After decades spent scanning the heavens for signs of life elsewhere in the cosmos, astronomer Jill Tarter is stepping back, and letting a colleague take charge of the quest.

Tarter, whose alien-seeking efforts inspired the Hollywood film "Contact," announced Tuesday that she is stepping down as director of the nonprofit SETI Institute to focus on raising money to keep the effort going.

The institute, its name an acronym for "search for extraterrestrial intelligence," scours space for radio waves or other signals.

With help from a TED Prize (for technology, entertainment and design) that she won in 2009, a setilive.org website launched in February as a venue for amateurs to scrutinize patches of radio spectrum looking for anomalies worth investigating further.

"We are trying to get citizen scientists to help us look through frequencies crowded with our own communications to filter out our own and see if anything is left over that might be coming from someone else's technology," Tarter said.

More than 58,000 people have signed up website and millions of signals have been scrutinizes and classified, according to counters at the website.

SETI was testing improvements to setilive.org that would let professional scientists follow up on people's observations in real time, chasing signals while trails are fresh and telescopes still on targets.

"This is the first time anybody has tried to do this citizen science work in real time," Tarter said. "It is a real challenge."

The website emphasizes sifting through radio bands crowded with human-generated transmissions, based on reasoning that aliens might have noticed the chatter and thought to send messages back along the same channels.

Tarter's career will be celebrated at the second annual SETIcon gathering of scientists, artists, and entertainers in the heart of Silicon Valley the weekend of June 22.

Speakers at a gala event planned for Tarter are to include astronaut Mae Jemison; "Star Trek: Voyager" television series actor Robert Picardo; and the author of the Drake equation for estimating the number of detectable alien civilizations in the Milky Way.

Tarter, 68, joined the NASA SETI program in the 1970s as part of a small team of researchers developing ways to look for alien signals in radio waves.

She has championed the effort at the SETI Institute since the plug was pulled on the NASA program in 1993.

Tarter is encouraged by word that NASA's Kepler telescope discovered thousands of new planetary systems.

"It is exciting after all this time to know where to look," Tarter told AFP.

"We are all holding our breath for Earth 2.0, an Earthlike planet," she continued. "Everyone has this feeling it is just around the corner; you can almost taste it."

Planet hunters will be key presenters at SETIcon, details of which are available online at seticon.com.

Tickets to the event range from $65 for a keynote brunch to $1,000 for a "Cosmic VIP" pass promising prime access to all aspects of the three-day gathering. The event raises funds for SETI's work.

Gerry Harp will take over as director of SETI Institute.