Fish Pee and Sunshine

Of Rabbit Holes, Complexity, and Resilience

Greg Vialle Friday 04 of February, 2022

It’s been awhile since last I blogged here. I recently finished listening to S. Page’s Great Courses Complexity which reminded me of a couple of books I read last year by N. Taleb (Antifragile, Black Swan, etc.) which inspired me to start philosophizing again about the long term future of humanity. As I started thinking more about what it was I wanted to explore with this post, I came quickly to realize that I was down a rabbit hole, and speaking of rabbits…

The Tale of the $500 Free Rabbits

At the beginning of COVID, my wife, worried that the kids would not be getting to play with friends for awhile, asked if I would be ok getting rabbits again. I immediately recognized this as a trap. Last time I said yes to rabbits, they instantly became my responsibility. Just like with the kids.

Hence, I wisely said “No way.” I was outvoted. A few days later, wife sent me to pick up free rabbit #1. A few days after that, she brought home free rabbit #2, a young male. A week after that, rabbit #1 developed a limp resulting in a $100 vet visit where we confirmed it was a doe (female). 30 seconds later we had a litter of baby rabbits.

Ok, that’s an exaggeration, it didn’t happen until fall, but we ended up with 5 rabbits in the house. All. Winter. We managed to get rabbit #2 neutered before a second incident. However, one of the new bunnies was also born with outside genitals, so it wasn’t long before we were up to 15 rabbits. This situation was not a surprise to me, and I urged my wife at every juncture to find a new home for boy bunny. Eventually she did, but not until after another litter of 5. To her credit, she found new homes for 13 of the bunnies, and neighborhood cats took care of the rest.

I learned why it is called animal "husbandry". My involvement reluctance was deemed irrelevant. Over this last summer, I converted the kids playhouse into a rabbit enclosure. Also over the summer I experienced the supreme satisfaction of removing botfly larvae from rabbits, but not until after another diagnostic vet visit costing $400. In December, rabbit #1 burrowed out of my fine enclosure and was taken by a fox (according to surveillance system). We are now at 3 rabbits. Rabbits running around the yard is incidentally why gardening efforts the last two years have been minimal.

Resilience

Our rabbit colony continues to exist because mama rabbit sacrificed herself by bolting, forcing the fox to chase her instead of going into the enclosure and killing all the rabbits as foxes often do with prey in captivity. Whether this altruistic final act was intentional or instinctual, it demonstrates the difference between individual and collective success. If our primary goal was to maintain colony size (instead of letting children learn responsibility and empathy), I could have kept the rabbits in separate hutches, to separate the potential points of failure and limit risk. This is the classically metaphorical egg-basket distribution, or what I like to call "spatial diversity". It is by no means the only form of diversity, but certainly one of the most important in a universe with both causality and locality. Rabbits are also the very archetype of temporal diversification, aka, evolution.

For me, one of the most compelling reasons to go to space is to improve the resilience of life in general and the human race in particular. An interstellar starship represents the capability for life and humanity to be a multistar phenomenon, a significant step in ensuring the indefinite extancy of life in the universe, prelude to overcoming entropy itself. For the purpose of concision, let's henceforth call the state of humans colonizing another star system K2 (Kardeshev_Level 2).

This of course begs a definition for resilience, and a way to measure it. In materials engineering, resilience is the ability to recover from strain energy. It is the area under the linear part of the stress-strain curve.

In common parlance, resilience (of character, for instance) has a similar definition: the ability to recover from negative events, requiring some combination of (character) strength and adaptability. In materials, resilience is an energy per unit area calculated through experimental measure of elastic stress (σy) and strain (εy) limits. For the ESH state, we need to regard the collective resilience of the human species, not the resiliene of each individual. Simplistically, one could measure the total population times the distance spanned, but better Yet, that does not even come close to capturing the concept of resilience as it applies to the human collective, much less the ecological complexity that is Life. Complex systems contain diversity. There is a distribution of failure points, and the components interact and influence one another. In Scott Page's "Complexity" course, the analogy of 'landscape' is used. An easily optimizable system might look like a mountain. A less simplistic system might be like a rugged mountain range with many peaks. But a complex system is one that is constantly changing because Mt Fuji is in an arms race with Mauna Loa and every other terrain feature. This is economics and ecology. When we oversimplify our models, things like unpriced externalities can wreak havoc. For resilience, tipping points are critical. If every component of a system is uniform, then the only failure mode is catastophic like the infamous One Hoss Chaise; evolutionary improvement is impossible.

Design for Failure

In material science, fracture mechanics is a good example (I hope other materials engineers will forgive my oversimplifiation) of how defects in a crystalline structure help to arrest crack propagation by absorbing strain energy. Work hardening helps to create these defects which ultimately buffer against more catastrophic failures. In a related fashion, within linguistics the inefficiencies of a language actually serve to make it more able to convey meaning. Homonymns (words that sound alike but have completely different meaning) not only open up the field of pun humour, they provide a degree of error checking at a meta level of communication. Now, ifI haven't completely made you scratch your head at what any of this has to do with ecosystem, let me spell it out: complexity is an absolute requirement if you want resiience, it cannot be designed, but it can be designed for.

Biosphere 2

Greg Vialle Saturday 14 of December, 2019

For Thanksgiving this year we took a family roadtrip to Arizona. On the way back home, I managed to bamboozle the wife and kids into visiting Oracle while racing against the snowstorm chasing us eastward. Thus I was able to realize my years long ambition of checking out B2 in person.

2019Q3 Update

Greg Vialle Tuesday 15 of October, 2019

Things have progressed some since I quit my day job a little more than a year ago to pursue a business venture in 3D printing. Some of the progress is possibly at the expense of said venture, but a guy needs his distractions.

Outside

Not much with garden this year, as my wife wanted to give it a try, and had even less success with early indoor germination than me. My perennial asparagus is in its second year in the wicking bed, which I finally finished spring 2018. Unfortunately, I did not design the water inlet well, so it pulled too much water pressue from the rest of the zone, and overflowed every watering, leaving the other garden area underwatered. The dill in the hugelculture garden didn't seem to mind, but never got any carrots, peas, or cucumbers to come up. Strawberry patch was pretty sad this year for same reason. Last week, I got around to putting in a pressure regulator on the wicking bed, hopefullly that fixes the watering issues. There is still kale, spinach and zucchini (which I covered during the freeze last week), but I've turned off the sprinkler system for the winter.

There's been some turnover in the tree department, since last I reported here. Currently there are a number of raspberry and blackberry bushes with quite modest yields, probably due to inconsistent watering. The peach tree I planted when we bought the place has had bumper yields two years in a row now, narrowly escaping (in part due possibly to my use of ropelights in the spring) the annual Mother's Day snow strom we seem to get every May. My plum tree died back a few years ago, but came back pretty strong this year from the root stock, so at least I have something to graft onto. Same story with an ornamental cherry tree. However, I've only had success in grafting one apple branch (of dozens tried) onto one of the crab apple trees. No fruit this year, due to the May ice storm, but got about five apples last year. Only one of several paw paws trees I've tried has taken. I've yet to see any fruit from it, although I did get a few blossoms the last two years. Chinese chestnut tree seems to die back ever winter and come back in summer from root stock. Same thing happened to the mulberry tree I planted last year. Of several evergreens I've planted along back fence in an attempt to block the sprayed poisons used by my sui/insecti/fungi/cidal neighbors, only one pine has survived. I think it's likely a watering problem. I just don't get out enough in the winter to pee on the trees back there... . The asian pear tree also provided us a bumper crop this year. Still a couple bowls of asian pears in the kitchen which we had to pick a little early due to the freeze we had last week. Both grape vines fruited moderately. Need more trellis for them to spread more.

Nectarine and sour cherry tree were both wiped out by fireblight this year. Since I've adopted a low sugar diet, I'm thinking about planting a nut tree of some kind, perhaps walnut. Next spring. May give Chinese apricot another try as well after I figure out how to cleanse fireblight.

Was not able to catch a bee swarm this year or last. But at least I've seen some honeybees buzzing the mint and oregano. I have two empty top bar hives.

Inside

I am going to try my hand at indoor BSF again this winter, should get the larvae by the end of this week I hope (don't know if they'll survive the trip otherwise). Meal worms are still going strong, but it's a manual process getting them to the fish tank. The BSF should do better self harvesting if I can keep them fed enough.

I'm also building a duckweed corral to provide a timed release of duckweed to the fish, while preventing them from overgrazing it. The tilapia are getting big on the meal worms and left over rice I throw in once a week or so. They're probably pretty confident in their survival as I remain quite averse to the labor of fish cleaning. It's probably been at least a year since I last ate any. Once my daughter is old enough to wield a fillet knife, they should worry though. There are a couple of tilapia fry in the sump, so I'm sure there's still at least one female in the main FT. There are one or two crawdads in the sump as well, so those fry will need to watch themselves. The last time I discovered fry (about 4 years ago), I managed to grow one out big enough to put into the main FT.

The grow bed still has cabbage, some kale and chives. I tried transplanting 3 of 4 tomato plants to the garden. One survived, but never got any fruit. The one still in the grown bed is looking straggly and also gave no fruit. This is about the 3rd time I've failed with tomatoes, so I think I'll leave any future tomato husbandry to my wife. What I'm excited about is that I have three mangroves sprouting. Hello brine shrimp -ponics (asfter I finish a couple more projects and grow out those mangroves a bit.

Finally fixed my controller system and installed a couple of flow sensors and a camera. The best thing is the bluetooth hose timer that I can now use my smartphone to add water to the fish tank every week. I lose about 5 gal a week due to evaporation/transpiration, and had been filling a 5 gal bucket up to do the top off for the last 5 years. Tried the direct hose thing once. Flooded my basement (thankfully before I finished it) but I learned that lesson. Doing the bucket brigade, I still managed to leave the water running on far too many occasions while filling buckets, but at least that water went down the drain, and not on the floor. The hose timer is controlled with same software as the outdoor sprinkler system, and lets directly into my fishtank for a specified time on whatever schedule I like. It also measures the flow rate. The FT camera is conveniently positioned to observe.

I'm also starting a new closed minihab but playing with lung designs, to vary the internal pressure on a daily basis to precipitate rain and create a tide. Aside from making it rain, this will give a chance to play with mass transfer of run off mineral sediments. I expect there'll be more on this later.

Under Pressure

Greg Vialle Monday 19 of August, 2019

Most closed ecosystem development can (and should be) done first on Earth to work out the kinks where there is a back up ecosphere. As I've started working again this week on the ecosystem simulator software my partner and I are commercially developing, I've been considering pressure threshholds and mixes. For structural and economic reasons, any terrestrial proto-CELSS is likely* to be maintained at close to atmospheric air pressure (standard temperature/pressure, STP, is 101 kPa at 23C), with essentially the same air mixture (78N₂/21O₂). Off Earth, this may not be the case. Below is a chart showing pressures and temperatures covering what is found on both Earth and on Mars, spanning the three phases of water we are most familiar with. The black box around STP covers acceptable limits of temperature and pressure for human habitability.

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For most of the space age, there have been two schools of thought on cabin pressure.

International Space Station (ISS)

The ISS is maintained at close to standard pressure and gas mix, due to the fact that the Russians designed Soyuz that way, and Soyuz is the life boat for ISS. Equalizing pressure takes time which may not be available in an emergency situation. This same logic applies when opening the Soyuz door on landing back on Earth at sea level. The US space shuttle was designed the same way for the same reasons. The relatively high pressure differential between the ISS cabin and the outside vacuum results in about a 5% loss per year leak rate. This is not a problem when you are just outside Earth's atmosphere and get resupplies at least 3 times per year.

Apollo

The Apollo program utilized a lower pressure of 30 kPa, using pure oxygen. This is possible because what is important (for the most part) is not the total pressure so much as the partial pressure of oxygen (shorthand "p(O₂)").
The 79kPA nitrogen (N₂) in air is metabollically inert. There are just as many dioxygen molecules in 21kPa of pure oxygen as there are in 101kPa of regular air. Combustion doesn't care, and neither do the lungs, for the most part. There are of course some subtle differences in heat convection and air movement that in the extreme affect a person's comfort in being able to productively cough, and probably would also affect the way a flame flickers. The thickness of the air also affects your sweat and how it feels when you are wet. Low vapor pressure means moisture evaporation (and its attendant cooling effect) happens more readily. My kids will certainly attest that summer swimming in high altitude (low pressure) Colorado (when it's 95°F) is colder than winter swimming in Florida (at 75°F). This effect will also apply to plant transpiration, but as plants are harder to survey, less research is available. So as far as we know, these human comfort considerations are what drive lower limits of total air pressure. This is why the pure O₂ in Apollo was at 30-35kPa and not at 21kPa.
The problem, as Apollo historians might guess, is that flammability increases with the p(O₂) level. At above 30kPa, even metal becomes flammable. Again, it's the p(O₂) that matters, not the total pressure, or the percent O₂. As the joke goes, how do you get an astronaut to bark like a dog? High p(O₂), one stray spark, and "woof!"

Suits
	Suit pressures have another consideration. Suits have to articulate joints to enable astronauts to move their limbs. Suits are big balloons. The greater the pressure difference between inside and outside, the harder it is to articulate. So suits are generally kept at lower pressure than spacecraft cabin pressure. Modern EVA suits are at about 30-40kPA (with p(O₂) of 21kPA, balance mostly N₂). Apollo PLSS suits were at pretty close to 25kPA, pure O₂. Discomfort of breathing thin air has to be balanced by discomfort of stiff joints. Mechanical counterpressure is one partial solution, but it is unfortunately not quite as trivial a solution as just wearing spandex. Incidentally, with an oxygen mask, the lower limit of human tolerable pressure is still at least 6kPA, which is still an order of magnitude higher than Martian air pressure. Below this pressure (known as the Armstrong Limit), water boils off the skin.

Talking habitat pressure outside of LEO, it makes sense to use lower total pressure (down to 32kPa), but probably not more than 22kPa of p(O₂). So you have to find a filler gas mix to make up about 10kPa. Some of that can be H2O, and some can be CO₂. But what are acceptable limits for H₂O and CO₂?

Carbon Dioxide (CO₂)

CO₂ is by far the simpler to consider. CO₂ levels in Earth's atmosphere are quite low (albeit, increasing): around 0.04 kPa. The reason for this is that plants are quite efficient at pulling it out of the air and sequestering the carbon. They can easily tolerate higher levels, and indeed grow faster at higher p(CO₂), but at the expense of veggie/fruit flavor and micronutrients. However, because they so efficiently convert the CO₂ to O₂, you can't just crank up the CO₂ knob without thinking about your crew barking. Humans by themselves cannot convert O₂ to CO₂ fast enough to produce sufficient food from just plants. There are three strategies you might use:

On Mars, you could pump in additional CO₂ from the weak atmosphere, then vent the excess O₂ bearing air, but you'll be losing water and whatever filler gas as well, so your various mechanical ISRU generators will be busy just maintaining your atmosphere. This strategy probably won't work so well on the Moon, where there is no atmosphere, and carbon (the C in CO₂) is in short supply.
You could also use combustion (of dried plant waste hydrocarbons) to help turn excess O₂ back into CO₂ and H₂O. As long as you keep the p(O₂) below 23 kPA (and take standard fire safety precautions), this is not as dangerous as it might sound. However, you will be releasing particulates and other volatiles into the atmosphere which will burden your filter system and/or lungs. On frigid Mars and beyond, combustion would have the advantage of producing heat, for both warmth and for cooking.
You could balance the plant mass with animal mass. The animals will offset plant O₂ production by converting it back into O₂ they'll also provide an additional food source (for crew), and method of recycling inedible plant wastes. You will have to take basic hygiene measures to prevent these animals from becoming disease vectors, and from destroying plants needed for human consumption.

Most likely, it will need to be some combination of these, depending on what the local resources are. The third option is clearly the most sustainable (i.e., requiring least resupply from Earth). Notice there is no mention of CO2 scrubbers. With plants in your system, you won't need CO2 scrubbers. While there is little research on the topic, metabolic studies suggest humans can tolerate CO2 levels a couple orders of magnitude higher, at least 1 kPa. On the other hand, astronaut Scott Kelly indicated that high levels of CO2 noticeably affected his moods during his record setting long duration stay on ISS (this was at STP and in null g).

One other thing to note with CO₂, is that it readily dissolves into liquid water, forming carbonic acid. It is estimated on Earth that about 1/3 of atmospheric CO₂ goes into the oceans this way. Since the surface area ratios and volume ratios will likely be different in a CELSS, it's unclear how much CO₂ would be absorbed by water, but it would probably not be trivial. As Biosphere 2 learned, Portland cement, too, will take up CO₂, sequestering not just the carbon, but the 2 oxygen atoms as well.

While my money is on a bioregenerative system for primary life support, NASA is working on a variety of approaches to manage CO₂. It is possible that one of these, or traditional scrubbers will be needed for backup.

Water (H₂O)

Obviously, water in liquid phase is required for both plant and animal life. Because of our sensitivity to it, water's unique physics, and the fact that Earth's temperature range spans the entire liquid phase of water, H₂O in the atmosphere is its own branch of science and engineering called psychrometrics. Atmospheric water vapor is commonly measured as relative humidity (%RH), which is a percentage of the condensation p(H₂O) for a given air temperature and pressure. Humans are most comfortable (at STP) in 40-60% RH. Most plants like a higher level: 80-90%RH. Electronics like a lower level: 40-50%RH.

These levels are equivalent to p(H₂O) of at most 5 kPa. That's for 100%RH at 35°C/95°F. Discussion of atmospheric water is incomplete without involving temperature. Internal habitat temperatures are likely to vary significantly, unless the entire CELSS is located somewhere deep underground (thermal stability is one reason you might do that, but also for radiation shielding). Even so, there is likely to be a nice thermal gradient between your power source and heat sink/radiator. For average air temperatures in the comfort regions (10°C to 35°C), there will necessarily be surfaces within the CELSS that are hotter or colder. Water vapor really likes to condense on colder surfaces. You can expect that, for a Martian hab, the walls separating you from the -70°C outside will probably be colder than the ambient air. On the Moon, that will only be true at night (which lasts 14 Earth days). A smart hab designer will incorporate this into the system, as part of the hydrologic cycle. I'll perhaps go into some of my experiments with this in a later post.

Filler gas (Ar, He, N₂)

If you were keeping track of the numbers, you'll have noted that humidity can account for no more than 5 kPa and CO₂ at best 1 kPa of the 10 kPa adddional pressure you'll need for habitat comfort. You'll need at least another 4 kPa of filler gas, probably a bit more so you won't be at 100%RH everywhere in the hab. The filler gas mix you use will depend on what is available/economical. In some cases, it may actually be the most expensive component of your atmosphere.

And no, wise guy, methane won't cut it.

On Mars at least, nitrogen (N₂) will be in short supply, so you'll probably want to use another inert gas like argon (Ar) or helium (He). Helium on the Moon and on Mars will be a natural byproduct of mining helium 3 for fusion power fuel. Yes, future Martians may indeed sound like animated Disney mice.

'*There is a case for conducting CELSS development on a mountain at very high elevation (>17000ft/5km) for this reason.

The Great Spiral

Greg Vialle Sunday 18 of August, 2019

WARNING: IF YOU THOUGHT THE LAST POST WAS TOO PHILOSPOHICAL, TURN BACK NOW.

The Great Filter provides a potentially useful analysis of where the dangers might lie for the advancement of life. The flaw in the analysis is that it presumes a linear history which makes our current situation a singular data point. If one instead takes a recursive view of life's history, then our current situation can be represented by a class of similar situations that have occured throughout the evolution of life on our planet.

If that last paragraph sounded like a whole lot of gibberish, please bear with me whilst we unpack it: Recursion is the mathelogical term denoting that a set contains itself, and that set contains itself, and so on, ad infinitum. There, I'm sure that cleared it up for you.

Now it's time for a little story about some critters called the UC_Ns.

The UC_N had arrived in the N-world virgin frontier in search of the bountiful resources there. As they came across resources, they autotrophically used the ambient energy sources to convert the matter into more UC_N, and the UC_N population grew exponentially. After many generations, the UC_N had long forgotten where they had even come from, and were coming upon limits of the frontier resources. Seeing the resource limitations, they began to compete amongst themselves. Some even began to prey upon the weaker UC_N to take their resources, and an arms race ensued, causing a divergence of heritable traits, where some of the UC_N became more efficient at processing raw resources, protecting them, and replicating, while the predatory UC_N became more invested and better at finding weak UC_N and taking their resources. As the generations progressed, different strategies for both the heterotrophs (predators) and the autotrophs evolved, resulting in a wide variety of both the autotrophs and the heterotrophs spanning all the various ecological niches of N-world, an entire hierarchy of predation, parasitism, and interdependence- in other words, the N-world had become an ecosystem.

Over time, the ecosystem itself changed, as the arms race raged, and as strategies, species, and resource accumulations rose and fell, rose again and fell again, over and over. Occasionally, a cataclysmic energy perturbation from outside N-world would upset the fragile ecosystem within the N-world, and reset the whole chain almost back to the very beginning. Eventually, a promethean UC_N looked beyond the boundaries of N-world and wondered what it would take to go beyond the edge of N-world. Many had tried and died, because they were not evolved for that hostile foreign environment. But what if they could take all the necessary dependent elements of their ecosystem and encapsulate them, then take this tiny bubble of N-world out into the great beyond to find other worlds there? So after building such a UC_N+1 bubble, they did. These bubble communities were deployed. They indeed discovered many worlds similar to the N-world, as well as vast resources between worlds. This greater aggregate world, the N+1-world, became a new virgin frontier and the UC_N+1 bubbles replicated exponentially as they found and converted the bountiful resources there.

And N was incremented.

The UC_N had arrived in the N-world virgin frontier in search of the bountiful resources there...

To those that have been following the idea of CELSS, the theme here is probably pretty transparent: the UC_N could be RNA, prokaryrotes, eukaryotes, or amniotes (which would be us). The standard ecological growth curve looks something like the beginning curve in the lower right graph:

SpiralGrowth

This is normally shown for a given species. In this case it represents the base autotroph (UC) of the N ecosystem (which is the encapsulated N-1 ecosystem). Typically, the exponential growth curve for the population of a species is followed by a precipitous population collapse, naturally occuring when resources are overexploited, or the population becomes diseased (i.e., it becomes overcome by inadequate regulation of the N-1 lower organisms). These two mechanisms are the most common cause of filtering (i.e. population bottlenecks), but there are of course external factors as well: maybe the sea vent or tidal pool dries up, or an asteroid hits. These external filtering events can happen anytime, regardless of habitat limits or population size.

Certainly, some habitats are more stable than others and some populations less fragile, but ultimately these filters are all statistical. It's less clear that making the encapsulation jump to exploit the N+1 next higher level world is so statistical. Perhaps it is just not as well understood by us, because it occurs on such a short geological timescale, or because it just so happens to be the next step for Earth life. The beautiful thing about cycles is that they can be replotted from cartesian time to a polar period chart. Doing that gives us something like this:

The Great Spiral. Each radial line represents a filter/gate. The bottom/right half of each cycle is typically where collapses (natural extinctions) occur. External extinction events can occur at any point in cycle.

This allows us to align the common stages in Life's progression. While it's still just a handful of datapoints, it's better than just one. It allows us to compare the differences between what we know of the different N levels, and systematically assess the odds of each filter (where the spiral crosses either a radial line or an N ring). Before moving on, it's worth noting that this formulation is a work in progress, and the left side of the chart could be done in a different order (e.g., encapsulation could occur before regulation).

What almost immediately stands out is that some steps are not quite like the others. The story of going multicellular is not quite the same as the standard UC story version above. And going from the ocean to land doesn't seem like quite a full step either. That's ok. It might be tempting to think that if these half steps were easier barriers to overcome, it makes them easy to rule out as Great Filters. But what if it's the opposite, those easy steps enabled us to surmount the odds to get to where we are (faster than other life on other planets)? After all, worlds of partial ocean (like Earth) are probably more rare than either dry worlds (like Mars) or completely wet worlds (like Europa). The barrier to go from water to air certainly seems like it would be more difficult to overcome than having an intermediate step of land.

The other thing made apparent by this analysis is that there are a lot of filters involved in evolution at every level. We like to think of evolution as leading directly and linearly toward ourselves. It didn't happen that way. There were millions of dead ends enroute, and there's no guarantee that we ourselves aren't a dead end. Yes, there was a lot of luck in getting to where we are: an ecosystem in spitting distance of having the capability of encapsulating replicas of itself and sending them into the solar system. But given a long time, statistically maybe it's not so much luck, as inevitability. After all, it did take 4 billion years for us. We should expect similar time periods for the aliens. The universe is only 13 billion years old. What if the conditions for life just weren't ripe until 5 billion years ago or so?

My guess is the aliens are out there; they just aren't much farther along than we are. Best not to drag our feet. Ultimately, we'll probably need each other, if we want to get to the N+2 ring.

The Great Filter

Greg Vialle Thursday 08 of August, 2019

WARNING: THIS POST WAXES INTENSELY PHILOSOPHICAL. Except when it is waxing biological. Read at your own peril.

The Fermi Paradox ponders the question of why we've yet to observe any sign of intelligent alien civilization. Speculative theories to explain the Fermi Paradox abound, including the Zoo hypothesis, UFO Conspiracy, Transcendence, Simulated Reality, and many other speculations closer to religion than to practical science. The Great Filter is so far the most useful hypothesis addressing the Fermi Paradox. It takes a process approach to analyzing the problem, positing that an advanced civilization must go through an evolutionary sequence of achievements to culminate at Kardashev level 2 or higher galactic colonization which would be observable even to an intelligent planet bound species such as our own. To explain the observed deficit of galactic society, at least one of these steps must pose a difficult if not impossible barrier to pass. The architect of this logic, Robin Hanson, defined the steps thus (my graphics and captions):

GreatFilter

Now if the impossible barrier is truly impossible, it must be the last step (else we wouldn't exist). This is the Copernican perspective which says not only are we not the center of the universe, we are just like every other doomed wannabe civilization on a bazillion planets across the universe.

Alternatively, the Rare Earth hypothesis much more optimistically says no, the hard part is the astronomically (literal) improbable odds of life originating, but because the universe is so big it had to happen somewhere, and we won the cosmic lottery so the universe is now ours to colonize.

There is also the admittedly circular Anthropic Priniciple, which says we are here because we are here and we observe what we observe because we are here.

There are a couple of exceptions I take to Prof Hanson's list. Foremost is the sexual reproduction step. From my understanding of Matt Ridley's "Red Queen*", sexual reproduction (i.e., gene recombination) is a natural consequence of cellular competition. Prof Hanson is to be forgiven however, as this line of thinking evolved after his original thesis. Hanson has also acknowledged that his list is likely incomplete. I'd agree- galactic conquest at #9 should really be number n, and be preceded by ellipsis. Beyond the obvious first step (develop CELSS and expand beyond Earth), we really don't know what steps to take. I also think there is a critical past step related to the formation of our moon, which is responsible for the magnetosphere, plate tectonics, and the carbon cycle governing much of the evolutionary path that took place on Earth.

This week we got hints of a breakthrough in microbiology where a possible relative of the missing link to eukaryotes was discovered. This is quite exciting because understanding how the seemingly unlikely symbiosis between two distinct domains of life occurred gives us hints about whether that was the Great Filter. Achaea and bacteria are genetically so distinct that some have speculated that one or the other may originate from elsewhere, with Mars being a likely candidate. Our own eukaryotic ancestors were the bastard hybrids of these original life forms. The more unlikely their chance meeting, the more likely that occurrence was the Great Filter. If we discover either archeans or bacteria on Mars, it would credit this theory and be great news for the future of our species. Jury's out if we discover both. If we discover eukaryotes, we're probably doomed. If we discover multicellular life that isn't eukaryotic the list will need to be rewritten (and it won't be good). If we discover nothing, things are looking up.

Looks like we gotta go to Mars. It's the next step in our continued survival anyway.

*Does it say something about me, that I gave a copy of "The Red Queen" to my wife on our very first date?

The Common Filter

Greg Vialle Tuesday 06 of August, 2019

Everyone learns about the hydrologic cycle in school. The following image will refresh you, if it's been awhile (or click on the wiki page link).

In the Earth's ecosphere, there is little emphasis on the transport of minerals carried by liquid water flow, because it's literally considered "a drop in the ocean". But in a CELSS, soil minerals leach out and end up in the water reservoir sumps, building up as water is evaporated back into the atmosphere. Not only does this brine sink have to be planned for, the "sea" might be a useful part of the ecosystem for growing algae and shrimp, as a staple food for aquaponics fish.

Soil bed reactors do act as quite sustainable filters to limit both erosion (loss of particulate minerals) and leaching (loss of soluble minerals), with the soil microbiotics and plants doing most of the the biological reintroduction of minerals, but ultimately water flows downhill, carrying some amount of its mineral load with it. At some point you'll need to collect these mineral deposits back out of the sump to reintroduce them into the various biological organisms in the ecosystem. Hence the common membrane filter (as opposed to the Great Filter, which I for one would like to avoid; more on this in a future post).

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In my aquaponics set up (as I imagine it is in most), one of the few manual tasks I have is cleaning pump filters (fish feeding is mostly automated except for occasional table scraps, or entertaining my 5 yr old daughter). I have tried vortex filters, but they are not that effective for the flow rates and space considerations for my small scale operation. So every month or so I have to consecutively turn off each pump, reach down into the turbid water of my sump, pull out the pump, open it up, remove the filter, clean the filter, reassemble, return to sump, switch on, and repeat for the next pump. It's not that frequent, and really not that onerous. With a better setup it might only need to be done twice a year. The filters are foam and normally outlast the pumps, usually because I'm not staying on top of my most frequent manual tasks of topping off the water, which in Denver's dry climate evaporates out of my system at a rate of about 1/3 gal/day. I've not gotten around to automating the refill process yet, mostly because overflow contingency is not existent (no drains), and the system is in my basement.

Anyhow, the filters are essential to my aquaponics system; and were I better at maintaining water level and pump integrity, the filters would eventually need replacing. Hence the common particulate filter.

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So that's two kinds of common filter, but how do you make such a filter? Glad you asked.

Yesterday I ran across this article about filters made of wood. This is a form of membrane filter. Pore size and hydrophylia are what control the size of contaminants excluded. Looking at the method of making these wood filters, I think there are oportunities to make a simplified version without the hydrophobic silane coating that would work as a particulate filter, without necessarily barring solutes. Either way, there is a vacuum freeze drying step. Very much doable if you've been growing some trees in your hab and happen to have an airlock with vacuum outside.

To accomplish the silane coatings you'd need a CVD setup. Which you also might have if you read my last post.

Vacuum Industries

Greg Vialle Sunday 28 of July, 2019

As an aerospace materials engineer, it's taken me a surprisingly long time to realize that the most useful property of space is not microgravity; it's the vacuum.

There are a number of modern testing processes that rely on vacuum or near vacuum.

Testing materials, I've frequently seen vacuum chambers used in electron microscopes (SEM and TEM) and for various high precision spectroscopy methods (where air can get in the way). Also, x-ray generating tubes are in vacuum. These devices are all notably expensive and are very limited in chamber size (a few inches in diameter).

At the bottom of Earth's N2/O2 atmosphere where humanity currently resides, creating a vacuum requires a pressure chamber with a door, and (usually at least two stage) pump system. If this sounds like an air lock, that's because it very much is. Guess where the best place for a materials lab is on your spaceship/station?

It also means that a lot of test equipment that, currently on Earth, is quite large due to pumps and cryogenics, can be made into handheld portable devices for specific use in a vacuum environment (whether by a suited human or by robot). Such materials testing devices are key to

prospecting (finding desired materials)

beneficiation (separating raw materials)

manufacturing (quality checking)

engineering (failure analysis)

basic science (material characterization)

In aerospace, we routinely use large vacuum chambers to vet space hardware prior to launch. Of course when you are doing the manufacturing in space, this step becomes trivial.

Speaking of manufacturing, perhaps the most lucrative use of vacuum lies in the various chemical vapor deposition (CVD) techniques that grow thin uniform layers. This is predominantly how silicon wafers are doped for use in microchips and how transparent conductive films are applied ubiquitously to touchscreens and photovoltaics. Many nanotech fab methods currently rely on CVD, including carbon in its various rare forms (bulk graphene, diamond, nanotubes). In space electronics, parylene film is routinely applied to printed circuit assemblies via CVD as a hard thin insulation layer to prevent tin whiskers from shorting circuits. Metal (Fe, Mo, W, Ni) carbonyl methods have previously been proposed for space manufacturing, as they logically follow from a particularly efficient extraction and storage method.

So imagine, if you will, the ability to manufacture space tethers of continuous strands of nanotubes grown uninhibited by vacuum chamber walls. Imagine a giant x-ray gun big enough to scan an asteroid, and imagine a swarm of spectrocopic sensors to identify and map the fluorescing elements within. Imagine graphene-steel composites for making ultralightweight solar sails and pressure chambers impervious to hydrogen permeation.

But wait! There's more... . Remember astronaut ice cream? Lyophilization, otherwise known as freeze drying, is a niche market on Earth due to the expense of vacuum chambers required to sublimate frozen water out of food. At the New Worlds conference a few years ago, someone asked my panel what the kitchens on Mars would look like. My response was that I thought pressure cookers would be used a lot due their efficiency, compactness, and safety. However I think now, especially that water is known to be quite abundant on Mars, there is an argument to be made for putting food out the airlock for preservation and storage. While standard freeze drying by itself is generally considered insufficient to kill microorganisms, I suspect that irradiation would do the job. Imagine the cuisine to arise from this method: perhaps lapin (rabbit) tartare, kale-tilapia pemmican, and various flavor infusion reconstitutions.

While the vacuum industry will certainly help to open up space development technologically, the products will also enhance life on Earth, and provide the capital incentives to get this new vacuum industry off the ground. Literally.

Transformed by Fungi

Greg Vialle Tuesday 21 of May, 2019

Until I was in my mid-30s, I despised mushrooms. This was around the time I met my wife, so she likes to take credit for the transformation, but my recollection is that it was a gradual transition from associating mushrooms with sliminess to a more favorable association to the nutty flavor and earthy scent of truffles. Perhaps it is an instinctual thing that protects children from eating poisonous toadstools that wore off. Indeed, two of my children seem to have found my lost disgust.

Even though I'd gained a culinary appreciation for the fungal kingdom, in the intervening decade or more that CELSS technology has been my active interest, my focus has been on the symbiosis of the plant and animal kingdoms. Until recently. A month ago I started a mushroom grow kit I received as a gift, and expanded my practical experience beyond aquaponic gardening and small animal husbandry. I have also some white truffle spores I intend to sow next.

A couple weeks ago as my mushrooms began to emerge, I was looking for something educational to watch while exercising and ran across The Kingdom: How Fungi Made Our World which got me thinking not just about the practicality, but the necessity of fungus, especially in the ab initio creation of a stable ecosystem.

These thoughts on the biochemical mastery of the fungus kingdom have been "fermenting" in the back of my head these past weeks. Then today I ran across a couple of news items that have prompted the writing of this post:

One Billion Year Old Fungi Found is Earth's Oldest

NASA Soon to Launch Biosentinels

It now seems clear to me that primitive mycorrhyzal fungi and lichen may need to be seeded even before plants in a habitat, as they can best break down raw minerals into the constituents of life.

Counter Mono Rules

Greg Vialle Monday 22 of May, 2017

Like economies, unregulated ecosystems have a tendency to compete towards a single species monopolizing the system. Paul has mentioned this in his blog posts as “going monoculture”. Here are a couple of "rules of thumb" I've been pondering of late.

RULE#1

If multiple species are competing in the same ecological niche, one will always outcompete the others, and take over… unless there is a check to keep the diversity in balance. One way to diversify the overall ecology is to differentiate areas of the habitat to provide local advantage to different species.

RULE#1: Ecological stability is proportional to habitat diversity.*

Habitat diversity can also be a means to provide the sanctuary discussed in Rule#2. This is why it's good to have both aquatic and a terrestrial biomes in the habitat. There are other reasons for having both as well, but this serves to prevent a single species from taking over both biomes. Having a soil based terrestrial biome provides surface area and sanctuary for bacteria and other subterranean life. Having an aquatic biome provides a reservoir for the water in the system, in addition to providing thermal mass, and supporting a volumetrically efficient autotroph habitat. In other words it allows a lot of algae to remove minerals from the water and simultaneously produce oxygen.

Another approach might be to have different climates, where different species might have the local edge in resource competition. In addition, a thermal gradient provides an engine to transport water (hydrologic cycle). Habitat diversity is about gradients; gradients in accessibility/media, light, temperature, nutrients, and humidity.

*This may not be precise in a mathematical sense; indeed it's likely a sigmoidal response (as with most things in nature) rather than linear.

RULE#2

Typically going mono is exemplified by one species of plant overgrowing the habitat. If a species of herbivorous animals is introduced to check plant growth, they will soon decimate the plants, and eat themselves into a starvation induced extinction. The best way to prevent this is to introduce an apex predator, preferably an obligate carnivore. However, unless there are sanctuaries, the herbivores will end up decimated, and the predators will be in the starvation induced extinction position, leading ultimately back to scenario 1.

So this implies the second rule:

Rule #2:  The food chain must have an apex predator whose prey has some sanctuary.

Now I had mentioned that this apex predator be an obligate carnivore. There are a couple of possible exceptions.

The first is to use an herbivore or omnivore and instead provide sanctuary for the plants. An example of this might be to have grass growing up through a mesh that is impervious to the gnawing of grazers above. Another method might be to rotate grazing, as Paul discusses in one of his posts. That is less feasible when applied to populations, versus an individual animal.

So that's the first exception. The other one that has me musing, is to use humans. Of course we aren’t obligate carnivores, even on a ketogenic diet (as I currently am). So what checks are to keep us from consuming ourselves into a starvation induced extinction, in a closed habitat (such as, ahem, on Earth)?

•   Sanctuary? It is difficult to imagine a sanctuary for our food, devisable by humans that can’t be overcome by humans ingenuity.

•   Habitat rotation? Again, I suspect most schemes would be surmountable by human ingenuity

•   Rationality? Tragedy of the commons, hello.

•   Societal Rules? Maybe.

•   Robot Overlords? Well…

A third exception, devised by nature, is another form of predator that consumes its prey incrementally rather than by discrete individuals. Yep, I'm talking about parasites. The beauty of this solution is that such a species links both ends of the food chain making it a loop. However, I've never been a fan of having mosquitos (or ticks, tapeworms, vampire bats) included in my ideal habitat design. Given the choice between mosquitos and Robot Overlords, however… tough call. I'd really like to think we could make some Societal Rules workable.