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Xenon ain't cheap - shouldn't ISRU make Xenon too?


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I seem to be a sucker for rescue Kerbals in expensive (to reach) orbits (ex I currently have 3 waiting rescue, 2 with craft retrieval, around 2M km from Kerbol) my rescue craft for this is a 3 Dawn engine 3 big xenon tank automaton with a claw heat shield and 3 chutes. But they are quite expensive with all that xenon and, if I could manufacture Xenon I could launch them with empty xenon tanks and fuel them at an orbital depot.

Given that the ISRU unit can make all the other fuels I feel that this is a little unfair. And if I can't get Xenon, how 'bout a Argon at a 25% ISP penalty?

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I don't think so. The liquid fuel in KSP is most likely hydrogen, and monopropellant is probably hydrazine, and oxidizer is oxygen. That said, you can manufacture all three of those with just water. (hydrazine being the exception, you need nitrogen) Xenon, being an element not present in water, cannot be produced like hydrogen or hydrazine.

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I can understand why one wouldn't be likely to find noble gas dissolved in Mun rocks.

But perhaps in an upcoming patch they can add a way to harvest resources from other places - e.g. planetary atmospheres. Such a device could also get Oxidizer from Laythe's atmosphere for example, and LiquidFuel (which appears to be hydrogen-based) from Jool's.

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I don't think so. The liquid fuel in KSP is most likely hydrogen, and monopropellant is probably hydrazine, and oxidizer is oxygen.
Liquid fuel is modelled after Aerozine50 and oxidizer after N2O4, at least insofar as thermal properties and overall isps, and both are pretty complex chemicals (creating them, at least, is complex), so I see no real reason why the ISRU converter couldn't pull xenon out of magical unicorn poop as well.
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Two main, complementary thoughts on this.

1 - How much dV does your 3 Dawn/3 big tank craft have? I'm guessing it's A LOT, and you really don't need that much to rescue Kerbals from orbit around Kerbin. It's probably cheaper to build traditional LFO-propelled vessels that have amounts of dV appropriate for the mission, than use all this Xe.

2 - The Xenon engines are primarily designed for very small probes on high dV trips (typically, 1-way). Basically, think Moho or Jool tours. What makes the Dawn engines so economical (grammar?) is that you can build SMALL high dV vessels, that are much less expensive to launch (small payload -> exponentially smaller vessels). They aren't designed for what you're using them for; they're designed for long distance trips without refueling.

Basically, it sounds like you're WAY over building for the mission you describe, AND you're using the wrong tool for it. I'd simply recommend re-evaluating your design instead of calling for game re-balances.

Edited by TestPilotTheta
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If you don't mind mods, Karbonite (the mod stock IRSU was made from) can make xenon from regolith.

I agree xenon should be a thing we can make but in the meantime, there's a mod for that, hehe.

I think you're wrong. It was made from Regolith, or some other ISRU mod RoverDude made. Not Kethane.

I agree Xenon production should be a thing. Would be a good alternative if you didn't want to do grindy contracts.

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Two main, complementary thoughts on this.

1 - How much dV does your 3 Dawn/3 big tank craft have? I'm guessing it's A LOT, and you really don't need that much to rescue Kerbals from orbit around Kerbin. It's probably cheaper to build traditional LFO-propelled vessels that have amounts of dV appropriate for the mission, than use all this Xe.

2 - The Xenon engines are primarily designed for very small probes on high dV trips (typically, 1-way). Basically, think Moho or Jool tours. What makes the Dawn engines so economical (grammar?) is that you can build SMALL high dV vessels, that are much less expensive to launch (small payload -> exponentially smaller vessels). They aren't designed for what you're using them for .

Basically, it sounds like you're WAY over building for the mission you describe, AND you're using the wrong tool for it. I'd simply recommend re-evaluating your design instead of calling for game re-balances.

Kerbol the sun which he said takes a lot of DV depending on the orbit.

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Kerbol the sun which he said takes a lot of DV depending on the orbit.

Ah, well then why do we need to refuel? It's going to cost more to get the Xe to that orbit to refuel with a vessel sent out there than it would to take the return fuel along the first time (outward bound trip should be down with a disposable stage).

And if that's the case, how does ISRU factor into this at all? You aren't gonna find asteroids 2 million km from the surface of the sun.

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Two main, complementary thoughts on this.

1 - How much dV does your 3 Dawn/3 big tank craft have? I'm guessing it's A LOT, and you really don't need that much to rescue Kerbals from orbit around Kerbin. It's probably cheaper to build traditional LFO-propelled vessels that have amounts of dV appropriate for the mission, than use all this Xe.

2 - The Xenon engines are primarily designed for very small probes on high dV trips (typically, 1-way). Basically, think Moho or Jool tours. What makes the Dawn engines so economical (grammar?) is that you can build SMALL high dV vessels, that are much less expensive to launch (small payload -> exponentially smaller vessels). They aren't designed for what you're using them for; they're designed for long distance trips without refueling.

Basically, it sounds like you're WAY over building for the mission you describe, AND you're using the wrong tool for it. I'd simply recommend re-evaluating your design instead of calling for game re-balances.

Ah, well then why do we need to refuel? It's going to cost more to get the Xe to that orbit to refuel with a vessel sent out there than it would to take the return fuel along the first time (outward bound trip should be down with a disposable stage).

And if that's the case, how does ISRU factor into this at all? You aren't gonna find asteroids 2 million km from the surface of the sun.

I think when the probe returns to the orbit of kerbin it can refuel with a space station that has been refueled from a xenon miner.

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Holy Kerbol, here's why you can't mine Xe: It would be a massive career mode exploit for cash.

1 unit of Xe is weighs 0.1 kg and is worth 4 funds, that means that at 50% mass efficiency (I think that's ISRU refinery's base mass conversion efficiency), you could refine 1 ton of ore into 5,000 units of Xe worth 20,000 funds! Compare that to LF, 1 ton of ore becomes 100 units of LF (1,000 kg ore x 0.5 kgs LF/1 kg ore x 1 unit LF/5 kg LF), which is worth 80 funds.

You'd be basically printing money.

I personally think this feels like an exploit. Maybe some players feel that this should be included to represent some kind of orbital manufacturing, but omission of Ore -> Xe means that the current game isn't balanced around this alternate source of income, and this would lead to a LOT of income: 100 tons of ore -> 1 million funds if you can get 50 tons back to the KSC. And that's before engineer bonuses (Not quite sure how they work).

That's my take on it, at least.

- - - Updated - - -

I think when the probe returns to the orbit of kerbin it can refuel with a space station that has been refueled from a xenon miner.

Then why does the vessel have 3 chutes on it? Sounds like that's going to the Kerbin's surface, not staying in orbit.

Edited by TestPilotTheta
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I think it should be able to make Xenon from Ore.

However, it would have to be slow, inefficient, and power-hungry in order to be balanced.

Efficiency: 1t ore = 0.05t Xenon or less

Not fast enough to keep up with the fuel consumption of even a single ion engine at full throttle.

Takes 2x as much power to run the converter when converting Xenon.

My intent here is to make it only really practical to refine Xenon at a planetary mining/refining site.

Additionally, it makes refining Xenon unprofitable.

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Ok, my explanation is ( as was pointed out ) that the ÃŽâ€V requirements are pretty high going in close to Kerbol (the sun) not Kerbin the planet. So far I have managed one mission that needed more than 12,000m/s in total and note that I have to retrieve whatever pod it turns out the rescue Kerbal is in as well. So if my vehicle did not have to pick up a Kerbal and his pod it would have more than 18,000 m/s of ÃŽâ€V.

As for the economics of ISRU and my mission, if I could launch my recovery craft with empty Xenon tanks and fill it with "Free" ISRU made Xenon it would cost less than half of what it does and the rescue mission would be profitable, as it is it about break even and given the long amortization schedule (300 Kerbin days for low Kerbol orbit). I have another rescue mission out near Jool, that will have a much longer amortization period. But as I wrote in my original post, I am a sucker for a cute rescue Kerbal, especially the way they purr and rub up to you, and eat the snacks right out of your hand.

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Just make xenon an atmospheric resource.

Yeah, it should be possible to make Xenon, but not with the ISRU. It should require a different sort of "miner" - one that skims the atmosphere of Jool, perhaps, before returning to a stable orbit for processing.

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I think you're wrong. It was made from Regolith, or some other ISRU mod RoverDude made. Not Kethane.

I agree Xenon production should be a thing. Would be a good alternative if you didn't want to do grindy contracts.

karbionite is not kethane. Karbionite runs on regolith

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It seems that OP wants ISRU xenon to resolve a problem that arises from an arguably inefficient solution to the mission goal.

Choosing a slow craft for a rescue makes the stranded Kerbals wait much longer than necessary, and the craft is so expensive that OP has trouble financing it.

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It seems that OP wants ISRU xenon to resolve a problem that arises from an arguably inefficient solution to the mission goal.

Choosing a slow craft for a rescue makes the stranded Kerbals wait much longer than necessary, and the craft is so expensive that OP has trouble financing it.

So what is the most efficient way to retrieve both the pod and kerbonaut from low Kerbol orbit? Given that this may easily require a total ÃŽâ€V of over 15,000m/s including gravity assist from Moho and/or Eve? What do you see as a more efficient solution?

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I'd go for nuclear engines.

Way too big a craft needed for that, remember this has to return the pod as well. Given that it only pays a couple of hundred thousand √ launching a vehicle built from something assembled in LKO at twice that cost doesn't seem effective.

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