Closed eco-systems

You raise some very important issues. You're right about previous
studies advocating changing the composition of the habitat's
atmosphere. They do this to lessen the structural load on the
habitat and to lessen the amount of gas that MAY have to be brought
from earth if a source can't be found in space.

I've had my reservations as to the wisdom of the reduced atmosphere
position but have been unwilling to defend a position because of the
scarcity of experimental data on the complexity of the new
environment and most importantly, I'm really out of my depth in this
field.

My concerns are that an eco-system is a very complex system. While a
closed new environment might be sustainable in a small test
environment over a limited test period of time, I'd be concerned
about scaling up to a habitat size and letting it run for the life
of the habitat. Further, my concerns would also extend to the
findings of the pilot-plant study being used in the design criteria
for the habitat, i.e. designing for a reduced atmospheric pressure.
It's hard to come up with a solution for an eco-system which may
destabilize when options become closed to you.

The example you raised furthers my apprehension. Perhaps a solution
is to design the first habitats for full atmospheric pressure,
despite the engineering challenge that would present, and replicate
the earth's eco-system as closely as possible. In a sense, we use
the first habitat's as living laboratories and develop a base-line
of experience before we embark on a design change which would impact
on the entire design of the habitat. I guess I see it as a question
of which technologies have we the most mastery of: engineering of
large structures or design of eco-systems. I'd vote for engineering
science being the most developed and with fewer component
interactions, and with most of the interactions being more fully
understood than what we'd find in the practice of eco-system design.

--- In spacesettlers@y..., "Serkan, Anilir" wrote:
> I would like to share your idea about the following topic...
>
> Concerning, the closed ecosystem of a habitation, the information I
> found is usually based on the idea that the percentage of nitrogen
is
> decreased and oxygen is increased (up to 70%), so it will weight
three
> times less than normal air and be cost-effective...
>
> According to my knowledge, The stabilization of the basic
ecosystem will
> require redundancy in its diverse systems. For example, often
> interaction between populations of organisms rank more important
for the
> stability of an ecosystem than the activity of single organisms. On
> Earth, an enzyme (nitrogenase) is responsible for taking
atmospheric
> nitrogen and changing it into high-energy ammonia (NH3). The
ammonia is
> necessary for protein production. The most important point here is
that
> oxygen must be kept away from away from nitrogenase. If we have
too much
> oxygen, there will be no production of ammonia and protein. It is
hard
> enough on Earth to keep Nitrogenase active without upping the
amount in
> the atmosphere to 80%. The nitrogen-fixing bacteria and trace
elements
> like molybdenum or crucial elements like phosphorus (creating the
> universal energy of all living organisms (ATP)) are necessary
elements
> for a sustainable closed ecosystem.
>
> so does anybody have some information or ideas about sustainable
closed