Scientist Searches for Second Earth

Somewhere out there are worlds that can support life. Lisa Kaltenegger has a way to find them

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[Big Data will let us explore distant planets]

The existence of life is a crapshoot. You need a nice, solid hunk of planet you can plant your feet on. You need lots of water and other friendly chemistry, some of it forming a quilt of atmosphere to keep out the cold. And you need to be just the right distance from just the right star--not too close, not too far; not too hot, not too cold. A terrarium like that incubating for, say, a billion years, might have a fair chance of cooking up something living. Those just-right conditions don't occur often, which explains why it's been so hard to find life on the tiny handful of worlds we have even a remote chance of visiting: the moons and planets in our solar system. For a long time, scientists didn't know much about planets elsewhere, so the rest of the cosmos looked like a biological washout.

That has changed. In the past 15 years or so, astronomers have discovered more than 4,200 potential exoplanets--planets orbiting distant stars--and confirmed the existence of more than 1,050 of them. In a galaxy with 300 billion stars, there are surely untold billions of other planets out there. Is anyone home on any of them?

Few astronomers are approaching that question as creatively as Lisa Kaltenegger, 36, an exoplanet investigator who is a lecturer at Harvard University and leader of a research group at the Max Planck Institute for Astronomy, in Heidelberg, Germany. The focus of her work is not discovering exoplanets, most of which have been detected by the Kepler space telescope. Rather, she and her team are modeling them--hoovering up massive amounts of data from Kepler, the Hubble Space Telescope and various ground telescopes and processing it through computer models to determine which worlds could harbor life. These days, so-called Big Data is inescapable, from algorithms that predict what you'll buy to government surveillance. Now it seems Big Data may also be the key to finding extraterrestrial life.

Kaltenegger's model is a complex one, factoring in a planet's size, mass, composition and orbit--whether it is in the habitable zone around its star, where temperatures would remain hospitable and water would remain liquid. Just as important are the size, nature and temperature of the star, since ones like our sun have a very different profile from, for example, a red giant's or a white dwarf's. Kaltenegger even includes a dash of the fantastical. "What if you have more than one host star? What if you see Tatooine?" she asks, referring to the childhood home of Star Wars' Luke Skywalker.

All that is impressive but not groundbreaking. Where Kaltenegger shakes things up is in her use of data from the only planet in the universe that, by definition, cannot wear the exo prefix: Earth. Her models include data about Earth's meteorology, geology and volcanology, plus one other important feature: its history.

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