Artificial lighting, huh?

On Oct 30, 2007, at 15:38 UTC, Ron wrote:

> CRI is important to plants with regards to the quality of
> photosynthetic radiation, meaning mostly red and blue light. It is
> important that the artificial light created has the right balance of
> these hues. But, other wavelengths also play an lesser, but equally
> important role in plant health.

I doubt other wavelengths are "equally important" -- in fact I suspect
they're not important at all, for most plant species. The main effect
of light on plants is to provide energy to chlorophyll, which absorbs
certain wavelengths. Other wavelengths are converted to heat, which a
space colony needs to reject -- and heat rejection is one of the
biggest costs in most colony designs. So it's very important (to the
colony) to provide the plants with only the wavelengths and amounts of
light they can effectively use.

> Humans seem to thrive better in natural sunlight than they do in
> artificial light. This is a rather complex and not well understood
> subject.

True, though as you say, artificial lights these days can come very
close to matching the natural spectrum.

> But, will installing artificial light cost more than
> installing windows in the habitat shell? Probably.

I really, really doubt that. Getting your light through windows costs
a lot more than just the cost of the windows (and mirrors and other
structures needed to let the light in but keep your colonists from
rapid, unpleasant deaths due to radiation poisoning). It imposes
severe constraints on the entire design of your habitat. Most
importantly, it pretty much prohibits a multi-level design, which is by
far the most efficient way to make use of your pressurized,
radiation-shielded rotating volume.

(Mike will point out the 1977 study, but they do not appear to have
looked into this issue in very much depth, and in addition, artificial
light technology has improved a lot in 30 years.)

> Why is
> it logical and cost effective to construct a habitat to be more
> articial than the environment to which we hymans are adapted to?

That's an odd question. Why wouldn't it be? Is there some cosmic
elegance principle that you feel is violated when it turns out that
designs using artificial light are more cost-effective than ones using
natural light?

> If it is reasonable to deviate from the environmental norms to which
> we are use to and doing so does us no harm, than it should be
> considered. If there is no good reason to do so or if it might prove
> to be harmful, then we mustn't make the change.

That's certainly a sensible position.

Best,
- Joe

Joe Strout
Inspiring Applications, Inc.
http://www.InspiringApps.com