Photosynthesis—the process plants use to turn light into sugar—produces detectable signs of life at a global scale, she explained.
Photosynthesis on Earth is responsible for atmospheric oxygen and ozone. The same may be true on other planets, she said.
"That oxygen and ozone on Earth can be seen from space. It can be seen from a very great distance, so it's a good thing to go after [when searching for extraterrestrial life]," she said.
"It's not only the fact that we think photosynthesis is highly likely if there's surface life, but also the signs of photosynthesis are relatively easy to detect," Meadows said.
The new research, the authors added, will guide the development of future telescopes designed to search for life on other planets.
NASA's Kepler spacecraft, scheduled to launch in October 2008, will be able to detect Earth-size planets in habitable zones around distant stars. This will help scientists understand whether these types of planets are common.
(See National Geographic magazine's "Search for Other Earths.")
Scientists hope future space telescopes, such as NASA's proposed Terrestrial Planet Finder and the European Space Agency's Darwin, will be able to find and study nearby extrasolar planets.
The telescopes will allow scientists to determine what a given planet's surface is made of and what chemicals are in its atmosphere.
That information, combined with data on the wavelengths of light from the parent star, will allow scientists to determine what colors of light the planet's plants most likely use for photosynthesis—and what colors they reflect.
"That's what this research is relevant to," Meadows said.
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