Lighting

Lighting is vital for a colony. A colony might have a limited number of windows, so lighting would be required permanantly. Plants in greenhouses might need to be lit artificially to supplement natural light. Rovers must have headlamps for driving at night or during dust storms.

Types of lighting

Incandescent

Most lightbulbs on Earth are incandescent. Fire and stars produce light via incandescence. In an incandescent light-bulb a metal filament (Usually tungsten, the only metal that can withstand the temperatures) is heated to around 3000C. A glass bulb is fitted around the filament and the air evacuated or replaced by an inert gas, because the filament would otherwise oxidize and burn. In most commercial installation incandescent light bulbs have been replaced by fluorescents, that are themselves being replaced by LEDs.

LED

LED are energy efficient, and produce little heat compared to incadescent, flourescent, and halogen bulbs.

Human response to light

Humans have two types of vision, color and low-light. Once the vision has adjusted to low light, the average human is able to function well in the light of the full moon, but without the ability to see in color.

Health

The proper wavelengths of light are needed by humans to produce Vitamin D.

Certain lights, emulating natural sunlight, are used to treat Seasonal Affective Disorder.

Uses

Illumination

The primary use of lighting is illumination of a settlement. A well-lit environment is vital for the morale and safety of the residents. See table bellow for standard lighting levels.

Agriculture

Many plants require more sunlight than is available on the martian surface. Dust storms can also obscure the sun for months at a time. Artificial lighting is needed to at least augment the natural light.

Interior grow rooms use artificial light for plant production. This technology was developed for the production of Cannabis in closed environments but is applicable to all indoor grown plants. The most common power used for these installations is 300-600 W/m2, or about one quarter to one half the power of full sunlight.

Lighting levels

Condition	Illumination		Power intensity
	ftcd	lux	W/m2 (W/ft2)
Sunlight	10000	107 527	1300 (120)
Full daylight	1000	10 752	130 (12)
Overcast day	100	1 075	13-18 (1,3-1,8)
Very dark day	10	107
Twilight	1	10,8
Deep twilight	0,1	1,1
Full Moon	0,01	0,11
Quarter moon	0,001	0,011
Starlight	0,0001	0,0011
Overcast night	0,00001	0,00011

The table below provides recommended light levels from the IESNA Lighting Handbook and LPD levels from the IECC 2015

ROOM TYPE	LIGHT LEVEL (FOOT CANDLES)	LIGHT LEVEL (LUX)	IECC 2015 LIGHTING POWER DENSITY Watts/m2 (WATTS PER SF)
Bedroom - Dormitory	20-30 FC	200-300 lux	(0.38)
Cafeteria - Eating	20-30 FC	200-300 lux	(0.65)
Classroom - General	30-50 FC	300-500 lux	(1.24)
Conference Room	30-50 FC	300-500 lux	1.23
Corridor	5-10 FC	50-100 lux	0.66
Exhibit Space	30-50 FC	300-500 lux	1.45
Gymnasium - Exercise / Workout	20-30 FC	200-300 lux	0.72
Gymnasium - Sports / Games	30-50 FC	300-500 lux	1.20
Kitchen / Food Prep	30-75 FC	300-750 lux	1.21
Laboratory (Classroom)	50-75 FC	500-750 lux	1.43
Laboratory (Professional)	75-120 FC	750-1200 lux	1.81
Library - Stacks	20-50 FC	200-500 lux	1.71
Library - Reading / Studying	30-50 FC	300-500 lux	1.06
Loading Dock	10-30 FC	100-300 lux	0.47
Lobby - Office/General	20-30 FC	200-300 lux	0.90
Locker Room	10-30 FC	100-300 lux	0.75
Lounge / Breakroom	10-30 FC	100-300 lux	0.73
Mechanical / Electrical Room	20-50 FC	200-500 lux	0.95
Office - Open	30-50 FC	300-500 lux	0.98
Office - Private / Closed	30-50 FC	300-500 lux	1.11
Parking - Interior	5-10 FC	50-100 lux	0.19
Restroom / Toilet	10-30 FC	100-300 lux	0.98
Retail Sales	20-50 FC	200-500 lux	1.59
Stairway	5-10 FC	50-100 lux	0.69
Storage Room - General	5-20 FC	50-200 lux	0.63
Workshop	30-75 FC	300-750 lux	1.59

Open Issues

• How much exposure time is needed for the skin to produce enough vitamin D?