Growing crops in orbital colonies

On 10/6/05, vijay kumar wrote:
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> i would like to know if it is possible to grow all the crops that we grow on earth in orbital colonies on a scale that is needed to support billions of people in the future in space habitats. i remember biosphere experiment proved a disaster and has there been any more such experiments.

There were other experiments with better results because they involved
less variables - usually just a few crops under tightly controlled
environmental conditions, without that Biosphere II ambition of "being
a second biosphere".

Another trap ambition where those experiments usually fall is to have
an artificial biosphere were everything gets recycled with 100%
efficiency. Well, guess what, it is IMPOSSIBLE to recycle everything
with 100% efficiency, even Earth itself does not have 100% efficiency
(though the fluctuations take so long to build up that it is difficult
to perceive them). Besides, it is not *necessary* to have a 100%
efficiency since space has raw materials that could replace substances
lost due to inefficiencies in the system.

> is it possible to convert the lunar soil and asteroid rocks into fertile soil to grow the crops > does the technology exist already?

Experiments with lunar soil samples in the 70s demonstrated that the
lunar soil seems to be naturally fertile for many plants due to its
basalt content (http://www.hort.purdue.edu/newcrop/proceedings1990/v1-532.html).
Of course you have to add water. The situation of asteroid soil is not
known and I suspect that the fertility of those rocks varies
enormously as there are various extremely different kinds of
asteroids.

> and also is there really any water in moon and near earth asteroids to use for growing crops, drinking water needs and industrial uses. if there is no sufficent water. what is the plan B? . should we manufacture the water or extract it from earth somehow?
(...)

We know from spectroscopy observation and direct analysis of
meteorites that there are types of asteroids that do contain water. As
for the prospect of water in the Moon, there is a lot of indirect
evidence saying that the poles seems to contain an undetermined amount
of water. Some people also think that it is possible to *manufacture*
water in the Moon by extracting oxygen from the silicates in the soil
and rocks and combining it with solar hydrogen trapped in metal
particles in the soil.