Greenhouse rewrite

[gotmachine]

State of things Greenhouses are :

• Unpractical because of the harvest system
• Badly balanced vs just taking more food
• Broken : the water input should have been removed with the humidity thing (and I'm not sure how well the WasteAtmo / Co2 auto switch thing works)

In the end the balance will always be something like :

• Less than mission duration X : packing supplies is more mass efficient
• More than mission duration X : using greenhouses is more mass efficient

Currently I think that X threshold is at about 25 100 years, which makes the greenhouse basically useless in all situations. I think the balance goal would be to make it at least a valid niche application meant for 2-3 years+ duration missions, ISRU capable bases or asteroid harvesting stations.

Idea

• I would replace it with a "setup mode" that you can toggle : while active you consume non-recovered ammonia and water, and that increase a "growth %".
• Food production is continuous, rate is scaled by the current growth % and light level.
• Food production require ammonia, water and CO2/WasteAtmo as inputs, and has food, waste water and oxygen as outputs, with mass conservation ratios.
• While production is going on, the "growth %" slowly decays.
• Launching a pre-grown greenhouse could have a large cost penalty.

That "setup time and consumed resources" system would be a way to reduce the greenhouse dry mass drastically while still having it not being a viable option for short term & non ISRU capable missions. Maybe a good balance would be :

• Setup time is 6 months
• Launching it fully filled with the water/ammonia needed for the setup phase put the threshold at about 5 years
• Launching it dry (assuming you will ISRU the water/ammonia) put the threshold at about 1 year
• I'm saying water/ammonia, but ammonia is quite hard to ISRU, so maybe put most of the requirement into water, or even maybe a different resource (ore > substrate ?)

Edit : If 1 greenhouse = food output for 1 kerbal, 0.5T dry + 1T of setup resources :

• Break even at about 30 years
• 7 years if you manage to ISRU the water/ammonia

We could buff it by having it being a waste > ammonia converter + a wastewater > water converter Have the inputs :

• waste (primary) or ammonia (secondary)
• wasteWater (primary) or water (secondary)
• wasteAtmo (primary) or CO2 (secondary)

And the outputs :

• oxygen
• water
• food

That would make it a lot more useful and flexible In exchange for the dry mass reduction, make it a not crewable part But 0.5 tons dry is really low... that not even the mass of the mk1 lander. I guess we are screwed because of KSP silly mass to volume ratios...

[ghost]

Perhaps there could be different greenhouse configurations, to simulate growing different "foods". I have proposed this in the past, I believe.

If you assume the "Food" resource is actually more representative of nutrition than food mass, different configurations could have different ups and downs: different growth times, different resource costs, different amounts of food output, et cetera.

[theJesuit]

This would complicate things quite a lot? Fast and dirty - lots of waste, but worth it for surface bases with mining/ unlimited supplies - long and efficient like a 4 to 5 year mission.

[Ballatik]

The manual harvest system is definitely problematic. I think it could be changed to either a normal process, or a stepped process (similar to eating) that would trigger one batch every X time. Most designs I've read about utilize a good bit of crop rotation instead of one big harvest every 2-3 months.

The proposed "Setup Mode" might be easier handled (both coding and gameplay wise) by making it possible for the "deploy" button to consume resources. This could simulate filling the hydroponics with water, or using in-situ dirt to fill planters and allow us to configure the greenhouse parts as smaller mass while still requiring the correct overall mass to get them operational.

In terms of balance, mass paybacks on what I've read range between 2-18 years, but that is only considering food output. There is additional mass savings when you consider the lessened need for CO2/Oxygen and possibly water filtration systems that the greenhouse can also provide. The lower paybacks tend to be smaller systems that are intended to supplement and not replace shipped food, such as algae bioreactors and the ISS VEGGIE unit (roughly 1 salad per month) The longer paybacks are for full-fledged greenhouses with more nutritionally complete crop selections.

Assuming that the wasteAtmosphere/CO2 switching works, it would be helpful to allow it to be configurable for multiple resources. Using waste + water, ammonia + water, or solely wasteWater as inputs are all viable, but currently we would need to configure the part to use just one of them at a time. If the switching doesn't work correctly, I would be less worried about losing that functionality than on losing the resources themselves. It would always be possible to simply add a small scrubber process to the greenhouse itself to compensate.

[lordcirth]

I wouldn't have a separate setup phase - just a module that turns inputs into outputs, but possibly with steps. Regarding balance, keep in mind that the greenhouse also provides both living space m^3 and green space comfort bonus for its mass.

[SirMortimer]

Anything that has a "realistic" break even time (7+ years) makes no sense for gameplay, it is exactly why I never brought a greenhouse on any one of my missions. Resupplying with canned food is just so much cheaper. So the greenhouse will have to be at least a bit OP to make any sense to have it in the game in the first place. To balance, the greenhouse (at least the current one we have in Kerbalism) will no longer be a habitat. It will be a food generator only.

Having processes that use alternative inputs (wasteAtmosphere and/or CO2) is something I'd like to avoid because that's quite tricky to handle internally (you'd have to consume different input resources at different rates for mass preservation, potentially have different side products... this can easily become very messy). I'd opt for giving the greenhouse a free scrubber (wasteAtmosphere -> CO2 converter) instead and have the greenhouse process run on pure CO2 instead.

I think along with the greenhouse we'll also have to think about the converters that we need to sustain it. Whatever it runs on should be mineable in places other than Kerbin.

[SirMortimer]

Looking good so far.

TODO

• remove light/radiation considererations from the part module. If food is to grow slower because of ambient radiation, that has to be handled by the process definition (modifier)
• module info

[NikeRocketeer]

Needs "plants" added to greenhouse module for crew comfort.

[captanredbeard]

I concur with the sentiment that the greenhouse would need to be short enough to setup quickly enough that it's viable for travel as opposed to food, but also long enough that canned food still remains the better option for shorter journeys. I'd say that if you were to launch a green house with existing plants and things already inside would take maybe somewhere from 2 months to a year or so at best to get to capacity.

An empty greenhouse? sure that would take quite a while but I'd very much prefer to make a greenhouse for space stations and deep space journeys in addition to enough supplies to wait till the greenhouse provides returns.

Also two different diameters would be great. maybe one small greenhouse module for feeding somewhere between 1 to 1.5 kerbals, and a larger one 1.5+ diameter to feed somewhere around two.