The next generation of orbiting space telescopes is set to produce some astounding exoplanetary science over the next decade, adding onto the Kepler space telescope’s already impressive legacy. They include three powerful instruments that will heighten the ability to detect Earth-like planets and perhaps the signatures of living beings: the Transiting Exoplanet Survey Satellite (TESS), the James Webb Space Telescope (JWST), and the Exoplanet Characterization Observatory (EChO).
The whole issue about life on other worlds begs the question: What is life, and how would we recognize it? Certainly, living things are made of cells (or a cell) and share three critical processes that make them alive. They ingest energy, excrete waste energy, and pass on their genes through reproduction. But they also respond to their environments. They maintain homeostasis, or internal balance. They evolve and adapt. Some living things even have evolved to the point where they can walk and think about the universe that surrounds them. We are literally products of the universe. Most of the atoms and molecules in our bodies were created in the engines of stars, and the energy we receive that enables life comes from our star: the Sun.
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But life on other planets may be very different. We can imagine a glimpse of what it might be like even by looking at bizarre and different environments here on Earth. For one thing, the vast majority of life on our planet comes in the form of primitive bacteria, fungi, molds, and other squishy, incredibly tiny organisms. (Viruses are not considered alive because they require a host to perform the functions of “life” — which, for them, amounts to cannibalizing cells.)