No moBananas

Hi,

>I'm not sure if you're making a statement of fact or asking a
>question.

Statement. The smaller an open system is, the more reliant it is on
external resources. The smaller a closed system is, the soon it will fail,
moreso if people are in it.

>First off what do you mean by a sustainable ecosystem?

a diverse self-maintaining open system with the ability to buffer against
fluctuations in the environment and adapt to changing conditions from
external sources.

A small closed system is not adequate for long-term survival. Not if humans
are included. Toxins build up, technology fails.

>Secondly, perhaps humans can live in a ecosystem that only meets
>their needs

Technological or survival?
Technological needs require an industrial complex, to produce spare parts
for maintenance. It consumes significant energy and material resources and
produces a lot of waste. There is only so much that can be recycled before
new resources are required.

Survival needs require a biodiverse ecosystem, capable of supporting human
needs and recycling human wastes, while stopping toxins from building up.
Diversity is essential to buffer against environmental changes. What if
people relied on a handful of species for food and those species died out?

Bananas are the perfect example.
Bananas are a main source of food for a fifth of the world's population .
Yet the banana is likely to be extinct in the next 20 years. Almost all
Bananas are grafted from a parent tree. They are rarely grown from standard
pollen-based sexual reproduction. Except for a few mutations they are
virtually clones, selectively bred to produce the largest bunches. The
species has no genetic diversity. Rust molds are currently decimating
banana crops in third-world countries. Because there is no genetic
diversity in the species, all the individual trees are susceptible and die.
It is only a matter of time before the rusts infect bananas in first-world
countries and the species dies out, except maybe in the wild where is
continues to reproduce by pollen.

How many other food species, that we rely on, are selectively breed for
only one trait? The juiciest watermelons, highest-yield wheat, largest cobs
of corn, crispiest apples, the fatest chickens, the leanest beef. Certainly
the changes are good for us but in doing so we reduce the genetic diversity
of those species, or worse, we force speciation. Speciation is where a
small group of one species is isolated and so pressured from external
sources that it forms a sub-species and later it's own species. This
disconnects the group from the genetic diversity in it's progenitor
species. Only through mass sexual reproduction, mutations and significant
die off does the group regain the genetic diversity needed for long-term
survival.

It's interesting to note: every human alive today is descended from one of
only five females. We have already undergone the stage of mass sexual
reproduction, our population grew exponentially. We're now reaching the
limit of our resources. Our use of nuclear energy and synthetic chemicals
are producing mutations at an alarming rate. It seems the next stage for us
is a significant die off. Assuming of course we don't expand to other
planets and form new sub-species there.

>Considering the population density we'll probably have, I'd compare it to the
>ecosystem needed to keep NYC going. Not much NEED for bee, birds, trees,
>lakes,
>rivers, savanah, etc.

NYC is the perfect example of an unsustainable ecosystem. It doesn't
produce it's own food and can't process it's own waste. It is totally
reliant on surrounding systems to survive.

The birds and the bees are needed for the pollination of our food species.
Without them our food will loose it's genetic diversity, or not grow at
all. Trees are needed to keep the water table down, provide breeding and
resting sites for the birds, and convert CO2 into O2. Lakes and rivers
(large bodies of water) are needed to buffer against temperature
fluctuations, and store water for the crops and provide drinking water for
birds, bees and people.

I have to say, a majority of city people just don't realise how dependant
they are on farms, and nature in general. Perhaps this is why there is so
much missunderstanding about the essential need of biodiversity in future
space settlements.

>I think the correct figure you meant to quote was 6 ft of dirt
>around the shell of smaller Habitats will approximate the radiation
>dosage equivalent to Denver. Can anybody else backstop me on this?

I've checked. It's 14 feet of concrete, a few feet of lead or a planetary
atmosphere. Apparently the rare-earth elements do a better job but they are
too rare to use in large scale structures.

>For the larger Habitats, usually the thickness of the pressure shell
>and the thickness of the atmosphere is sufficient protection.

How thick are you talking?

>I'm not sure how you mean that the thermal conditions of the
>atmosphere is prone to catastophic failure?

In a closed system temperatures can rise quickly, too quickly for
air-conditioning to extract the heat. Sudden temperature increases, such as
house fire, in a space settlement can have a major system-wide impact
whereas on a planet the impact is localised and the system as a whole
continues to function and recovers easily.

>Sometimes it takes a new way of looking at the problem to find the solution.

Solutions are what we need. Discussion is the best way to start.

Michael :]