Light Sources

When growing plants under artificial lights, fluorescence lamps are usually the lights of choice. Fluorescent lamps have a broad light spectrum, and provide a good light efficiency (lumen output to watt).

While I am sure it's possible to strobe fluorescent lamps, I do not know if the energy saved by strobing fluorescent lamps would be worthwhile. Besides fluorescent lamps are fragile, not the type of equipment desired in space or for extended space flight.

Incandescent lamps are too inefficient, low lumen output per watt consumed. In addition to the low efficiency, the light output of the incandescent is very much in the infrared and red portions of the spectrum.

My choice for lighting are superbright LED's. NASA has been growing plants under LED illumination for a number of years. While I have read reports of NASA's plant grow chambers using LED illumination, I could not find any hard data on the LED spectrum and lumen intensity used.

Average Lumen Per Watt for 3 Major Light Sources:

Edison Based Tungsten Lamp 14 Lumens Per watt
Fluorescent Lamps 72 Lumens Per watt
Super Bright LED 50-75 Lumens Per watt *

* Varies as to type and wavelength

We can see from the chart that LED illumination is an efficient light source comparable to fluorescent light illumination. With the added benefit of being, rugged, solid state and suitable for the rigors of space flight. I am sure that in the future, LED efficiency will improve.

Other superbright LEDs may be used instead of the LEDs outlined. If you use different LEDs, keep a record of the specific wavelength emitted by the LEDs and the voltage required. This is essential so that others can replicate your results if necessary. Also if the required voltage of the LED is different you can modify the circuit as required.

Back Page (Two Control Groups) | Next Page (Inverse-Square Law)

Back to Top