Fish Pee and Sunshine

In the interim my posting, I've been reading a couple books from my list about Biosphere 2, and have been thinking about habitat breathing.

One way in which Biosphere 2 was designed to breathe, in the sense of regulating CO2 and O2, was through the controlled dormancy of its savanna biome. The grasslands were used to increase or decrease photosynthetic O2 production simply by watering.  This seems to me a very desirable way to moderate O2 levels, but I think would require some more quantifiable understanding than what I currently have.

Another of the key design features of Biosphere 2 was its "lungs", great bellows that helped to equalize pressure between the outside and inside of the enclosure. When air is heated, it expands. The Biosphere 2 enclosure is situatated within Earth's (aka Biosphere 1's) atmosphere, where the pressure varies with the weather. Without these lungs, Biosphere 2's glass would have shattered under pressure, and even without shattering, small leaks would be accelerated by pressure differentials. 

It occurs to me that a second possible use for lungs (not really explored by B2 to my knowledge) might to promote condensation or precipitation by dropping the pressure on command. Clearly, the structure must be designed to withstand the pressure differential. For most off-Earth designs this would naturally need to be the case anyway- expanding into vacuum would be trivial (where the worst case pressure differential is at compressed state). An undersea habitat would have the opposite problem (with the worst case pressure differential at the expanded state).

Additionally, a third potential use of lungs would be to create wind internal to the habitat. Again, this is not how the Biosphere 2 ones were designed to work, but I understand that the airlocks going into the lungs can be rather windy. Wind would useful to keep air from stagnating, and minimize need for fans to circulate air.

Biosphere 2's lungs are comprised of an expandable rubber membrane that rises along with the temperature, and a large metal counterweight that pulls the membrane back down and forces air back into the facility at night when temperatures drop. The system was designed to maintain a slight positive pressure, so that no outside air would ever seep in, but some could escape in the event of leaks.  My understanding is that this was determined largely to keep any critics at bay, but the gradual loss of air would also more accurately simulate conditions in space where this would inevitably be true as well. Losses were about 8% per year. I would imagine that with age, the leaking has gotten worse. Note, however that the ISS leaks at more than 20% per year. So without replenishment, presumably the astronauts would be breathing vacuum within only a few years. Clearly, hermeticity is something that will need to be vastly improved on for any isolated long term space habitats.

As I discussed a few posts back, the most salient feature of a truly closed ecosystem is hermeticity of the encosure. For a CELSS with stability, that means not only a very low permeability, but also a high reliability over a long time (multiple human generations at least). So last summer, I started researching materials with an eye skewed toward Martian resources and conditions and eventually stumbled into magnesium based cements. As I researched this further, I gradually convinced myself that a magnesium phosphate cement was THE ideal material for constructing Martian habitats.

• Nearly as impermeable as glass


• Even lower coefficient of thermal expansion, hence better reliability in environments with extreme temperature swings (like Mars)


• Sets at close to freezing (0°C) temperatures, addition of antifreeze could potentially even lower that to -60°C


• Two part aqueous slurry chemistry requires only modest energy, but could be used in autonomous deposition (i.e., remote 3D printing)


• Two part aqueous chemistry also has some repercussions for delivery that invoke biomimicry

In late September, I found out about the New Worlds 2016 Symposium, and submitted an abstract, which was accepted, then put together a paper and ulimately presented in early November in Austin. I also raced to file a provisional patent before submitting these publications, and planted the seeds of a new venture. Those venture seeds are germinating at my Cerambotics website. As of the date of this post, New Worlds still has not published the papers, or videos of the presentations. My slides can be found at http://cerambotics.com/NW2016presentation.html.

The mostly unasked question I infer from others versed in this topic of ISRU hab materials is how do I rationalize using wet chemistry when most other space-hab construction efforts are currently focused on sintering methods? I should say that I am a proponent of developing sintering methods in general. I think sintering is a grand idea on the moon and asteroids, where water is likely to be limited, but because of the low gravity in these scenarios it will necessarily be high temperature sintering to make up for low pressure. High temperature means high power. On Luna, and asteroids inside Mars' orbit, there is abundant solar energy to tap into. At Mars, however, insolation is only half that at Earth orbit, and on the surface, it is further attenuated. Without tethering to vast surface solar arrays or orbital power beaming, it is unlikely that a large structure could feasibly be sintered on Mars.  At the same time, water is expected to be abundant on the surface, or rather just under the surface. While temperature and pressure conditions on Mars lead to sublimation of surface water, indications point to an abundance of permafrost at several inches below. The water content here will need to be addressed even for sintering this material, as it will create voiding in the sintered material if not first extracted. Better to use it, especially if there is a way to build habitat walls with less energy. Now, with my proposal, there must be a way to keep the aqueous slurries from freezing at Arctic temperatures. One solution is to just add heaters to the plumbing. That adds energy requirements, albeit nowhere near to what sintering needs. Another solution is antifreeze. Fortunately, one of my slurry constituents already acts as an antifreeze: phosphoric acid. I have some other candidates I am investigating for the magnesium slurry. One of those candidates is a material already identified in Martian regolith: perchlorates, which are known to lower (in the right amounts) the freezing point of water to nearly -70C.

So to summarize my rationale, there are several reasons driving me away from sintering and some good indications that wet chemistry is actually very feasible on Mars.

I read Sue Hubbel's Book of Bees and learned a bit about bee behavior- I'll certainly need to reread if I ever get another colony. It's written in an autobiographical style, covering beekeeping over the course of a year, so captures most of the major points in starting and keeping bees, and processing honey. Ms. Hubbels methods are more geared toward commercial production, but she clearly has a naturalist's inclination.

Also read both the books on my list covering Biosphere 2. The Allen one was not impressive, but I enjoyed Poynter's book and have already posted on many of the things I gleaned from it.

I decided to read Manmade Closed Ecological Systems by Gittelson, Lisovsky, and MacElroy in lieu of Eckart's Spaceflight Life Support and Biospherics (which I have also ordered). Still reading, but so far very impressed with the depth of research covered on CELSS.  Have already learned of some new efforts to look into including the European MELISSA work.

The last one on my list is Cowan's Microbiology book.  I have not even procured it yet, but am excited about it. Everytime I have run into a design problem and asked myself how nature does it, I've come up with great ways to solve the problem. I'll have much more to say about biomimicry in a future post.

This summer reached an all time low in CELSS productivity for me. Not many blossoms survived the late spring freezes this year.  We had about a dozen strawberries, a dozen cherries, a dozen blackberries, no peaches, one plum, and three asian pears. Got a couple dozen pea pods and really straggly lettuce.  None of the beans, squash, peppers, cucumbers, spinach, kale came up.

Most likely this is because it went from freezing to baking hot in June, and my irrigation system stayed off until mid July when I finally got a chance to fix some of the leaks.  It seems like we were scarcely home this summer.

Due to health concerns over the creosote containing railroad ties making up my 90% completed wicking bed, we had the ties removed in May.  I haven't had the heart or time to rebuild with anything else so far.

Black soldier flies got a slow start as well. Ordered three batches, two came DOA due to the heat and postal stupidity.  Quail composter keeps flooding. I managed to rid my mouse infestation, but looks like they are back this last week.  Planning to harvest quail before winter, so I don't have to deal with it during the cold season.  

I did install a solar panel for circulating the quail water, but the four 12V batteries I had were all bad.  Unfortunately, that was the extent of my so-called "Summer of Solar".

On the bright side I did make some progress on my reading list, and got to meet Paul in person, when he stopped by on his travels eastward.  In addition to setting up a new Osmobot for beta tesing, we killed a bottle of lousy wine and traded some stories.

Also on the positive front, I have found my Mars wonder material and am developing it for potential commercial use.  Perhaps more on this at a later time.

I've had dreams about going to Mars, and have spent the last few days thinking about some of the other technical* challenges (aside from system level CELSS development) that might be important for setting up a habitat there, and enroute.  Since I am a materials engineer by trade, I'll confine myself to that arena.

*A few years ago at the first 100 Year Starship Symposium, I asked a panel of economists if they thought the challenges for such an interstellar mission were more technical or more fiscal. They all thought economics were the greater challenge. Naturally. Being an engineer, I disagreed :)

Shielding Materials

Shelter from the traditional elements is not so much the concern on the way to Mars or even on the suface (contrary to The Martian film). Shielding against radiation and shielding against micrometeors is however required.

The Earth itself uses a magnetic field to deflect much of the ionizing radiation, but it is unlikely artificial magnetic shielding will ever be economical without cheap fusion energy to power it.

Readily available regolith (Martian dirt) also would work on the surface where reaction mass is not a concern and transportation costs nil. Regolith thick enough to protect against radiation is generally sufficient to protect against micrometeoroids. However, the technology to make it structurally load bearing would be nice.  Sandbag construction, brickmaking, and thermally compatible concretization chemistry are all options. That said, I somewhat favor the burrowing approach, as I think it is more ultimately extendable toward colonizing asteroids. Tunneling equipment on Earth however tends to be quite complex mechanically, and very heavy. A swarm of self replicating robots seems to me the best solution, if prepared ahead of time. Self-replication implies ISRU mining, refining, and manufacturing. These are all worthy of another post at a later date.

For the trip there, fortunately one of the best radiation shielding materials is water. Rocket fuel also works pretty well. So does most biomass, including manure, compost, or radiation tolerant plants. Actually anything containing hydrogen. Which is good, because we need all those things anyway. Unfortunately, these things all generally outgas horrendously, which if not contained will vent to space and cause the system to lose mass over time.

Hermetic Materials

Most everything leaks. The saying goes that nature abhors a vacuum, but in space, the opposite is true. Gases diffuse through solids. Liquids evaporate, solids sublimate. Especially at higher temperatures and under bombardment of solar and cosmic radiation.

The more traditional approach to containing an atmosphere is to use a solid barrier sufficiently thick to mitigate diffusion, provide structure, and shielding. Aluminum has been the material of choice for most of the space era due to the optimal combination of strength, weight, and cost. Composites are starting to be used more however. Glassy ceramics tend to be the best, and also have low thermal expansion, which will certainly be a consideration for Mars' 100 degree per day temperature swings.

In the midst of all the graphene hype, one of the recently discovered properties of this material is that it is exceptionally impermeable to hydrogen gas. H2 is one of the hardest gases to contain (it causes hydrogen embrittlement in most metals, making it also very dangerous to contain), so this is great news for the hydrogen fuel cell folks. And for space enclosures. Unfortunately bulk production is still years away. The application of such a material would likely be in the form of a composite sandwich layer between polymers, or a coating applied to a structural metal shell, or sandwiched between walls of Martian brick.

Lighting and Power Technology

Plants and algae require light.  Despite all the difficulties involved, I find myself still attached to the idea of greenhouses on Mars, or at least light pipes collecting and admitting natural sunlight to a subterranean habitat. Bulk glass production would be needed to accomplish this. Relatively thick windows would be needed just to protect from UV and other radiations. I've also considered a layer of water as a potential solution, but red wavelengths have difficulty penetrating more than a couple meters of water, and the reds are required for most photosynthesis. At least two meters of water and glass combined would be needed for radiation protection. Mars is already receiving less PAR insolation compared to Earth due to its added distance from the sun. Rad hardy plants might be bred (or maybe genetically sampled from Chernobyl...) to provide an outer canopy for a less shielded greenhouse. But as Biosphere 2 found, algae really likes to grow on windows where condensation forms. Due to the temperature differential, this would be nearly inevitable.

It's therefore likely that the first generations of Martians will utilize artificial lighting to great degree. This will require power, either from geothermal sources, photovoltaic or nuclear. In transit, PV has a clear advantage, but I somewhat prefer the latter for Mars itself. LFTR reactors seem to be a good safe solution for this in my opinion, because waste heat could be used for keeping warm on a planet where the average temperature is on par with dry ice.

LED grow lights have come a long ways recently and are probably the best current solution. However, humans will require broad spectrum lighting for psychological and health reasons. Not to mention, for seeing stuff.

Conclusions

Ultimately, I like to think of the holy grail of space materials as something very like cell walls/membranes in function, combining the following: hermetic structure, visible light admission, radiation shielding ideally absorbing the energy and converting it to energy. Also,self repairing and easy to fabricate from readily available materials. It would be ideal to have a single wonder material to simultaneously perfrom all these functions, but that is not likely.This is a technology that will likely need to evolve, and will probablly be a composite of many materials, strategically layered.

I've been playing with instrumentation/automation for some months now.


Here's where I think it would be useful in my current situation:

• Systematic quantification of experimental data.
• Checking vital signs in the aquaponics water: pH, temperature, dissolved oxygen (DO), ammonia. Tracking water level in the sump, and in each of my grow beds is also a critical function as it evaporates quickly here, and bell siphons go out of whack easily. Running pumps dry is not a good thing.
• Automating grow lights, to provide consistent light cycles.  Timers can generally do this, but can't be changed remotely.
• Automating heaters.There are temperature controllers readily available, but it would be difficult to control the temperature according to DO levels for instance.
• Fish feeding. Again, there are timer based fish feeders, that can go a week or so, that I am currently using to allow myself to go on vacations, but without the capability to remotely turn off when for instance ammonia levels spike.
• Motion sensing to turn grow lights off in the presence of children.  My wife is concerned about the UV spectrum of the grow lights damaging their eyes.
• Controlling temperature/heat lamps on the outdoor quail.
• Monitoring water levels for the quail.  I've had 2 or three instances this winter where they ran out of water for a day or so because of frozen hoses in the circulating system I've set up for them. Quail stop laying for days if they are without water for even a few hours.
• Automated feeders for quail and rabbits

 


Here's where I am:


 


Grove system


Based on some of the instructables  reviewed I settled on an Intel Galileo board with a Grove cape and sensors.  The Grove system is modular and fairly extensive but lacks a good way to measure DO and ammonia.  A pH sensor exists but is not really designed for continuous measurement. The temperature sensors are all (AFAIK) for air measurement, The light sensor is broad spectrum. The Galileo itself is not as well supported as I'd like, and it turned out the CO2 sensor I bought does not work with Galileo. These are the sensors/controllers I ended up using:

• Water sensor
• Moisture sensor
• Light sensor
• UV sensor
• MQ9 gas sensor
• Motion sensor
• Relay
• LCD (to locally display measurement data)
• Button (to control which measurements are displayed)

I wrote programs in both Python and in Javascript (node.js), to read and send data to a web server (viewable at https://celss.net/sensor/display.php).  The javascript has since stopped working, and I suspect buffering issues in the request commands. I am looking to reinvoke my Python program and move it over to a Raspberry Pi platform at some point as I expect it to be more stable there, and I much prefer Python as a programming language.  I also considered using a spare Beagle Bone Black board, but the Grove cape for it is very limited in IO.




 


OsmoBot


Paul Holowko was kind enough to let me test out one of his beta units. I was very impressed with the water level sensing, once I had it hooked up correctly.  The unit I tested did not have DO/pH sensing capabilities, but his newer models do, using a superior optical method that does not need chemicals to run. The ((http://OsmoBot.com|OsmoBot)) light meter senses red, green and blue spectrums separately, so you can measure which part of the spectrum needs supplementation (generally on the red end I expect) to achieve ideal PPF. The ((http://OsmoBot.com|OsmoBot)) requires some setup with wifi, but then posts measurement data to OsmoBot.net, which shows up nicely on most devices including my android phone.


I did have some problems with the ((http://OsmoBot.com|OsmoBot)) reconnecting after dropped internet connect (due to crummy cable service, and possibly a router that took it upon itself to update firmware in that timeframe). Discussing with Paul, it sounds like he has largely solved this problem with updates to firmware on the OsmoBot.  The main thing the ((http://OsmoBot.com|OsmoBot)) didn't provide that I wanted for my situation was expansion and customization. 


 


Conclusions


A good DO measuring system by itself costs a few hundred dollars, so the OsmoBot system is a pretty good deal at the $600 price point. I spent about $200 on Grove sensor kits and a Galileo board, and arrived at different capabilities with some overlap of the OsmoBot system. I also spent a lot of hours programming which while it's not my day job, I do have some experience with. My wife, who is a professionally consulting programmer spent a few hours helping me troubleshoot problems also. Considering her going rate for consulting, the cost of my custom system would no doubt far exceed the cost of an OsmoBot.  All that considered, I learned a great deal about the IoT world in this venture, and will probably continue playing with my custom system at the hobbyist level, at least until I can get my oldest son trained to take over instrumentation so I can go back to focusing on system design.

This is an excellent paper for providing a high level overview of how to design a life support system. It of course retains the standard NASA bias against fully bioregenerative systems on the basis of heritage, weight, and complexity. Below are the highlights of the paper with my detailed comments for each section.

LIFE SUPPORT SYSTEM DESIGN

1. Life support subsystems are defined by function - oxygen generation, carbon dioxide removal, wastewater processing, etc. 2. The basic architecture of life support systems is stable. 3. Life support systems will probably evolve one subsystem or component at a time. 

I absolutely agree with this, with the caveat that biology tends to be multifunctional, so that when replacing for instance static food supplies with agriculture, the need for mechanical CO2 removal becomes negligible. 

HUMAN METABOLIC NEEDS 
1. A crewmember requires about 5 kg (11 Ibs) of drinking water, hydrated food, and oxygen per day. 2. Water for drinking and food preparation dominates. The 5 kg is roughly 1/2 water, 1/3 hydrated food, and 1/6 oxygen. 3. Dehydrating food can reduce food resupply mass by 2/3. 4. Food solids provide about 5 Calories per gram. 5. Respiration produces about 3.4 Calories per gram of oxygen consumed. 

Presupplied dehydrated food is not sustainable in a closed system, except as a method of storing food grown in the system. 

 

HYGIENE WATER REQUIREMENTS 
1. The hygiene (washing) water is typically 25 kg/day, 5 times the 5 kg/day mass of oxygen, hydrated food, and food preparation and drinking water. 2. Including hygiene water, a crewmember requires about 30 kg of water, food, and oxygen per day. 3. The hygiene (washing) water is typically 10 times the mass of the food preparation and drinking water. 4. The minimum consumed (food preparation and drinking) water is roughly 1/3 of nominal. 5. The minimum hygiene (washing) water is roughly 1/3 of nominal. 6. Two-thirds reduction in total water use, to 10 kg/day, is possible. 

Lesson being that lots of water is needed, and not just for human metabolism and hygeine. NASA missions generally try to minimize water due to weight considerations. Water, however, can be used for a lot of things in a system including mass transfer of micronutrients, radiation shielding, thermal mass and heat transfer. At low temperatures, ice can even be used structurally (e.g. pykrete). A large water buffer provides system stability, and should be integral to the system design.

ATMOSPHERE LOSSES 
1. Nitrogen resupply is needed to make up atmosphere leakage and airlock loss. 2. The daily atmosphere loss due to leakage and airlock operation can equal 2-3 kg/day. 3. Leakage and airlock loss of oxygen can equal 10% of the metabolic use of oxygen by the crew. 

I have never understood why folks insist on using the day as a measurement of time. A "day" is ambiguous depending on planet and context: it could be a full cycle of day/night, just the diurnal period, a mission day, a workday, or a period of 24hrs. Makes more sense to just reference the number of hours, in this case ~100g/hr, although it is probably heavily influenced by use of airlocks, so that should be a separate measurement (e.g. 500g/use).  

Clearly, there is opportunity for improvement in airlock leakage, which I think is largely addressed in the latest Z-series suit designs. 

 

CREW SIZE 
1. The mass of oxygen, water, and food consumed increases directly with crew size. 2. The size and cost of the life support system increase with crew size, but less than directly. Some economies of scale are possible. 

Buffer, buffer, buffer.

 

DURATION 
1. The mass of oxygen, water, and food consumed increases directly with duration. 2. The processing capacity of the life support system hardware does not increase with duration. 3. Longer duration missions require hardware with higher reliability, maintainability, and repairability, more spares, and longer life. 4. The optimum amount of recycling (of oxygen, water, and possibly food) increases as mission duration increases. 5. For duration beyond a few weeks, regenerable technologies should be used to recycle water. 
6. For duration beyond a few weeks, regenerable technologies rather than lithium hydroxide should be used to remove carbon dioxide. 7. For duration beyond a few weeks, oxygen regeneration should be used. 8. For duration of several years or permanent bases, food production might be considered. 9. Longer duration missions require more waste processing for stabilization, storage, and sanitation. 

It should be apparent that for long term habitation of space, bioregeneration is essential. Why this is not a higher priority for NASA, I don't know (and is why I created the website)!  Hardware sparing is another topic. For self sufficiency, it implies some basic manufacturing capabilities.

DESTINATION 
1. Planetary missions should be designed for significantly reduced mass. 2. Earth orbit missions should not be designed for minimum mass. 3. Long travel time requires closed loop life support in microgravity. 4. Longer resupply delay requires increased storage and spares, and higher system maintainability and reliability at a remote base. 5. Life support systems must operate in microgravity and possibly in planetary gravity. 6. Planetary dust and atmosphere and soil chemistry must be considered. 7.In situ resources can be used to reduce resupply and recycling needs. 8. Design cost analysis should consider the total mission cost, not only development or launch or operations cost. 9. Higher resupply cost justifies tighter atmosphere leakage and loss specifications. 

I'm not sure I agree with the first statement, particularly if the interplanetary transit reuses a vehicle/habitat. Planetary surface operations should leverage ISRU.

There is little reason to design a habitat for sustained microgravity. Earth biology is evolved for gravity; we should be designing our systems with centrifugal simulation for the foreseeable future. Biology may eventually adapt to microgravity, but it will be gradual, and for specialized use. 

Soil chemistry optimization will need to be tailored constantly based on local conditions. 

PLANNED OPERATIONS 
1. EVA suits typically use nonregenerable life support. 2. One EVA in an open loop suit requires about 3 kg of LiOH and 5 kg of water. 

EVA suits should return wastes to habitat for recycle, rather than venting them.

SYSTEMS INTEGRATION AND RECYCLING 
1. Full closure is impossible. 2. Some resupply is always necessary. Some regeneration and recycling is usually economic. Life support commodities should be provided by a cost-effective combination of resupply and recycling. 3. Waste should be recycled only if we need the recovered resource. Otherwise, we should stabilize and store or dump the waste. 4. The cost-effective amount of water recovery depends on the water balance. 5. Fuel cells or a hydrated food supply can provide significant water. 6. We can generate oxygen by using electrolysis rather than by reducing carbon dioxide if excess water is available. 7. We should reduce carbon dioxide to recover oxygen if the system must recycle most of the water.  8. Only 80-90% of the crew oxygen can be recovered from the carbon dioxide. 9. Metabolism of food produces about 1/3 kg/day/crewmember more water than consumed. 10. The missing 15% of the crew oxygen can be recovered from 0.1 4 kg of water. We still have about 0.2 kg/day/crewmember of excess water. 11. If dehvdrated food is supplied, the water recycling system can loose only 0.7% without resupply 12. If hvdrated food is supplied, the water recycling system can loose 5% without resupply. 13. The harvest index of plants grown for food is roughly 50%. 14. If we grow roughly half the food, plant growth will supply all the oxygen required by the crew and remove all the carbon dioxide generated by the crew.  15. The fraction of the food that must be grown to provide all crew oxygen and absorb all crew carbon dioxide equals the harvest index.  16. We need to oxidize solid waste to produce carbon dioxide if the plants produce more than roughly half (the harvest index) of the crew food.  17. If the plants produce all the crew food, we need to oxidize all the waste.

The 2nd Law of Thermodynamics makes the first statement true on a theoretical basis. Indeed, the Earth itself is not completely closed system, as it it losing hydrogen and other gases, but on the practical level it is closed. As I've asserted before, system stability must be measured in terms of time. The Earth's ecosystem is stable on the order of millions of years.  A viable CELSS habitat must be ulitmately stable on the order of multiple human generations.

Wastes should nearly always be recovered, although when a habitat is being generated from local resources, the proportion of elements may not be ideal for the habitat, so there will necessarily be waste from these (and any ISRU) operations. 

Regarding 14-17, I believe this imbalance can be addressed by having other animals in the food chain (rabbits, quail, fish, crustaceans, worms, BSF larvae, etc), as they can provide the additional CO2 needed by the plants and help to oxidize the fibrous plant parts indigestible by humans. 

HARDWARE AND TECHNOLOGY 
1. It is likely that the life support systems for the next human mission will be similar in concept and technology to those developed for the International Space Station (ISS). 2. They will be physico-chemical rather than bioregenerative. 3. For planetary missions, ISS-like physico-chemical subsystems must be reengineered for minimum mass. 

Only because that is where the dollars and effort are going.

The new year brings new resolutions.  Among mine is a goal to read up more on the previous works in the CELSS field. Here is my list for 2016: 

 

Jones, H., "Design Rules for Life Support Systems", 33rd International Conference on Environmental Systems (ICES), 2003.

Eckart, P., "Spaceflight Life Support and Biospherics", Microcosm Press, Torrance, CA, 1996. 

Allen, J. "Me and the Biospheres" Synergetic Press, 2009.

Poynter, J. "The Human Experiment: Two Years and Twenty Minutes Inside Biosphere 2", Thunder's Mouth Press, 2006.

Cowan, M., "Microbiology: A Systems Approach"  McGraw-Hill, 2012.

Hubbell, S., "A Book of Bees" Houghton Mifflin,1988. 

 

Motivated by a) dislike of mowing grass, and b) desire for more vegetables, I have finally starting on my summer project of building a grow bed to the yard. Yea, I know it's October. I procrastinated having to move sprinkler heads, but that part is now behind me, so now it's just a matter of stacking railroad ties. I have also created another hugelkulture berm, just awaiting a load of manure. These activities have brought me back to the topic of soil bed reactor design.

Paul also recently posted some good info about soil drainage tiki-view_blog_post.php?postId=3960

'Are you going to tell me,' said Arthur, 'that I shouldn't have green salad?'
'Well,' said the animal, 'I know many vegetables that are very clear on that point. Which is why it was eventually decided to cut through the whole tangled problem and breed an animal that actually wanted to be eaten and was capable of saying so clearly and distinctly. And here I am.'

-Douglas Adams, The Restaurant at the End of the Universe

• Onion: Onions should be picked when the stem falls over


• Radish: You should be able to see the top part of the radish root pushing itself up out of the ground a little bit. If it looks about the size you expect that specific radish variety to mature to, they should be ready to harvest when they reach that size. Sometimes you have to scrape dirt. If your radish is all leaf and no radish, then that's usually a planting/thinning issue; you need to thin them to the proper spacing while they are very small.


• Potatoes: New potatoes should be ready for harvest after 10 weeks. Harvest all the potatoes once the vines die so they don't rot in the ground.


• Tomatoes: Usually when the turn red, but some of the heirloom varieties are different colors (yellow, purple)


• Peppers- the problem with peppers is that some you want green, some yellow and some red, and unless you know what you planted, you aren't sure when to pick.


• Broccoli: Monitor daily when flower heads begin to form in the center of the plant, check its growth every day. Harvest broccoli while the tiny buds are tightly closed. If the buds begin to swell or show yellow (the flower petals), cut the head from the stem right away, no matter how small it is, because the opening buds have a mealy texture. After cutting the main head, leave the plant to grow bite-sized side shoots in the axils of the leaves. 


• Eggplant: Sort of like squash, they just tend to get bigger the longer you wait. Until they go soft.


• Squash: There is some leeway with squash. Generally anytime after they are big enough to be worth picking  but before they get too soft.


• Strawberries: Pick when red.


• Beans: The best time when to pick beans is while they are still young and tender and before the seeds inside are visibly evident when looking at the pod.


• Melon: Research of the literature (i.e. Google) tells me that you wait for the stem area to get soft.


• Kale, Spinach, Lettuce: Pick leaves sporadically as needed.


• Carrots:carrots can stay in the ground for months and keep on growing. Just  pull the carrots you need for dinner. You may as well store them in the ground as allow them to go limp in the fridge!


• Lovage: Pick when you need it. 


• Rhubarb: Pick when the stems turn red. Don't confuse with swiss chard.

Much of traditional gardening lore is based on weather and seasons. A CELSS will ideally be more consistent weather wise. The incorporation of seasons into a CELSS is a topic for another post...