discussion about artificial lighting for space colonies

Ill have to admit, some of the facts youre posting are making me a bit more open to the artificial illumination option than Ive been up to now.

Regards,
Mike Combs

From: spacesettlers@yahoogroups.com [mailto:spacesettlers@yahoogroups.com]
Sent: Tuesday, July 14, 2015 5:43 AM
To: spacesettlers@yahoogroups.com
Subject: [spacesettlers] Re: discussion about artificial lighting for space colonies

Please check out my blog post on the topic of space colony lighting:
Ramblings on the Future of Humanity: Lighting our Space Habitats

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Ramblings on the Future of Humanity: Lighting our Spa...
In previous posts (Designing a Space Habitat and Farming in Space) Ive argued that we do not want to use natural sunlight to illuminate our habitat and gr...

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There are two key factors:
1) the lighting needed to efficiently grow crops is only about 72 PAR watts per square meter. That is, of course, NOT white light, but rather just the wavelengths that plants can efficiently use.
2) The white light that people need for normal illumination is normally far less bright than sunlight. Indeed, a brightly-lit store or office workspace is only about 1% as bright as direct sunlight. Normal "home" lighting levels are a fraction of that.

The only real complication is that for hybrid areas (parks and commons) we'll need a white light source (for human vision) that is also sufficiently bright (PAR) to grow plants (but we don't need them to grow rapidly) - and these are the only areas where your "15% of full sunlight" would apply, although 10% is likely more than adequate. Most plants can thrive in 5% of full sunlight applied 12 hours per day.

Yes, I believe our "farms" should be enclosed and optimized for plant growth (lighting wavelengths and timing, warmth, humidity, CO2), and largely kept separate from the open areas that should have more "normal" conditions (normal day/night cycles, comfortable temperatures and humidity, white light, etc.).

Posted by: stephen.covey@...