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Air and Water
Investigation: How can humans maintain enough clean water and breathable air during an extended space mission?

The average person can live about three days without water. Without air, permanent brain damage can occur within three minutes. The vast resources of Earth naturally provide and recycle carbon dioxide, oxygen and water. It is extremely challenging to provide breathable air and drinkable water in the International Space Station or the space shuttles.

Drawing of water cycle

NASA scientists apply their understanding of Earth's water cycle to developing solutions for providing quality air and water on Earth and in space habitats. Image Credit: NASA

NASA has been developing regenerative life support systems. These systems use plants or algae along with physical and chemical processes. The green plants produce food, convert carbon dioxide to oxygen through photosynthesis, produce drinkable water through evapotranspiration, and recycle organic wastes.

To understand the life support systems developed by NASA, students learn how carbon dioxide, oxygen and water are recycled on Earth. Students learn the basics of the carbon cycle, photosynthesis, respiration and the water cycle. They apply that understanding to the problem.

Assessment Task
Students design a system to maintain clean water and breathable air for six researchers in a habitat on the moon or Mars and explain why it should be successful.
Download Formative Assessment Rubric (PDF)

Content Area Resources
The following Web resources are provided to assist you in facilitating inquiry-based learning and to address the investigative questions for this unit. Some of the resources are on NASA Web sites and others are not. Web sites that are external to www.nasa.gov are indicated with an arrow. Some items may be in PDF format. Recommended grade levels are indicated whenever they are specified in the resource.

Background Information on the Carbon Cycle
Earth Observatory: Carbon Cycle (Teacher Resource)  →

Explanation of the Water Cycle by the U.S. Geological Survey
The Water Cycle (Teacher Resource)  →
USGS Water Cycle Poster (Teacher Resource)  →

NASA Water and Energy Cycle
NASA Energy and Water Cycle Study (Teacher Resource)  →
Meet Molecule Max (Animation) (5-8 and 9-12)  →

Introduction to Concepts of Watersheds
Watershed Ecology (Teacher Resource) (9-12)  →

Support Systems for the International Space Station
These short articles descibe support systems used for the International Space Station, or ISS.
Sci-fi Life Support (9-12) (Audio version available on the Web site.)   →
Water on the Space Station (9-12) (Audio version available on the Web site.)  →
Beneficial Bacteria (10-12)
Plumbing the Space Station (10-12) (Audio version available on the Web site.)  →
New NASA System Will Help Space Station Crews Breathe Easier (10-12)

Information about Recycling Air and Water on the ISS
The Science of Space Recycling (Teacher Resource with Video) (4-8 and 9-12)
Cleaning Water Activity (3-5)
Where Would a Space Explorer Find Water and Oxygen? (Teacher Resource and Student Activity) (5-8 and 9-12)  →