Joe Strout wrote:
In article ,
Ian Stirling wrote:

There are a couple of caveats.
Current crop plants need more than one wavelength to thrive.
If you just feed them one then the plants do not perform as well as they
might as they use the spectrum of light to deduce the crowding of the plant,
as obviously the solar spectrum can't change...

True, I was oversimplifying. Still, my basic point is that with
gas-discharge and solid-state lighting, we have great control over the
spectrum of the light we generate. We can generate light which is more
or less perfectly tuned to what our crops need. Compare this with
sunlight, which is about half unusable (most of it is infrared, which
plants simply don't use).
snip
This beats current solar cells/lights by a factor of several per unit
area.

Yes, I know, I'm not saying that artificial lighting is better than
natural lighting when natural lighting is available. My point is that,
when natural lighting is not available or practical for whatever reason,
you don't give up on the whole idea and conclude that crops can only be
grown on Mars or some such. Instead, you put in artificial lights, and
this is a perfectly reasonable thing to do.

Perhaps.

How much does your garden weigh.
With silver pumps,
And Cabbage Heads,
......

Basically I'm trying to debunk claims I hear bandied about, from Zubrin
and others, that growing crops under artificial light is thoroughly
impractical due to energy requirements. I believe that's a

Maybe also mass requirements too.
Solar cells can be quite heavy, as can lights, thermal radiators, hydroponic
systems, growing plants, pressure vessels, even atmospheres.

Considering only dried food, you can get down to under around 1Kg/day.

(recycling most water into water and O2, using metabolic water to makeup
losses)

A garden at the very least means that you need (over stuff yuu wouldn't
need) lights (meaning either extra solar panels, or mirrors) extra volume
so a larger pressure vessel, segmented enviromental system (plants and
humans don't want quite the same things), thermal radiators, ...

I don't think it's a clear win until you'r into 5 year missions.