + 2 H2) actually *RELEASES* 50.6 kJ of energy per mole (16.04 grams) of Methane consumed... This actually makes Methane Pyrolysis a substantial heat-source: you get 50.6 MW of ThermalPower if you consume 16.04 kg of Methane (37687 units at the density of 425.61 kg/m3 currently in the CRP 2.0 document) each second I hope that also answers your question of how much energy it takes to pyrolyze Methane with a (already hot) nuclear reactor available- theoretically, none (as the reactor's standby-heat should provide enough heat to get the exothermic reaction started, and after that with enough insulation it's self-sustaining and actually capable of heating itself up to even higher temperatures...) In fact, the main issue becomes if you have enough radiator-mass to dissipate the extra WasteHeat that pyrolyzing Methane is going to generate, not if you have enough energy to carry out the reaction... For the record, the Sabatier Reaction is also exothermic- and shouldn't require you to ramp up your nuclear reactor beyond standby-levels either (an issue I originally took up with Fractal_UK, but he didn't want to fix for balance-reasons...) CO2 + 4 H2 --> CH4 + 2 H2O (-394.39 + 0) - (50.6 + 2 * -228.61) = 12.23 kJ of energy RELEASED per mole of CO2 (or for every 4 moles of H2) Note that the Sabatier Reaction is considerably less exothermic than Methane-Pyrolysis, and thus at practical levels of insulation is still going to require some external-heating to proceed- but MUCH less energy than Fractal_UK has currently coded the Sabatier Reaction to consume... Regards, Northstar

Another great idea! I heartily agree/approve of that idea, even if I don't really have to coding expertise to be of much help with it... You converted excess Methane- don't you mean Ammonia? Unless you already added one Methane Pyrolysis without announcing it there is currently no way to convert Methane into Hydrogen... Regards, Northstar

What do you mean by "based on the context". The code you actually posted doesn't have any glaring faults I can spot, but it is important that it be applied in the correct place- as that is the code that either scales the power output of the Molten Salt or Gas Core Reactors (I can't tell from "MSRGC" which exactly it is- they used to be one part but now FreeThinker made MSR and GC two separate parts- and I don't know which he left with the original name- which could probably use some cleaning up to be either "MSR" or "GC" not "MSRGC" at this point...) or the power-consumption of the Cryostats- both of which are critically important parts in KSP-Interstellar Extended. Looks like I'm going to have to go and load up the game and double-check that both parts are scaling correctly with TweakScale... That's a great idea- and one I was already toying with before! FreeThinker, we should probably add this to our to-do list while we're playing around with ISRU at the moment... (this is not something I would know how to code, unlike perhaps the ISRU reactions themselves- so it's definitely something you'll have to come up with a solution for...) Regards, Northstar

That seems about right. Methane decays into graphite (which will clog up engines if you're not careful) and Hydrogen when it pyrolyzes. Same effective increase to thrust, but then you have to do something about the graphite build-up... (I guess if you managed to get it suspended in the exhaust stream you would actually have a slightly larger thrust-multiplier than Ammonia- as gas volume doubles AND you get these little dust particles of Methane suspended in it AND both exhaust components will start promptly burning with Kerbin's atmosphere as soon as they are exposed to atmosphere when leaving the rocket-nozzle, for a free afterburning-effect on Kerbin...) CO2 doesn't decay into much of anything at the relevant temperatures. Breaking it down into graphite and Oxygen, or Carbon Monoxide and Oxygen, is going to require an electric current and catalysts (it doesn't become spontaneous at any reasonable temperature), and is a fairly power-hungry process.... Regards, Northstar - - - Updated - - - O:o - I wasn't aware of that. We've still got the other 7 ISRU reactions to think about, though! Regards, Northstar

My next launch was of the Control Module for the Munar-1 tug... This component contains the probe core (a MechJeb2 radial unit- mainly for the enhanced telemetry and Delta-V budget calculations- though the extra precision in executing maneuvers is also nice...) another large fuel tank (this segment containing both Ammonia and Hydrogen tanks...) and a reaction wheel... As usual, the launch-stage was recovered after the launch: The central engine (the launch-stage is propelled by a 7-engine cluster with a single engine in the center it uses for landing) cut out for no discernible reason just seconds from spalsh-down, though... (not pictured as I quickly switched back to the Main Mission before buggy water-physics could destroy any part of my launch-stage...) Luckily the launch-stage didn't have enough time to pick back up dangerous levels of velocity before it splashed down. I'm still not sure why the engine cut out, as it hand plenty of fuel left, though... The Control Module then proceeded to rendezvous and dock with the Fuel Module- which proved to be a rather annoying/difficult docking as the Fuel Module had no attitude-control capabilities whatsoever... And then, with only scant scraps of electrical power remaining, the upper stage decoupled and recovered to the near vicinity of the KSC... Only AFTER I acidentally decoupled the Control Module from the Fuel Module and had to kick myself and quickly dock them again... All in all, it was a slightly bumpy, but largely successful mission... By the way, take note of the fact that the Munar-1 tanker has tanks for both Nitrogen and Hydrogen, as well as Ammonia (which is composed of Nitrogen and Hydrogen). Although I won't be using it in this capacity just yet, this DOES allow me to eventually use the tug for hauling Ammonia manufactured from ISRU around (for instance from Nitrogen scooped off Kerbin or Laythe with a Propulsive Fluid Accumulator, and Hydrogen from Jool or launched from the surface of Kerbin) or to hold Nitrogen and Hydrogen from breaking Ammonia back down via electrolysis (Ammonia is basically the densest possible way to store Hydrogen- holding more than twice as much hydrogen-mass per cubic-meter as actual Liquid Hydrogen, and having an even higher hydrogen-fraction than Water such as to beat it out for hydrogen-storage density despite Ammonia's comparatively lower overall density... Also, unlike Liquid Hydrogen, Ammonia will never boil-off in RealFuels or real life...) Both these functions courtesy of KSP-Interstellar Extended and the KSP-I ISRU Refineries in it. These storage-capacities, as well as the overall high ISP of the Particle Bed Reactor-based Nuclear Thermal propulsion system (which won't soon become outdated, unlike chemical rockets, which increase in tech-level and thus slightly in ISP and Thrust with every new rocketry node I unlock in RealFuels...) mean that this tug will likely see extended re-use well into the future after I am done with the Munar-1 mission... Regards, Northstar

Actually, that's *exactly* the kind of thing I meant by mid-mission refueling allowing use of ISRU. Cool demonstration of the concept though- rock on! Regards, Northstar - - - Updated - - - Actually if you're taking your refueling rig along with you like that, smaller rigs are more efficient despite having to make more trips- because they require less fuel to get out to the planet/moon in the first place. In the long run, larger rigs are more efficient because they have relatively less mass in probe cores, landing legs, batteries, etc. and more in fuel-tanks: but for a mobile operation like that smaller rigs are much more efficient... Also, Karbonite was undepletable last I checked. Did they change that recently? Because honestly, having depletable resources makes zero sense- the scale you are going to be extracting resources on is going to be *miniscule* compared to the mineral reserves or atmosphere or whatnot of even a local resource deposit on a planet/moon... It would be like going to an oil field on Earth and having it run out after just a couple days for resources to deplete on the tiny scale of a space program... EDIT: Nope, they didn't change that. It still says right in the release thread's OP: "Karbonite's resources are inexhaustible. Kethane's resource deposits can be depleted." So, either you're mixing up Karbonite and Kethane, or there's something wrong with your version of Karbonite, if your resources are being depleted... It pays off to set up permanent outposts though. This doesn't even have to mean an actual depot in orbit or a refinery on the surface or in orbit. Simply sending an extractor-lander like the one you just showed to each planet and leaving it for the next mission (and the one after that, and the one after that...) will save you fuel if you carry out enough missions... But I'm sure you're aware of that! Regards, Northstar

Oh cool, you're adding ISRU reactions already! I thought you were going to wait for me to figure out how to draw up some code for them! In that case, here are a list of reactions we should strongly consider including- I can provide more details and chemical formula (or, eventually, code- once I figure out how to create it for the KSP ISRU system...) for any/all you're willing to add: (1) Sabatier Reaction run with onboard resources only- so players can run orbital refineries around Duna with Carbon Dioxide collected by Propulsive Fluid Accumulators and Hydrogen shipped from much more infrequent launches from surface water-mining outposts on Duna (this is MUCH faster and more efficient than having to produce all your Methane and LOX on the surface and THEN launch it to orbit, as you don't have to accelerate any of your Carbon or Oxygen to orbit if you scoop it from the edge of the atmosphere while already in orbit...) (2) The Reverse Water Gas Shift Reaction. Converts Carbon Dioxide into Carbon Monoxide and Water. The water can then be electrolyzed to recover the Hydrogen- allowing you to run this reaction ad-infinitum to isolate Oxygen from Carbon Dioxide scooped from Duna's atmosphere with a Propulsive Fluid Accumulator... The Carbon Monoxide could either be thrown away (hey, it's no loss if you basically have an unlimited source of Carbon Dioxide readily available) or stored for the Fischer-Tropsch Process... (3) Direct Carbon Dioxide Electrolysis (also known as Solid Oxide CO2 Electrolysis, or SOCE in typical NASA-lingo...) Converts Carbon Dioxide into solid carbon (graphite) and Oxygen. Doesn't work so well in space (such as with Carbon Dioxide form a Propulsive Fluid Accumulator) as the graphite tends to gook up the reactor, but provides a great (and faster and more energy-efficient) way to isolate Oxygen directly from any atmosphere containing Carbon Dioxide. The suggested way of clearing out the graphite (and what would be done by NASA in the designs they've considered) is to blast the equipment with more hot Carbon Dioxide regularly- which will convert the graphite and some of the Carbon Dioxide into Carbon Monoxide (the requirement for this cleaning-process means that this reaction should really only work inside the atmosphere, though... Not necessarily on the ground- it would also work with a plane flying at high altitude or a high-powered rocket "flying" well inside the upper atmosphere...) (4) Fischer-Tropsch Process: converts Carbon Monoxide and Hydrogen into Kerosene and Water. Very useful on Duna with RealFuels, *if* we add a Carbon Monoxide resource. Enough said... (5) Methane Pyrolysis: got excess methane? Want to get your Hydrogen back? No problem! Just stick it inside this handy insulated heating-chamber, heat it up to a good few hundred degrees in the absence of Oxygen, wait a while, and voila! You will have graphite and usable Hydrogen-gas. You have to dispose of the Methane, but this really shouldn't be too much of a problem when it's in a big solid chunk (and there are no catalysts or electrodes you have to worry about it fouling up) inside a sealed tank like this... (6) The REAL Anthraquinone Process. OK, there is already a reaction with this name in KSP-Interstellar, but it doesn't have the correct chemistry for the name... The ACTUAL process works by combining Hydrogen and Oxygen gas directly, rather than by combining Oxygen and water. An important distinction when you're somewhere like Duna orbit where you (should) have unlimited access to Oxygen via Propulsive Fluid Accumulators, but very limited access to Hydrogen, and want to make a bunch of Hydrogen Peroxide for your RCS system... We can keep the old process if you want, we just need to give it a different (more appropriate) name. (7) It's called Hydrazine, not Monopropellant. OK, this one is pretty self-explanatory, but if you're using RealFuels and combining Hydrogen Peroxide (see above) and Ammonia to make Monopropellant, it should produce "Hydrazine", not "Monopropellant". Having an actual tank full of Hydrazine is also important for the reactions below... (8) Need hypergolics? We've got you covered! There are actually 3 different hypergolic fuels (MMH, UDMH, and Aerozine) in RealFuels, but I'm just going to lump them all under the same entry here for brevity, as well as the production of their shared oxidizer (NTO- i.e. N2O4). One of the fuels (Aerozine) is actually just a 50/50 blend of the other two (and can be easily produced as such with the right conversion-reaction in-game) and is only its own resource as the other two are easy to blend, but impossible to separate back apart again once mixed... MMH and UDMH, meanwhile, are just Hydrazine with either one or two methyl-groups tacked on, respectively. So if you have a source of Methane available (Sabatier Reaction anyone?), Hydrazine (see above), and an ISRU refinery- then you can just combine the Methane and Hydrazine to get MMH or UDMH and a volume of Hydrogen as by-product equal to half the volume of Methane you put in... Really not that complicated as far as ISRU reactions go. Neither is NTO (properly, N2O4- "NTO" is just common shorthand for it, the same way HTP is for high-purity Hydrogen Peroxide...) To get NTO all you have to do is combine one part Nitrogen gas and two parts Oxygen gas together (there are some catalysts and co-catalysts involved, but we don't really need to care about them, as they are not consumed by the reaction...) VOILA! You have an unlimited quantity of highly-dense fuels that will never boil-off and will spontaneously ignite when mixed with NTO- perfect for your offworld refueling bases! Just don't let Jeb anywhere near the fuel-tanks or he might try to mix the two just to see a large explosion... Ummm, I think these are enough reactions for now. Even *MY* brain hurts from this much chemistry and research in such a short period of time... I'd love to know if you''re willing to work with me to get these resources added to KSP-Interstellar, FreeThinker. Figuring out creative and efficient ways to utilize the environment to your best advantage is half the fun of ISRU! (It's a bit like legos- you have this reaction that does this, and that reaction that does that- but how do you select the right reactions and design your mission-plan to get the propellant you want as efficiently as possible? For instance, do you set up a surface-base on the ground, or use Propulsive Fluid Accumulators from orbit?) Regards, Northstar - - - Updated - - - Ummm, I already addressed this before just today. See my comments above. The Urea is dissolved in water (in fact, that's what the "(aq)" stands for below...) You just end up combining the excess Carbon with some of the Oxygen that is produced from breaking down a bit of that water in the process... (make sure to see the paper I linked to there and HERE) To be precise, this is what the net reaction looks like: CO(NH2)2 (aq) + H2O --> N2 + 3 H2 + CO2 The water is broken down indirectly, though reaction of the urea with hydroxide ions (OH-), which naturally form in water. I'm not going to get into a complex discussion of pH and why this is exactly, only needless to say that it happens and the sub-reaction looks like this: CO(NH2)2 (aq) + 6 OH- --> N2 + 5 H2O + CO2 Read the paper I linked for more details- the precise balance of electron-transfer and such, for instance... Here's that link one more time: http://www.suttonfruit.com/pics/urea_electrolysis.pdf I'm kind of getting sick of repeating this, because I had to explain the exact same thing earlier today, as well as to players several weeks ago in the development of KSP-I Extended, the last time I mentioned urea-electrolysis, as well as on the TAC Life Support Thread where I suggested urea-electrolysis, and I think also on the Regolith thread as well IIRC (don't ask me why I mentioned it there). So please make sure to read the link I posted, and educate your fellow players about the relevant chemistry if they have any questions about it as well, so I don't have to keep repeating myself... Regards, Northstar

Actually, they can. Remember Carbon Dioxide is a resource (and there's plenty of extra Oxygen in the water the urea is dissolved in to add an extra Oxygen to the CO- some water will get electrolyzed with the water too...) Additionally, one more resource I would like to add is Carbon Monoxide, which has two major uses: (1) It can be burned with Oxygen in a CO/O2 chemical rocket, allowing much simpler/easier ISRU than the Sabatier Process (which requires Hydrogen) or water-ice mining (water-ice is only found in certain locations on Mars/Duna...) It's most useful for small exploration-hoppers that make suborbital leaps, like has been proposed in real life. (2) It can be combined with Hydrogen to manufacture Kerosene via the Fischer-Tropsch Process So, there is already one useful resource (Carbon Dioxide) that can be produced, and another (Carbon Monoxide) that could alternatively be produced (in real life which is produced would vary based on the voltages, temperature, catalysts used, etc...) that I would like to add as well. So everything you get from electrolyzing urea is actually useful... - - - Updated - - - I'm not sure I fully understand this. Could you explain it in a bit more detail? Then again, I'm tired and need a nap- so maybe that's also a factor... Urea-electrolysis is useful mainly because urea is the main component of urine. I.e. it has synergy with any life-support system. The idea was that if players have TAC Life Support installed they could use this to turn their Kerbals' waste into usable propellants... Normally, you're going to get a combination of N2, H2, and CO3- which will normally spontaneously decay and give rise to CO2 gas, a process that can be accelerated with catalysts, heating etc... http://www.rsc.org/chemistryworld/News/2009/July/02070902.asp Methinks the modder doth like his thermal rockets too much. Nitrogen and Carbon Dioxide both have quite high ISP's compared to any chemical rocket when you put them through an electric thruster. And with an electric thruster, you're probably going to want to use heavier, lower ISP propellants like these for the extra Thrust they provide anyways, as electric thrusters aren't exactly known for their amazing Thrust/MW... If you're already in orbit, electric thrusters are king because of their incredible ISP. And if you're using an electric thruster, you're going to want to use the denser/heavier propellants anyways for the extra Thrust/MW they provide... (it may come at the expense of ISP- but your ISP is still going to blow any chemical or thermal alternative out of the water anyways- and it's worth it for actually getting usable thrust-levels with your electric thrusters...) Speaking of electric thrusters... Are you looking into the ISP-display bug and fuel-flow bugs for them? I can't exactly send my spacecraft hurtling (or crawling) across the solar system with electric thrusters when they show up as having 0 seconds ISP in the VAB/SPH (making mission-planning impossible) and then say they don't access to any propellant even when the plasma thruster is sitting *right on top of* a big old LqdNitrogen tank... Regards, Northstar

No idea. Probably not much. But you're planning on carrying out the reaction in a KSP-Interstellar ISRU Refinery, aren't you? And THAT thing can operate into the multi-MW range, I think up to at least 100 MW of power for the 3.75 meter refinery IIRC (or was that for the 2.5 meter refinery?) Anyways, much faster than anything a series of converters based off Apollo-era technology (which is what the Universal Storage converters represent) could handle... We should probably try and avoid needlessly pulling in refinery/converter parts from other mods anyways, when we can just as easily add more ISRU reactions to the existing KSP-I Refinery... Regards, Northstar - - - Updated - - - There are loads and loads of ISRU reactions I've been wanting to add (including urea-electrolysis for when TAC Life Support is installed- allowing you to recycle WasteWater into drinkable Water and obtain usable Nitrogen and Hydrogen for propulsion from it simultaneously...) for some time now- so I'm glad you're finally looking at ISRU! However, I don't know how to access or work with the ORS ISRU code. Or even for sure where to find it. As I understand it, it is buried within the WarpPlugin .dll file? I don't currently have any software that can open .dll files, and I only have about 800 MB of usable disk-space available on my laptop (I know, yikes!) Can you recommend any small, *efficient* (don't take up a lot of space), easy-to-use programs to open the .dll file up to get at the ISRU code? EDIT: Also, I was also looking at adding some of the resource-to-resource conversions that don't involve an environmental component (i.e. like the Haber or Sabatier processes- which can draw their Nitrogen or CO2 from an atmosphere instead of from internal resources) using Regolith code, since it might be simpler and easier to work with when no atmospheric intake is involved (for those cases I do believe ORS still has the advantage). How do you feel about this? It would require re-distributing Regolith as a dependency, which worries me because if Regolith ever stops updating it could leave us high+dry... (say when 1.0 is released and a lot of the Regolith code becomes part of the stock resource-system) But on the other hand the ease-of-use for the converter code means we could probably whip up more useful ISRU reactions, faster... Also- would there be a way to make Regolith-based ISRU reactions show up in the existing ISRU menu that Fractal_UK put so much sweat, blood, and tears into creating right before he had to go AWOL? (and didn't get a chance to actually USE it to add more ISRU reactions as planned...) I really don't want to make players have to search through two separate menus- one for ORS based reactions and one for Regolith-based reactions, in order to find the ISRU reaction they are looking for... Regards, Northstar

That number seems... Over-optimistic to say the least. No electrolytic process can consume less than the Gibbs Free Energy of formation of the compound, and the Gibbs Free Energy of Ammonia formation is -16.4 kJ/mol. Which means it should cost approximately 16.4 kJ/mol * 1 kW-s/kJ * .001 MW/kW * 1000 g/kg * (1/17.031 g/mol for ammonia's molar-mass) * (1 / 0.1776 for the 17.76% hydrogen-fraction of ammonia) = 42.95 MW/kg of hydrogen-formation, not 7.4 MW/kg... That source comes up with an overly-optimistic estimate of power-consumption partially by using a Gibbs Free Energy of formation of -10.984 kJ/mol instead of -14.2 kJ/mol, which conflicts directly with the value from Wikipedia (which it says ultimately come from Lange's Handbook of Chemistry (1999)). So, either the value used in that source is wrong, or the value on Wikipedia is wrong- both can't be true... However even using a Gibbs Free Energy of -10.984 kJ/mol, the power-consumption should still be around 10.984 kJ/mol * 1 kW-s/kJ * .001 MW/kW * 1000 g/kg * (1/ 17.031 g/mol for ammonia's molar-mass) * (1 / 0.1776 for the 17.76% hydrogen-fraction of ammonia) = 33.23 MW/kg of hydrogen produced, not 7.4 MW/kg... So I'm really not sure where that number comes from... OK, well there is an alternative explanation for the difference in Gibbs Free Energy, at least- http://www.rsc.org/suppdata/cc/c0/c0cc01982h/c0cc01982h.pdf'>the source you cited assumes the reaction occurs at 25 degrees Celsisus and very low vapor pressure. The source used by Wikipedia appears to assume the reaction occurs at 0 degrees Celsius and 1 atm of partial pressure for each electrolysis product. Of the two, the latter (reaction at 0 degrees Celsius) would be closer to the actual conditions likely to be found inside the ISRU refinery- after all this reaction is occurring in the depths of space, and even reaching 0 degrees Celsius (to increase the reaction-rate) would require active-heating of the reactor! The decomposition of Ammonia becomes drastically less energy-costly the higher the temperature: in fact it even becomes energetically favorable at the temperatures of a Nuclear Thermal Rocket! (which leads to spontaneous decomposition of the Ammonia and generation of additional Thrust...) That value for energy-consumption of water electroylsis is also inaccurate. It's also too low (Wikipedia states that it requires 11.7 MW per cubic-meter of Hydrogen produced with an 100% efficient electrolysis- and the Hydrogen has a density of 0.085 kg/m3 at 1 barr and 15 C - meaning 137.65 MW of power should be required per kg of Hydrogen produced... And keep in mind that this assumes high-temperature electrolysis and low partial pressure of Hydrogen, neither of which are likely to be the case for a space-based ISRU refinery...) And you don't cite your source for it. Please provide a source so I can see why the value is so low... The rate the electrolysis occurs at is directly-proportional to the power-consumption. So there is no such thing as the "rate being too low" to feed an engine- if you crank up the power high enough you can feed *any* engine with hydrogen from ammonia-electrolysis (and conveniently, KSP-Interstellar automatically uses all available surplus-power to run ISRU reactions as quickly as possible- up to the maximum power-consumption the ISRU refinery can handle...) Of course, that's not really a concern of any relevance here- because we're not assuming running an engine directly off the electrolysis products. Instead we're talking about converting LqdAmmonia into LqdHydrogen/LiquidFuel (depending on if the player has RealFuels installed) and LqdNitrogen. The electrolysis process can be carried out over weeks, months, or even years prior to the propellants actually being needed in an engine- so electrolysis rate is not really a concern... Also, you're correct that the energy needed to cool the electrolysis-products back down to their cryogenic temperatures needs to be accounted for (which would increase power-requirements further). But the power-requirements to do that are really going to depend a lot on the energy-efficiency of the cooling systems, so I'm not even sure where to begin with that, or what would constitute a reasonable energy-efficiency for a space-grade heat exchanger... Regards, Northstar

Re-posted from a PM for future easy reference: Regarding the energy-requirements, all you need to do is look at the magnitude of the Gibbs Free Energy of formation of Water vs. Ammonia... Water: -237 kJ/mol Ammonia: -16.4 kJ/mol Note that this is the Gibbs Free Energy for pure ammonia- it requires more energy to electrolyze (26.57 kJ/mol) if it's dissolved in water... (dissolving ammonia in water releases energy- separating the two again consumes it...) 1 MW = 1000 kJ/s, so this means that it requires a minimum of 0.0164 MW per mole of Ammonia you need to electrolyze. As a mole of Ammonia weighs 17.031 grams, this means it requires a minimum of 9629.5 MW to electrolyze one metric-ton of Ammonia (1424298.5 units of Ammonia in KSP using a density of 702.1 kg/m3, or approximately 147.91 units/MW, or approximately 0.006761 MW/unit). These are also numbers assuming a 100%-efficient process, so you can round them up to reflect inefficiency and get nice even numbers to your heart's content...

Don't worry- there won't be any more discussion of those proposed resources, I already extended an invitation to Nertea and NathanKell/Regex/Starwaster to join in using those resources- which is the main reason I mentioned them here... Why would the resource-list be locked at this point though? If KSP-I Extended can push through some new resources (and delete a couple existing ones that only it uses) and make sure the changes are good-to-go before the deadline, without any input/help from any other modders, then why would it be an issue pushing to get these resources added before the CRP 2.0 development deadline later this week? Regards, Northstar

Way ahead of you Sal I assume you meant the discussion of LOX-density, of course? (since that was what RoverDude wanted me to stop discussing) The mention of adding supercritical-fluid noble gasses is something that I just brought up, and has never been discussed before (at least not recently) and is an entirely separate topic- one that I quite reasonably have the right to comment on in this thread, especially given that I help maintain/develop one of the mods participating in this effort (KSP-I Extended) and am trying to recruit other mod-authors to use these resources in their mods as well... Of course, it was just a comment- not a discussion. There's no need to follow up on that unless Nertea or NathanKell/Regex bite on wanting to collaborate on these resources. Otherwise, adding supercritical noble gasses is just a private matter between myself and FreeThinker. Regards, Northstar - - - Updated - - - Wait, FERRAM (the creator of the LEGENDARY Ferram Aerospace Research mod) asked for weird solid fuels? What did he want added, exactly? Regards, Northstar

It was a disappointment. But it did give me an excuse to re-design my mission to be more efficient... Anyways, the first thing I did after that disaster was to complete a contract to launch a Kerbosynchronous satellite to make a bit of money... That went smoothly, Space-X style as is usual for my launches (although I didn't quite have enough fuel to make it back to the launchpad with the launch-stage...) Regards, Northstar - - - Updated - - - OK, so I decided to carry out my Munar-1 mission differently this time. The first launch was of a fuel-module... This payload consists of a large fuel tank containing LqdHydrogen (which will be used by a Nuclear Thermal Tug transfer-stage) and some hypergolics for the Lander... Following that, I launched the engine-module. I rarely use the same rocket twice, but for the sake of time I decided to just re-use the same launch vehicle as before with a few minor refinements... (re-using launch vehicle designs is more realistic anyways) I called it a "tug" (like I called the fuel-module a "tanker") but it is really just a big liquid Hydrogen tank with a nuclear thermal rocket engine attached. It has no command or control ability of its own, and will rely on other mission-modules for that... The pictures cut out kind of abruptly (as that's where I took my last screenshot), but what I basically did was park the engine-module extremely close to the fuel-module, leaving it attached to its upper-stage so I could keep the Hydrogen tanks in the payload topped-off at the expense of reserve-fuel from the upper-stage being used to replace boil-off... I'll use another module to dock the fuel and engine modules together later... Regards, Northstar P.S. Despite recently drawing up a more reasonable set of tech-limits for ProceduralParts that allowed me to utilize 3.75 meter engines for the Launch Vehicles instead of being limited to 2.5 meter parts (as the fuel tanks are now limited to 4 meters at the tech-level when NovaPunch2 gives players their first 3.75 meter engines, not 3 meters...) and using them in this save while I wait for them to (hopefully) officially become a part of ProceduralParts (the current tech-limits were so ancient that fuel tanks limits were based off the tech tree before the SLS parts were even introduced...) I still have to conduct this mission with multiple launches. I simply can't lift heavy enough payloads with 4 meter diameter rockets to put 5 Kerbals on the Mun in just one launch (Saturn V was 10 meters in diameter in real life!)

Not the density of LOX at its boiling-point. That's less than 200 kg/m3, as I pointed out before. 1142 kg/m3 is the density at the significantly lower temperatures and slightly higher pressures (the latter only important for phase-transition and the temperature at which you find the boiling-point), such as were used on the Shuttle External Fuel Tank and the Saturn V LOX tanks... You may have been misled into thinking the temperature of the LOX used was at the boiling-point because 99% of sources of the Shuttle EFT and Saturn V LOX tanks use hand-waving statements like "The liquid oxygen tank functions as a huge vacuum bottle designed to store the cryogenic fluid at a very low temperature -- less than minus 297 degrees Fahrenheit" (this is from an article on NASA.gov). This leads people to incorrectly thing the LOX was stored at -297 F (which is the boiling-point of LOX), when the key phrase here is actually "less than". The actual storage temperature on the pad must have been around -320 F, based on what we know of the LOX density in the Shuttle EFT. As the Shuttle ascended, this temperature could have been allowed to climb- as the LOX storage would not need to be as dense as the LOX tanks progressively emptied their mass into the engines- but it would always have to remain below -297 F in order to keep the LOX as a liquid: hence the phrase "less than minus 297 degrees Farenheit". OK, well anyways, this is a dead-end discussion. So I'm going to drop it here... On to other topics... Regards, Northstar - - - Updated - - - OTHER TOPICS: OK, so in real life (or at least on the Deep Space One and Dawn probes) the noble gasses used to propel ion engines (which have heretofore used Xenon due to its superior thrust and density- but could use lighter gases like Argon for better Exhaust Velocity and thus ISP if more electrical power was available, as with an onboard nuclear reactor...) are stored as supercritical fluids, not as gasses. Here are the densities/temperatures/pressures of the different useful (helium is too expensive and difficult to store) noble gasses as superciritical fluids: Neon: 481.91 kg/m3 - 26.79 atm, -228.66 C Argon: 535.6 kg/m3 - 48.63 atm, -122.46 C Krypton: 909.21 kg/m3 - 55.25 atm, -63.67 C Xenon:: 1102.9 kg/m3 - 58.42 atm, 16.59 C KSP-Interstellar Extended already has a NeonGas and KryptonGas entry on the CRP document, and I has suggested to FreeThinker we delete these and replace them with "SuperCrit Neon" and "Supercrit Krypton" instead. I also suggested KSP-I Extended add its own "SuperCrit Xenon" and "SuperCrit Argon" resources so as to not interfere with the existing "ArgonGas" and "XenonGas" resource definitions... I mention this here because I was wondering if: (1) NathanKell, Regex, etc. would be interested in adding supercritical noble gasses as resources with native RealFuels support. Basically, just add tanks definitions for these resources to RealFuels that rely on the definitions used in the CRP 2.0 release we are currently working on... (2) Nerta would be interested in jumping on this bandwagon, and swapping NearFuture Propulsion to use a "SuperCrit Argon" resource instead of "ArgonGas" for its electric thrusters... The benefits of using superciritcal noble gasses instead of their gas phases at STP should be quite obvious: (1) You get much better mass-fractions than with gaseous storage. For instance, Argon is 300.9 times denser as a supercritical fluid (535.6 kg/m3) than as a gas at STP (1.78 kg/m3). Argon is only pressurized to 48.63 barr at its critical point, meaning you're going to require about 50 times the tank mass (the minimum tank-mass is directly proportional to internal pressure for a pressure-vessel in vacuum) for about 300 times the fuel mass. Which isn't a bad deal really- even if you chill ArgonGas to just above its boiling-point (-186 C) you're only going to increase fuel-density 3.24-fold (based on a density of 5.772 kg/m3 for Argon at -185 C). A better fuel tank mass-fraction means lower propellant-requirements for the same Delta-V or more Delta-V for the same fuel mass: which amounts to major cost-savings when you're sending a probe all the way to Eeloo... (2) Your much higher fuel-density means your ion probe (or even nuclear-electric manned spacecraft!) has a much smaller aerodynamic profile. It's the difference between trying to lift a crumpled up ball of paper and a ball of lead through the atmosphere- and your Delta-V costs are going to be much, much lower (several hundred m/s lower if your launch vehicle only carries your probe to Low Orbit) to get the same mass of supercritical fluid to orbit considering the incredibly low density of the gas-phase... With the new drag-model in the stock aerodynamcis system coming out in 1.0, things like fuel-density will actually affect Delta-V costs to orbit without having to install FAR, and you will also be able to get away with a smaller probe inside cheaper+smaller fairings if you are using supercritical propellant on your interplanetary probe... Regards, Northstar

Alright, will do. I'll make sure FreeThinker knows he has full permission to change the density. Also, who's responsible for ratifying the LqdCO2 resource? It's used by KSP-Interstellar Extended (and no other mod that I know of, now that BioMass was removed from the process due to lack of communication), but is currently listed as a USI resource. Why is this? As it stands, I see no issue with the density, cost, or any other parameters of LqdCO2- so I would very much like to see it ratified. If it was listed as a KSP-I resource, I could ask FreeThinker to confirm if he is good with it as it stands- but who is it that manages the USI resources, and why is LqdCO2 even listed as a USI resource in the first place? (does USI use LqdCO2? If so, this was something I wasn't aware of...) Regards, Northstar

Alright, well the problem then is that LqdAmmonia is a resource shared by both RealFuels and KSP-Interstellar Extended. The density absolutely needs to be adjusted, though: the density is currently 604 kg/m3 in the document- the density of Ammonia even at its boiling-point (-34 C) is 682.778 kg/m3... The density I want to go with (I help develop KSP-I Extended, in the same way Regex helps develop RealFuels) is the density at -50 C: 702.1 kg/m3, but the density Regex seems to be favoring is either 682.778 kg/m3 (density at -34 C, the boiling-point: but many other cryogenic densities are already based off lower temperatures than boiling-point, LOX for instance) or 690.2 kg/m3 (density at -40 C, which is ambient temperature of Low Earth/Kerbin Orbit in RealFuels- but ambient is -80 or lower in interplanetary space or out by, say, Jool- which is why I want to go with density at -50 C, as it is the lowest temeprature I can get reliable density-data for...) The issue boils down to what to change the density of LqdAmmonia to, not whether to change it. All parties involved can agree that the current density of 604 kg/m3 is too low- as this is less than the density of Ammonia at 1 atm and its boiling-point... So, what I'm not clear on is this: can FreeThinker play the ultimate judge on this issue since he has Full Edit permissions on LqdAmmonia (and it is listed as a primarily KSP-I resource in the CRP working-document), or do we need to all come to some sort of consensus on the issue first? Regards, Northstar

I just wanted to summarize all the progress we've made so far on some resources used by KSP-Interstellar (or that will be in the near future according to FreeThinker- who wants to finalize the transition over to CRP densities for Hydrogen and Oxygen in the future if I understood him correctly...), just so it's clear I'm not trying to be difficult... Resources with good densities: LqdHydrogen (close enough for government work!) LqdOxygen (my point was that the value does *not* need adjusting- it is based off a super-cooled temperature below the boiling-point, as it should be) LqdMethane LqdCO2 LqdNitrogen Resources still in need of densirty-adjustment: LqdAmmonia (currently 604 kg/m3, should be 702.1 kg/m3- the density at -50 C) I'll try to compile a similar lists for costs (which I haven't spotted any issues with yet- but I'll want to double-check). And expand this list to include other resources as I check them more carefully. Regards, Northstar - - - Updated - - - Wait, so FreeThinker has permission to change the density for Ammonia to 702.1 kg/m3 if he's OK with this? Sweet! I think he will be fine with this change... Regards, Northstar

You are correct my dear sir. Could we just fix the density of Ammonia (a resource that gets much more use in KSP-Interstellar than in RealFuels- in the latter it has an inferior density/ISP combination than Methane and gives less Delta-V for most NERVA+spacecraft configurations than Methane anyways...) so that it's 702.1 kg/m3 before we do so? I think I've made some rather compelling arguments about why it makes more sense to store it at -50 C than at -40 or -34 C... All the other densities look good- so the only one I'm still currently worried about is Ammonia. Which is used by both RealFuels and KSP-Interstellar, although it gets much more use in the latter. An interesting note on the use of Ammonia in RealFuels, by the way. FreeThinker pointed me to some rather interesting Thrust/ISP tables for Nuclear Thermal Rockets a while back from the Atomic Rockets website... Apparently the Thrust you're using in RealFuels for Ammonia is much too low, as at the temperatures of a Nuclear Thermal Rocket your Ammonia propellant breaks down into Nitrogen and Hydrogen gas (so the number of gas molecules doubles) in the exhaust stream- significantly increasing your Thrust at no additional mass or heat requirement on your rocket's part... I'll have to get those tables/calculations to you at some point in the future. Indeed. You're right we shouldn't quibble too long over stuff like densities when 1.0 is getting so close... What is holding you back from adjusting the density of Ammonia to its density at a lower storage-temperature like we already do with Methane and Oxygen (even if I haven't managed to convince you yet that the density of LOX of 1142 kg/m3 does indeed come from chilling it further than its boiling-point along...) What sources, data, or support could I provide you with so I could quickly convince you of my point, and we can move on to more important stuff? Or are you absolutely not going to budge on this, and insist that I abandon this rather important discussion (considering Ammonia's value in KSP-Interstellar) for later? Also, what other things do we still need to look at or fix? Costs, I take it? Are we all good with naming, or are there any lingering issues there I'm not aware of? Regards, Northstar

Regarding LqdAmmonia, the most sensible temperature/density would be -50 C and 1 atm (702.1 kg/m3), not -40 C and 1 atm (690.2 kg/m3). That is because at -50 C you only have to cool/insulate the Ammonia by 10 degrees in LEO, but have to heat it 30 degrees in interplanetary space (or orbit of a planet further out from the Sun) in order to maintain it at this temperature. If you stored it at -40 C your heating-requirements in deep space would become substantially greater as you would have to maintain a 40-degree temperature differential from ambient (through heating and insulation) not a 30-degree one... At a lower temperature, LqdAmmonia is going to be denser. It's also going to be easier to store in the same rocket at LOX, Liquid Nitrogen, or LH2 as the temperature-differential between the propellants (how much warmer the Ammonia is than everything else) will be reduced- thus requiring less insulation between the different fuel-tanks inside the rocket... Both of these are of course very, very, very good things for a rocket- as they save mass on fuel tanks and insulation... (as well as heating-equipment, like I discussed above) You can find the Thermodynamics Calculator for Ammonia HERE. Finally, the density of LqdMethane ought to be based off -180 C and 1 atm, not its boiling-point (as you store Methane in the same rocket as LOX and LH2, both of which need to be kept substantially colder). This means its density should be 448.25 kg/m3. Once again, HERE is a link to the Thermodynamics Calculator used to find the density at -180 C. The currently-selected density is 448 kg/m3, so it looks like you guys actually took my advice on this one... Long story short- using density at the boiling points of cryogenics does not make sense. At the very least you're going to get a 10-20% decrease in density vs. a lower temperature. With something like LOX the difference becomes much more drastic- nearly a 90% reduction in density when storing at its boiling-point instead of -200 C... Regards, Northstar

@Regex, Starwaster (although I believe Starwaster has me on his "ignore" list- thus why he didn't know where the discussion of LOX density came from) I thought this was very clear. Those tanks weren't at the boiling-point of LOX. No rocket scientist in their right mind would store LOX at exactly its boiling-point due to its much lower density at this temperature... You store it at a dozen or so degrees (or a significant pressure-margin) colder than this in order to effect a more complete phase-transition from gas to liquid form... LOX has a density of 187.07 kg/m3 at its boiling-point at 1 barr pressure (-183 C). It had a destiny of 1142 kg/m3 at the temperatures and pressures it was stored on the Saturn V or Shuttle External Fuel Tank- as both vehicles stored it at significantly lower temperatures and higher pressures (pressure has almost no effect on density most of the time- but when it is used to effect a phase-transition... The thing about LOX is that it basically has a very gradual phase-transition: that is its thermodynamic behavior is significantly different at slightly lower temperatures or higher pressures than its boiling-point than right at it, leading to a large difference in density...) Once again, I'm not making this up. I not only already provided calculated density-figures at different temperatures for LOX , I also provided a link to the Thermodynamics Calculator I used to find them. You can check these figures for yourself. At 1 atm and -200 C you get a density of 1223 kg/m3. However at 1 atm and -183 C you get a density of 187.7 kg/m3. If you raise the pressure to 2 atm at -183 C you increase the density to 425.7 kg/m3 (you can much more easily effect the same more complete phase-transition by cooling the Oxygen a few degrees), but this is because you are effecting a more complete phase-transition not because you are compressing the liquid with pressure. If you raise the pressure to 2 atm at -200 C the density remains entirely unchanged at 1223 kg/m3 because the phase-transition is already complete. Regards, Northstar P.S. I hope you won't interpret this as a re-visit of my faulty "compressible liquids with pressure" argument from ages back. It's not. What I'm referring to is effecting phase-transitions (or as the case may have it, more complete phase-transitions) to increase density- in the same manner you can drastically increase the density of a gas at room temperature if you pressurize it until it turns into a liquid. It's not that you're compressing the gas with pressure- it's that you're raising the boiling-point until the gas enters a liquid state (which is always much more dense than the gaseous state). The most mass-effective way to turn a gas into a liquid is always to cool rather than pressurize it...

So it's screenshots from earlier versions of KSP you want, eh? Well I've got plenty of those... A Mun rover I made back in 0.22 TWO rovers and a lander on the mun, also in 0.22 A nice view of a space station I built back in 0.22 with Kerbin visible below it... A decent screenshot of one of the larger rockets I ever built in 0.22 A decent picture of a probe I sent to orbit the Mun and later land on Minmus back in 0.22 A lonely probe on the red planet (Duna). Again, 0.22 This is one way to get planes into space (planes I designed to fly on Duna back in 0.22- one of them eventually made it there, and could easily fly around, but had difficulty landing safely...) Or perhaps it's landings you want? (from 0.22, again) Or maybe a re-entry? (0.22) Spaceplanes are also fun. (0.22) (Same craft- but 2nd pic is after updating to 0.23) I couldn't resist posting a couple screenshots of this Low Kerbin Orbit solar beamed-power satellite... (0.23) Or perhaps just some good ole' enormous rockets are what you're looking for? (0.23) Helicopters are nice... (0.23) Especially when you add a rocket to the tail! (0.23) Here's that space station again- this time on its way to Minmus (0.23) Helicopter-based insanity (0.23) This helo' is carrying an entire mobile launchpad! (0.23) The ground-base (in the mountains west of the KSC) after it was developed a bit further.- and crewed by 6 Kerbals.. For a time, I used it for high-altitude launches to ease the fuel-requirements to orbit... (0.23) A Mun rocket heads for orbit. Yes those are a ring of BACC SRB's in the launch-stage... (0.23) Now THAT'S a big SSTO... For scale, those little tanks around the bottom? 1.25 meters. (0.23) A rocket about to leave Munar orbit (that's a space station in the background- but turned so you only see one of its fuel tanks...) 0.23 A spaceplane, orbiting Minmus, and preparing to head for Duna (0.23) And a refueling and orbital-recycling depot (0.23) A view of the Mun out a lander window (0.23) Regards, Northstar

You're not the first player to ask this question lextacy. I strongly recommend you check out the Guide to Off-World Refueling I wrote up last year, and have linked in my signature, to answer precisely these kinds of questions... Regards, Northstar

Moondog, welcome aboard first of all! I do hope you'll become an active and enthusiastic member of our community! KSP is, in my honest opinion, something that you can never play to exhaustion, and never has just one "right" way to play it (kind of like Minecraft- but much, much better). That was always part of the design-philosophy behind KSP, and something SQUAD should be and rightfully is proud of... KSP plays best with mods- when you get tired of spaceships, give submarines or airships a try for a little while, for instance (there are actually some rather excellent mods that allow both of those- linked in the text!) Or, when you want to try a more challenging experience, give Real Solar System and a more realistically-sized planet a try along with the RealFuels mod: it's so different it's almost like a different game. If you want to try near-term "hard" science-fiction gameplay, then the KSP-Interstellar Extended mod (which I help develop) is always a great place to start- there's nothing like building a Propulsive Fluid Accumulator in Low Kerbin (or Earth) orbit or taking an Alcubierre Drive to another star system (with another mod that adds a second star system!) And, of course, if you're more into "soft" science-fiction, there are mods that even add in the Starship Enterprise and working lasers! Regards, Northstar

Glad to have you aboard RandomActPG! I hope you'll become a more active part of the community now that you're finished lurking! Feel free to get share your screenshots over in the Fan Works section, or perhaps to try your hand at helping develop a few mods if you've got any programming skills (KSP-Interstellar Extension Config, which I help develop despite my lack of real modding skills, is in particular always looking for additional talent... ) Regards, Northstar