For three decades, Jill Tarter has been the person most likely to be the first to know if we make contact with E.T. -- the one who will sound the alarm that We Are Not Alone.

Over the decades she has brooked few distractions from the quest to look for radio signals from aliens. When a reporter (OK, it was me) described her blond hair tied with a pink ribbon into a ponytail, she cut her hair short.

When researchers at the SETI Institute got a new radio telescope for their search -- the Allen Array, at the University of California's Hat Creek Observatory in Northern California -- she got a pilot's license so she could make the trip from her Berkeley home in one hour instead of six.

Jodie Foster's performance in the movie "Contact" was largely based on time she spent with Tarter.

Now Tarter, 68, is stepping away from the radio telescope, retiring from her post as the director of the Center for SETI Research at the SETI Institute in Mountain View. SETI, of course, refers to the search for intelligent life in the universe. "The SETI Institute has a good pension plan -- we're grown-ups," she said.

She never did get to deliver the news that we have company. But this, she said, is not disappointing. What would be disappointing is if humans were not able to search for their neighbors at all.

It was in the 1970s while she was pursuing a Ph.D. in astronomy at the University of California, Berkeley, and raising a daughter that she first heard of SETI: the idea that lonely species could bridge the voids between stars with radio waves. She fell in love with it after reading a NASA report on the subject edited by Barney Oliver, the former head of research at Hewlett-Packard. Reassuringly, Oliver was a crusty gear head who had made himself and others rich, not the sort of man given to romantic fantasies. Hard-boiled, you might say.

Tarter said the high point of her life was Columbus Day of 1992, when on the 500th anniversary of the great explorer's arrival in the Americas NASA launched its survey of the 1,000 nearest stars in its search for alien radio signals. Tarter, then a researcher at NASA's Ames Research Center in Mountain View, Calif., was in charge of it. "I felt so proud," she recalled.

A year later it was over, canceled at the behest of Sen. Richard Bryan of Nevada, who was skittish about "little green men."

With help from Silicon Valley friends, Tarter and her colleagues took the search private and, over time, expanded it farther out in space, to stars identified by the Kepler spacecraft as having planets.

Last year, however, the recession left the University of California with no money to operate Hat Creek Observatory, and the Allen Array had to be shut down, a moment that Tarter called the low point of her career. "To have built that beautiful instrument and then have to turn it off, that hurt," she said.

The Allen Array is now back on the cosmic search, thanks to a deal with the Air Force. But to Tarter, it was a wake-up call: SETI needs a permanent endowment. "It's on my to-do list," she said.

Once upon a time it was a crazy, romantic idea, perhaps nothing better than wishful thinking. It still is, but it makes us feel bigger and more grown-up just to try.