This artist's illustration shows NASA's Kepler telescope as it will look from its vantage point in space. The telescope is designed to survey a region of the Milky Way.
NASA
Astronomers scanning for signs of intelligent life beyond Earth will soon have a new tool at their disposal -- NASA's Kepler telescope.
Though intended to find Earth-like worlds orbiting other stars, the telescope's data will be analyzed to determine if any of its targets cast unnaturally shaped shadows into Kepler's eye.
Scientists plan to fix Kepler's gaze at a section of the Milky Way galaxy to observe about 100,000 stars over the next four years or so. They are looking for tiny, regular changes in how much light is coming from the stars, relative to Kepler's view, which may be caused by a planet passing in front of its parent star.
The technique, in use for about a decade, has helped astronomers discover more than 300 large planets. Kepler is intended to hone in on smaller worlds, like Earth, that are well positioned around their parent stars for Earth-like life.
Kepler is designed to detect changes in a star's brightness as small as about 10 parts per million. In the process of collecting photons, however, the shape of any transiting objects would be revealed as well.
"We would presume that a transiting planet would be round," said Jill Tarter, director of the Center for SETI Research in Mountain View, Calif., and a member of the Kepler science team. "So what if the light curve had a different shape?"
The premise behind SETI, an acronym for Search for Extraterrestrial Intelligence, is that technologically advanced civilizations want to make their existence known to their less-capable kin (i.e. us) and go about it by producing signals that might be detected in the course of our routine scientific observations.
SETI searchers to date have analyzed radio waves, and more recently light pulses, for artificially produced patterns. The Kepler telescope, along with Europe's COROT planet-hunting probe, present SETI with another option: looking for alien-made structures that perturb their planet's passing light.
The objects could be things like lightweight solar sails or a kind of alien cell phone tower used for interstellar communications.
"It opens a new window for SETI," Luc Arnold, an astronomer with France’s Observatoire de Haute-Provence, told Discovery News.
Four years ago, Arnold published a paper in The Astrophysical Journal describing what the light curves of three alien objects might look like.
"We could imagine other kinds of shapes. There is no limit," Arnold said. "The aim of my paper was to show that non-spherical objects would be able to be detected from the light curve signatures."
"I'm hoping that with Kepler we will have a lot of data to look at," he added. "Maybe we will discover something interesting."
Kepler is scheduled to be launched March 5 on an unmanned Delta rocket from Cape Canaveral Air Force Station in Florida.
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