NASA is preparing the TESS observatory (Transiting Exoplanet Survey Satellite) to follow-up on the successes of the planet-hunting Kepler observatory by identifying nearby exoplanets that pass in front of, or "transit," their stars. A small sample of these worlds will be singled out for further scrutiny if they lie within the habitable zone of the parent star. The habitable zone is the distance from a star where temperatures on a world may allow liquid water to exist on the planetary surface.
Kepler showed us an incredible diversity among planetary systems, and that small planets like Earth greatly outnumber bloated Jupiter-class worlds. But the Kepler planets are typically over 1,000 light-years away, so understanding the environments of these worlds is technologically out of the question - at least for the foreseeable future.
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It is a reasonable prediction that the first transiting candidate planet to look for the chemical signature of life will be a world orbiting a nearby red dwarf star. There are about 90 red dwarfs within just 20 light-years of Earth, but only seven sun-like stars.