Life Support
  Air, Water, and Nutrition
  Waste Management
  Mental Health
  Suits
  Radiation and Zero-G

Habitat On Mars
  Power
  Structure
  Daily Routine

One Person, One Day, in Space*

Inputs 1.4 pounds of food (dry weight) 7-9 pounds of water 2 pounds of oxygen

Outputs 3.3 pounds of urine 4.0 pounds of metabolic water 2.2 pounds of carbon dioxide 0.4 pounds of solid waste

We must provide the input and recycle the output to create more input.

Life support systems, for use both in space and on Mars, can be designed similarly. Everything the astronauts will need must be sent with them, as space is devoid of resources and Mars, at this point, cannot be relied upon to provide any useful resource. To get an idea of the magnitude of this task, look at the figures - per person per day. Multiply that by the number of astronauts on the crew and the number of days in the mission and whopping numbers appear everywhere . So arise the governing principles in designing life support: Reduce, Reuse, Recycle.

* Shipman, Harry L. (1989). Humans in Space. New York: Plenum Press.