discussion about artificial lighting for space colonies

> On Jul 24, 2015, at 10:06 AM, Christopher Davidson cdmitridavidson@gmail.com [spacesettlers] wrote:
>
> I've always assumed that power would be easily obtainable via solar panels -- at least in the long run.

The issue is how much. For Kalpana One we use body mounted solar cells which gives you a maximum power level as a function of solar array efficiency. The numbers we came up with ended out with a somewhat low population density because we were power limited.

> Are you thinking of space settlements in the near term -- before we are able to mine asteroids or the moon?
>
> CD
>
> On Fri, Jul 24, 2015 at 9:56 AM, Al Globus alglobus@... [spacesettlers] > wrote:
>
> One thing to keep in mind when using artificial light for agriculture is that power may very well become the limiting factor on population size.
>
>> On Jul 14, 2015, at 3:42 AM, stephen.covey@... [spacesettlers] > wrote:
>>
>> Please check out my blog post on the topic of space colony lighting:
>>
>> Ramblings on the Future of Humanity: Lighting our Space Habitats
>>
>> 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...
>> View onramblingsonthefuture...
>> Preview by Yahoo
>>
>>
>> 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.).
>>
>
> --
>
> Christopher Davidson
> cdmitridavidson@...
>

cdmitridavidson@...
[spacesettlers] <
spacesettlers@...m
> wrote:
I've always assumed that power would be easily obtainable via solar panels -- at least in the long run.
The issue is how much. For Kalpana One we use body mounted solar cells which gives you a maximum power level as a function of solar array efficiency. The numbers we came up with ended out with a somewhat low population density because we were power limited.
Are you thinking of space settlements in the near term -- before we are able to mine asteroids or the moon?
CD

On Fri, Jul 24, 2015 at 9:56 AM, Al Globus

alglobus@...

[spacesettlers]

<
spacesettlers@yahoogroups.com
>

One thing to keep in mind when using artificial light for agriculture is that power may very well become the limiting factor on population size.
On Jul 14, 2015, at 3:42 AM,

stephen.covey@...

[spacesettlers] <
spacesettlers@yahoogroups.com
> wrote:
Please check out my blog post on the topic of space colony lighting:
Ramblings on the Future of Humanity: Lighting our Space Habitats
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...
View on

ramblingsonthefuture...
Preview by Yahoo

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.).

Christopher Davidson
cdmitridavidson@...