Exploratour: NASA's Exploration for Life

Autumn Foliage
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Image courtesy of Corel Photography

You can read about Photosynthesis here

Photosynthesis is the name of the process by which autotrophs (self-feeders) convert water, carbon dioxide, and solar energy into sugars and oxygen. If it weren't for the photosynthetic activity of early bacteria, Earth's atmosphere would still be without oxygen and the appearance of oxygen-dependent animals, including humans, would never have occurred!

This means one way to detect life's activity on a distant planet is to look for significant levels of oxygen.

Other types of bacterial life break down large molecules for energy and create methane or sulfur as a waste product, so scientists would test the levels of these molecules as well.

Sophisticated plant life also goes through the process of respiration, where oxygen and carbohydrates are converted into carbon dioxide. One way scientists measure increased activity by the plant kingdom on Earth is to test levels of carbon dioxide in the air.

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