Could Aliens Be Sending Us Laser Signals?

Discovery’s Cosmic Ray:

Over a decade ago SETI pioneer Jill Tarter and I had a dinner discussion about the protocol procedures for announcing to the world the first detection of a signal broadcast from an extraterrestrial civilization.

I expressed relief that I would never have to worry about publicizing such a discovery from Hubble Space Telescope. “Hold on Ray,” Jill said, “you never know, Hubble might conceivably pick up a signal that other telescopes can’t detect.”

Oh, my worst nightmare! Imagine keeping that information under a news release embargo!

Now, some readers will scratch their heads at this because SETI has been popularized in the 1997 movie Contact where actress Jodie Foster “listens” for radio signals from E.T. with the huge radio telescope array near Socorro, New Mexico.

But another communication strategy that aliens might use instead of radio signals is to send brief and intense bursts of laser light across the galaxy – sort of like a signal lamp between two ships. Some space telescopes would be ideally suited to pluck out such a signal from the sky background.

Why laser beams instead of radio transmitters? A directed beam across interstellar space would be unmistakable from the stellar background and could penetrate thousands of light-years. With each pulse of energy a signal from a big enough laser optics system could appear 1 million times brighter that the transmitting planet’s parent star. The thought is that an alien society would use an agile laser-transmitter to “paint” nearby target sunlike stars with a “searchlight beam.”