Growing crops in orbital colonies

> It just seems that those of us thinking about permanent human
> colonies in orbit should look beyond these systems to something
> that is self-sustaining and undemanding of resources--composting,
> topsoil, and otherwise replicating earth-side agriculture as
> precisely as we can.

Spacefaring societies should use whatever means of carbon recovery
and food production is most efficient, and I don't see any way of
deducing from first principles which that will be. It may turn out
to be hydroponics. It may turn out to be nearly abiotic artificial
soil. It may turn out to be living soil with closely managed
ecosystems that differ sharply from what now exists essentially in
the wild on our farms. It may turn out to be replicating earthside
agriculture fairly closely.

Or at the other extreme, it may not use plants at all: maybe the CO2
will be concentrated by adsorption/desorption cycles, separated into
carbon and oxygen by a modified Bosch process, converted chemically
into small molecules like ethanol, and fed to bacteria to produce
people-food.

Hydroponics and zeolites have an advantage over living soils for the
types of preliminary evaluation that NASA has done: if all you're
growing is the plants, you can get some information from growing a
crop and making some fairly simple measurements; otoh, if you're
growing a whole ecosystem of fungi, bacteria, soil algae,
protozoans, nematodes, annelids, insects, and whatever else, you
have to culture the soil itself, and you have a huge number of
parameters to control and measure.

--- In spacesettlers@yahoogroups.com, "Brad Walsh"
>
> >I am very interested in this and would like your impute and
references to
> >where to find more information on the plants desirable.
>
> Well I can't find it now, but awhile back I saw a webpage listing
current
> and recent grant-funded space agriculture projects sponsored by
NASA Ames.
> It included soil-substitute and hydroponics research, and research
on
> various food crops.
>
> This NASA progress report from 2003:
> http://advlifesupport.jsc.nasa.gov/documents/CropDocs/TM-2003-
211184.pdf
> shows about where we are, in gratifying detail.
>
> The document talks about hydroponics somewhat, but doesn't mention
zeolites
> (one of the types of artificial soils being researched for future
space
> applications). To me it is significant that both hydroponics and
zeolites
> are resource-intensive growth media, and the efficiency of
zeolites goes
> down hill rapidly after several crop generations. That means that
while
> they would be OK for multi-year missions like the trip to Mars,
they'd be
> less desireable for much longer. It just seems that those of us
thinking
> about permanent human colonies in orbit should look beyond these
systems to
> something that is self-sustaining and undemanding of resources--
composting,
> topsoil, and otherwise replicating earth-side agriculture as
precisely as we
> can.
>
> Another link:
> http://advlifesupport.jsc.nasa.gov/crops/projects.html
>
> Florida State University's SABRE program is also doing space
agriculture