How should the CO2 be released into the Habitat? Once the basic
atmosphere is established there will need to be a constant release
of CO2 for a couple of decades. Should this be done from one central
exhaust pipe and count of circulation to disperse the gas? Of course
this would concentrate the gas to deadly levels at the pipe exit.

Perhaps multiple pipes? I tend to favor an exhaust pipe running high
up into the atmosphere where the deadly concentration won't affect
anyone and dispersal could be assured by wind generated from
coriolis forces. Of course we could also place an intake pipe there
to suck in the atmosphere so as to seperate out the O2 to combine
with the carbon.

Any ideas on this design issue?

TangoMan

I'm sorry but I'm not following... Why does CO2 need to be released
into the atmosphere? I can see it if the habitat is primarily
intended for agriculture but I was under the impression that CO2 was
currently filtered out.

Assuming CO2 does need to be released, what you say is probably a
good way to do it. That or maybe use an air pre-mixer.

Joe

--- In ssi_list@... "victoriatangoman"
> How should the CO2 be released into the Habitat? Once the basic
> atmosphere is established there will need to be a constant release
> of CO2 for a couple of decades. Should this be done from one
central
> exhaust pipe and count of circulation to disperse the gas? Of
course
> this would concentrate the gas to deadly levels at the pipe exit.
>
> Perhaps multiple pipes? I tend to favor an exhaust pipe running
high

--- In ssi_list@... "victoriatangoman"
> How should the CO2 be released into the Habitat?

By people breathing out is my first guess.

> Once the basic
> atmosphere is established there will need to be a constant release
> of CO2 for a couple of decades. Should this be done from one
central
> exhaust pipe and count of circulation to disperse the gas? Of
course
> this would concentrate the gas to deadly levels at the pipe exit.
>
> Perhaps multiple pipes? I tend to favor an exhaust pipe running
high

--- In ssi_list@... "isildurbane"
> I'm sorry but I'm not following... Why does CO2 need to be
released
> into the atmosphere? I can see it if the habitat is primarily
> intended for agriculture but I was under the impression that CO2
was
> currently filtered out.
>
> Assuming CO2 does need to be released, what you say is probably a
> good way to do it. That or maybe use an air pre-mixer.
>
> Joe

From the moment that the airlock is opened and the Habitat starts to
accept new residents there will be a period of a decade or two until
the biosphere reaches equilibrium. I'm assuming that there will be
vegation throughout the Habitat and the mass of the trees and bushes
comes entirely from the atmosphere. A tree massing 3 tonnes needs to
get that carbon from the atmosphere before it can be counted as part
of the equilibria of the biosphere.

Think of it this way - the hatch opens and there is a bare Habitat.
Lot's of O2 and N2 in the atmosphere, but bare ground everywhere.
You start breathing and eating and outgasing CO2. What's going to
process the CO2? Machinary, I'm sure. Now, do you invision a Habitat
completely bare of vegation? All concrete and steel with no trees,
grass, flowers, or bushes. If not, it's going to take a very long
time for people's exhalations to provide the Carbon for vegation to
grow. Further, where will the carbon in their diets come from? The
closed cycle will likely be sought after but we'll need to be
banking (sequestering) carbon to develop greenary in the Habitat and
this will disrupt the closed cycle.

TangoMan

--- In ssi_list@... "nini_net2000"
> --- In ssi_list@... "victoriatangoman"
> > How should the CO2 be released into the Habitat?
>
> By people breathing out is my first guess.

Where will the carbon that forms the CO2 in people's exhalations
come from? It doesn't spontaneously appear in your lungs.

TangoMan

--- In ssi_list@... "victoriatangoman"
> --- In ssi_list@... "nini_net2000"

> > --- In ssi_list@... "victoriatangoman"
> > > How should the CO2 be released into the Habitat?
> >
> > By people breathing out is my first guess.
>
> Where will the carbon that forms the CO2 in people's exhalations
> come from? It doesn't spontaneously appear in your lungs.
>

Is this a serious question ?

Living humans (and all animals) eat food and inhale oxygen.

They metabolize the food and oxygen together, and exhale CO2 and
water vapor. This process also generates heat which must be
disposed of somehow.

The amount of CO2, H2O and heat emitted varies with the amount of
physical exertion.

The food could be grown locally or imported.

--- In ssi_list@... "victoriatangoman"
>
> From the moment that the airlock is opened and the Habitat starts
to
> accept new residents there will be a period of a decade or two
until
> the biosphere reaches equilibrium. I'm assuming that there will be
> vegation throughout the Habitat and the mass of the trees and
bushes
> comes entirely from the atmosphere. A tree massing 3 tonnes needs
to
> get that carbon from the atmosphere before it can be counted as
part
> of the equilibria of the biosphere.
>

There's the difference. I was assuming that -at least at first- the
habitat would be bare of vegetation. Seeds would be imported into the
habitat over time but not full plants. Food would also have to be
imported at this time.

>
> TangoMan

Joe

--- In ssi_list@... "Charles F. Radley"
> --- In ssi_list@... "victoriatangoman"
> > --- In ssi_list@... "nini_net2000"
>
> > > --- In ssi_list@... "victoriatangoman"
> > > > How should the CO2 be released into the Habitat?
> > >
> > > By people breathing out is my first guess.
> >
> > Where will the carbon that forms the CO2 in people's exhalations
> > come from? It doesn't spontaneously appear in your lungs.
> >
> Is this a serious question ?

I posed the answer to get the poster to think about the carbon
*cycle.* The carbon must originate somewhere before it enters the
human metabolism to be exhaled as CO2.

The amount of carbon that is banked in biomatter in order to get to
the point of CO2-O2 photsynthetic equilibria is sufficiently great
as to necessitate feeding carbon into the cycle.

TangoMan

--- In ssi_list@... "isildurbane"
> --- In ssi_list@... "victoriatangoman"
> >
> > From the moment that the airlock is opened and the Habitat
starts
> to
> > accept new residents there will be a period of a decade or two
> until
> > the biosphere reaches equilibrium. I'm assuming that there will
be
> > vegation throughout the Habitat and the mass of the trees and
> bushes
> > comes entirely from the atmosphere. A tree massing 3 tonnes
needs
> to
> > get that carbon from the atmosphere before it can be counted as
> part
> > of the equilibria of the biosphere.
> >
> There's the difference. I was assuming that -at least at first-
the
> habitat would be bare of vegetation. Seeds would be imported into
the
> habitat over time but not full plants. Food would also have to be
> imported at this time.

I'll go with your assumption. We start with seeds. You eat some
astronaut food prepared on Earth. You enter the hatch of the newly
opened Habitat and breath pure air derived from the gases of
asteroids. It takes a while for some CO2 from settler's exhalations
to build up in the atmosphere considering the volumes involved.

The photosynthetic process looks like this:

6CO2 + 6H20 + Light ---> 6O2 + C6H12O6 (carbohydrates)

The carbohydrates are what biomatter consists of. So your breath
exhalations provide the *mass* for the plants.

A human's contribution looks like this:

O2 + carbohydrates ---> CO2 + H2O + energy

When you are in a closed equilibria, you would consume your
carbohydrates consisting of plant and animal matter and your
exhalations would provide the source materials to create new
carbohydrates elsewhere in the biosphere.

You'll note that the closed equilibria requires existing plant
biomatter to act as the engine of transformation. So, starting with
your seeds they will consume your exhalations, release the O2 and
bank the carbohydrates to allow them to grow. You now need a source
of carbohydrates for your food. Where does that come from? Are you
going to harvest the fledgling seeds and consume them?

Pick a population size for your Habitat. 10,000? 100,000? 1,000,000?

To make the calculations simple, let's say 10,000 new settlers come
into the Habitat all at once (steady state rather than a growing
series.)

Each person consume 53 liters of O2 per hour.

Plankton seems to be one of the most efficient mechanisms for
photosynthesis per unit mass, but I'm assuming you want to live in
more than one large orbiting plankton tank so I'm going to assume
plankton away for this illustration.

Here is some data from the BioSphere 2 facility:
http://www.ldeo.columbia.edu/edu/dees/ees/climate/labs/photo/

Here is the math for how to calculate photosythetic rate per unit
area of leaf:
http://www.water.hut.fi/wr/kurssit/Yhd-12.135/kirja/photos.htm

Here is data for Leaf Photosynthesis Rates:
http://www-
eosdis.ornl.gov/FIFE/Datasets/Vegetation/Leaf_Photosynthesis_Rates.ht
ml

Here is a model for Leaf Area Index for Forests:
http://www.nrel.colostate.edu/projects/century5/reference/html/Centur
y/submodel-forest.htm

Here is a paper on the relationship between tree height and leaf
area:
http://www.fsl.orst.edu/~bond/PDF%20files%20of%20papers/McDowell%
20Oecologia%202002.pdf

Here is some data on the proportion of leaf biomass to total tree
biomass, ranging from 3%-20%:
http://www.ias.ac.in/currsci/dec25/articles30.htm

Here is more on the relationship between leaf area and leaf mass:
http://soil-physics.nmsu.edu/sp/research/posters/sla_98/sla1.pdfNow

Here are the densities of some different woods. Think about how much
carbon and hydrogen they've had to pull into the tree to grow that
mass:
http://www.simetric.co.uk/si_wood.htm

Now this question really has the potential to get bogged down in
specifics, so to avoid that outcome I'm going to use this rough
estimation:
http://www.newton.dep.anl.gov/newton/askasci/1993/biology/bio027.htm

350 small plants will produce enough O2 to supply a human. If their
leaf biomass is 10% of their total biomass, then you're going to run
down your initial carbon stocks as they are deployed to trunk, root
and branch biomass development which all support the leaf biomass
which in turn produces the O2.

So, in your newly opened Habitat with 100,000 people they'll be
exhaling 53 liter/hour of CO2 * 100,000 * 24 hrs = 127,000,000
liters/day. They'll need 3,500,000 *grown* plants to achieve
equilibria.

Your initial carbon and hydrogen stocks are getting depleted as your
biomass is growing. That's why I think we'll need to be adding to
the stocks until the biomass reaches a point of stability where we
can harvest food, eat it, exhale the gases, which in turn are
processed by the biomass back into O2 and food.

TangoMan

--- In ssi_list@... "victoriatangoman"
>
> I'll go with your assumption. We start with seeds. You eat some
> astronaut food prepared on Earth. You enter the hatch of the newly
> opened Habitat and breath pure air derived from the gases of
> asteroids. It takes a while for some CO2 from settler's exhalations
> to build up in the atmosphere considering the volumes involved.
>

I was thinking more on the scale of the ISS. The volume isn't as much
there...

> The photosynthetic process looks like this:
>
> 6CO2 + 6H20 + Light ---> 6O2 + C6H12O6 (carbohydrates)
>
> The carbohydrates are what biomatter consists of. So your breath
> exhalations provide the *mass* for the plants.
>
> A human's contribution looks like this:
>
> O2 + carbohydrates ---> CO2 + H2O + energy
>
> When you are in a closed equilibria, you would consume your
> carbohydrates consisting of plant and animal matter and your
> exhalations would provide the source materials to create new
> carbohydrates elsewhere in the biosphere.
>

I wasn't assuming a closed equilibrium.

> You'll note that the closed equilibria requires existing plant
> biomatter to act as the engine of transformation. So, starting with
> your seeds they will consume your exhalations, release the O2 and
> bank the carbohydrates to allow them to grow. You now need a source
> of carbohydrates for your food. Where does that come from? Are you
> going to harvest the fledgling seeds and consume them?
>

No. I was going to import the food until the plants are ready. (And
probably some afterwards.)

> Pick a population size for your Habitat. 10,000? 100,000? 1,000,000?
>

10-100. You think big. :) (Yes I know that was the scale O'Neill
proposed.)

> To make the calculations simple, let's say 10,000 new settlers come
> into the Habitat all at once (steady state rather than a growing
> series.)
>
> Each person consume 53 liters of O2 per hour.
>

I've always assumed the O2 the people require would be recycled by
mechanical/chemical means such as sabatier reduction.
CO2 + 4H2 -------> CH4 + 2H2O
The methane could be burned in the growing areas to supply the plants
with CO2. While the water would be reduced to recycle the hydrogen
and provide oxygen for the people.

http://advlifesupport.jsc.nasa.gov/../documents/simaDocs/MSAD-00-
0292.pdf

> Plankton seems to be one of the most efficient mechanisms for
> photosynthesis per unit mass, but I'm assuming you want to live in
> more than one large orbiting plankton tank so I'm going to assume
> plankton away for this illustration.
>
> Here is some data from the BioSphere 2 facility:
> http://www.ldeo.columbia.edu/edu/dees/ees/climate/labs/photo/
>
> Here is the math for how to calculate photosythetic rate per unit
> area of leaf:
> http://www.water.hut.fi/wr/kurssit/Yhd-12.135/kirja/photos.htm
>
> Here is data for Leaf Photosynthesis Rates:
> http://www-
>
eosdis.ornl.gov/FIFE/Datasets/Vegetation/Leaf_Photosynthesis_Rates.ht
> ml
>
> Here is a model for Leaf Area Index for Forests:
>
http://www.nrel.colostate.edu/projects/century5/reference/html/Centur
> y/submodel-forest.htm
>
> Here is a paper on the relationship between tree height and leaf
> area:
> http://www.fsl.orst.edu/~bond/PDF%20files%20of%20papers/McDowell%
> 20Oecologia%202002.pdf
>
> Here is some data on the proportion of leaf biomass to total tree
> biomass, ranging from 3%-20%:
> http://www.ias.ac.in/currsci/dec25/articles30.htm
>
> Here is more on the relationship between leaf area and leaf mass:
> http://soil-physics.nmsu.edu/sp/research/posters/sla_98/sla1.pdfNow
>
> Here are the densities of some different woods. Think about how
much
> carbon and hydrogen they've had to pull into the tree to grow that
> mass:
> http://www.simetric.co.uk/si_wood.htm
>
> Now this question really has the potential to get bogged down in
> specifics, so to avoid that outcome I'm going to use this rough
> estimation:
> http://www.newton.dep.anl.gov/newton/askasci/1993/biology/bio027.htm
>

I was looking for this info a while back for another group.
Thanks!

> 350 small plants will produce enough O2 to supply a human. If their
> leaf biomass is 10% of their total biomass, then you're going to
run
> down your initial carbon stocks as they are deployed to trunk, root
> and branch biomass development which all support the leaf biomass
> which in turn produces the O2.
>
> So, in your newly opened Habitat with 100,000 people they'll be
> exhaling 53 liter/hour of CO2 * 100,000 * 24 hrs = 127,000,000
> liters/day. They'll need 3,500,000 *grown* plants to achieve
> equilibria.
>

Is the balance the same if you're just looking to grow food?

> Your initial carbon and hydrogen stocks are getting depleted as
your
> biomass is growing. That's why I think we'll need to be adding to
> the stocks until the biomass reaches a point of stability where we
> can harvest food, eat it, exhale the gases, which in turn are
> processed by the biomass back into O2 and food.
>
> TangoMan

Btw, I do see your point.

Joe

--- In ssi_list@... "isildurbane"

> No. I was going to import the food until the plants are ready.
(And
> probably some afterwards.)
>
> > Pick a population size for your Habitat. 10,000? 100,000?
1,000,000?
> >

Here are the REGENERATIVE LIFE SUPPORT - INPUTS AND OUTPUTS for ISS.
http://oregonstate.edu/~atwaterj/io.htm

Pick your parameters and figure out the launch cost to supply.

> I've always assumed the O2 the people require would be recycled by
> mechanical/chemical means such as sabatier reduction.
> CO2 + 4H2 -------> CH4 + 2H2O
> The methane could be burned in the growing areas to supply the
plants
> with CO2. While the water would be reduced to recycle the hydrogen
> and provide oxygen for the people.

I think mechanical means will also be used with the increasing load
of increasing population, over time, being taken up by the growing
biosphere.

However, even with mechanical means, we're still left looking for
the carbohydrate stream for plant growth.

> I was looking for this info a while back for another
group.
> Thanks!
>

Glad to help.

> Is the balance the same if you're just looking to grow food?

If all you want is food then I'd guess you simply calculate the mass
of the food intake, the plant waste from the food, and then you'll
have a rough idea of how much carbon and hydrogen you need to bring
into the biosphere apart from the need for carbon scrubbing. You'll
also need to calculate the cycle time for the food to grow. So 1 kg
of food per day, half of it being waste, and 60 days of cycle time
means you need to import 120 kg of carbon and hyrdrogen per person
for their food cycle alone. A 10,000 person settlement means 1,200
tonnes. Just choosing a rocket at random

http://astronautix.com/lvs/pro86101.htm

you're looking at over 600 launches to get your material beyond GEO.
At $70 million (or whatever) per launch you're looking at some
serious money.

I know there are some biologists who subscribe to this list, perhaps
they could weigh in with expert knowledge.

TangoMan