Artificial sunlight?

In several experiments conducted by NASA and by the Russians plants
were grown indoors using an artificial light. What type of light was
used that produces light on the same wave lengths as the suns does?


Christopher
+++++++++++++++++++++++++
"Kites rise highest against
the wind - not with it."
Winston Churchill

(Christopher) wrote in message ...
In several experiments conducted by NASA and by the Russians plants
were grown indoors using an artificial light. What type of light was
used that produces light on the same wave lengths as the suns does?

Are you sure the lights produced the same wave length as the sun?

On TV documentaries, various forms of fluorescent lights seem to be
the popular light sources for hydroponics experiments. AFAIK, those
tend to be UV-heavy and a bit 'bluish' compared to natural sunlight.

(Christopher) wrote in message ...
In several experiments conducted by NASA and by the Russians plants
were grown indoors using an artificial light. What type of light was
used that produces light on the same wave lengths as the suns does?

Are you sure the lights produced the same wave length as the sun?

On TV documentaries, various forms of fluorescent lights seem to be
the popular light sources for hydroponics experiments. AFAIK, those
tend to be UV-heavy and a bit 'bluish' compared to natural sunlight.

Christopher wrote:
In several experiments conducted by NASA and by the Russians plants
were grown indoors using an artificial light. What type of light was
used that produces light on the same wave lengths as the suns does?

Standard lights used for lighting homes/offices/stadia work just fine.
The basic problem is that they emit relatively little light.

Sunlight is around a kilowatt a square meter (in most latitudes).
One 12W compact fluorescent light generates as much light as a window
around 5-6cm square.
I'm currently growing some water plants under 2*12W CF lights, probably
producing around 2000 lumens.
Over maybe .1 square meter, for around a sixth of sunlights intensity.

However, plants generally don't exploit all sunlight.
From my (sparse) knowledge of biology, photosynthesis tops out at some
fraction of the brightest sunlight.

Christopher wrote:
In several experiments conducted by NASA and by the Russians plants
were grown indoors using an artificial light. What type of light was
used that produces light on the same wave lengths as the suns does?

Standard lights used for lighting homes/offices/stadia work just fine.
The basic problem is that they emit relatively little light.

Sunlight is around a kilowatt a square meter (in most latitudes).
One 12W compact fluorescent light generates as much light as a window
around 5-6cm square.
I'm currently growing some water plants under 2*12W CF lights, probably
producing around 2000 lumens.
Over maybe .1 square meter, for around a sixth of sunlights intensity.

However, plants generally don't exploit all sunlight.
From my (sparse) knowledge of biology, photosynthesis tops out at some
fraction of the brightest sunlight.

Christopher wrote:
On Mon, 15 Dec 2003 19:26:48 GMT, Ian Stirling
wrote:

Christopher wrote:
In several experiments conducted by NASA and by the Russians plants
were grown indoors using an artificial light. What type of light was
used that produces light on the same wave lengths as the suns does?

Standard lights used for lighting homes/offices/stadia work just fine.
The basic problem is that they emit relatively little light.

Sunlight is around a kilowatt a square meter (in most latitudes).
One 12W compact fluorescent light generates as much light as a window
around 5-6cm square.
I'm currently growing some water plants under 2*12W CF lights, probably
producing around 2000 lumens.
Over maybe .1 square meter, for around a sixth of sunlights intensity.

However, plants generally don't exploit all sunlight.
From my (sparse) knowledge of biology, photosynthesis tops out at some
fraction of the brightest sunlight.

Right, thanks for that, I only asked as there is a longish thread in
sci.space.policy regarding this type of space activity.


A very, very handy lighting FAQ I found is:

Radiometry and photometry in astronomy
http://home.tiscali.se/pausch/comp/radfaq.html

This has basic numbers for everything from the brightness of the whole sky
when the sun is 20 degrees below the horizon, to what a lumen is.

Christopher wrote:
On Mon, 15 Dec 2003 19:26:48 GMT, Ian Stirling
wrote:

Christopher wrote:
In several experiments conducted by NASA and by the Russians plants
were grown indoors using an artificial light. What type of light was
used that produces light on the same wave lengths as the suns does?

Standard lights used for lighting homes/offices/stadia work just fine.
The basic problem is that they emit relatively little light.

Sunlight is around a kilowatt a square meter (in most latitudes).
One 12W compact fluorescent light generates as much light as a window
around 5-6cm square.
I'm currently growing some water plants under 2*12W CF lights, probably
producing around 2000 lumens.
Over maybe .1 square meter, for around a sixth of sunlights intensity.

However, plants generally don't exploit all sunlight.
From my (sparse) knowledge of biology, photosynthesis tops out at some
fraction of the brightest sunlight.

Right, thanks for that, I only asked as there is a longish thread in
sci.space.policy regarding this type of space activity.


A very, very handy lighting FAQ I found is:

Radiometry and photometry in astronomy
http://home.tiscali.se/pausch/comp/radfaq.html

This has basic numbers for everything from the brightness of the whole sky
when the sun is 20 degrees below the horizon, to what a lumen is.

Mike Miller wrote:
(Christopher) wrote in message ...
In several experiments conducted by NASA and by the Russians plants
were grown indoors using an artificial light. What type of light was
used that produces light on the same wave lengths as the suns does?

Are you sure the lights produced the same wave length as the sun?

On TV documentaries, various forms of fluorescent lights seem to be
the popular light sources for hydroponics experiments. AFAIK, those
tend to be UV-heavy and a bit 'bluish' compared to natural sunlight.

there are also high pressure sodiums and others. there may well be a
section in your local garden store stocking 'growlights'. plants do
not make use of all spectrum of sun, so using something that imitated
sun wold be wasteful. much better to give plants the spectrum where
they would use 95%+ of it.

--
Sander

+++ Out of cheese error +++

Mike Miller wrote:
(Christopher) wrote in message ...
In several experiments conducted by NASA and by the Russians plants
were grown indoors using an artificial light. What type of light was
used that produces light on the same wave lengths as the suns does?

Are you sure the lights produced the same wave length as the sun?

On TV documentaries, various forms of fluorescent lights seem to be
the popular light sources for hydroponics experiments. AFAIK, those
tend to be UV-heavy and a bit 'bluish' compared to natural sunlight.

there are also high pressure sodiums and others. there may well be a
section in your local garden store stocking 'growlights'. plants do
not make use of all spectrum of sun, so using something that imitated
sun wold be wasteful. much better to give plants the spectrum where
they would use 95%+ of it.

--
Sander

+++ Out of cheese error +++

william mook wrote:

The absorption maxima of chlorophyll a are 430 and 662 nm, that of
chlorophyll b are at 453 and 642 nm.


http://www.biologie.uni-hamburg.de/b-online/e24/3.htm

So, solid state LEDs that emit around these frequencies would be very
efficient at growing plants.

Looking at the spectrum of the sun ...

http://zebu.uoregon.edu/~js/glossary/planck_curve.html

(there are 10 angrstoms per nm)

and multiplying the chlorophyl response curve by the solar spectrum,
we can see that its possible to grow plants with the right colors of
light at about 5% of the energy of full spectrum sunlight.

This suggests that dyes, or high-efficiency solar cells powering high
efficiency LEDs of the right colors might be capable of growing more
food per unit area than natural sunlight.

It would appear that using PV cells getting ~ 15 - 20% of energy from
sunlight would allow one to build 3-5 high greenhouses that were much
more space efficent (which is not a trivial concern) than ones directly
using sunlight.

So to solve teh worlds food supply problems for a long time one would then
just need a cheap way to de-orbit food.

A concentrating mirror can focus sunlight onto an appropriate
apparatus that simultaneously produces electricity and increases
growing efficiency and area underneath the mirrors. The electricity
can be used in part to take nitrogen and water vapor in the air and
combine it to produce ammonia based fertilizers from sunlight and air.

But there are not just plants that have nitrogen fixing symbiotic bacteria
(which includes soybeans, and other beans / peas which are likely to be
in the crops list) and also many free-living bacteria do this. So is a
separate process other than reprocessing results of biological processes.

Also, many photosynthesising cyanobacteria are also nitrifying.

--
Sander

+++ Out of cheese error +++