WASHINGTON — A Russian billionaire announced July 20 he is pledging $100 million to a private effort to search for signals from extraterrestrial civilizations, a project that will be chaired by a former director of NASA’s Ames Research Center.

Yuri Milner, a Russian investor with an estimated net worth of more than $3 billion, announced the ten-year “Breakthrough Listen” project at a press conference in London that featured physicist Stephen Hawking and astronomer Frank Drake, who started the modern era of the search for extraterrestrial intelligence (SETI) in 1961.

The funding will be used, in part, to pay for time on two radio telescopes, the Robert C. Byrd Green Bank Telescope in West Virginia and the Parkes Telescope in Australia. The project will also use a telescope at Lick Observatory in California to search for laser pulses that might be evidence of extraterrestrial civilizations. In addition, the project plans to develop advanced detectors to search a wider range of frequencies at greater sensitivities.

Breakthrough Listen is funded by Milner’s Breakthrough Prize Foundation, whose chairman is Pete Worden, the former director of NASA’s Ames Research Center. Worden left Ames at the end of March after nearly nine years of running the center in California’s Silicon Valley. At the time, he said he would “likely focus on the educational area” after leaving NASA but offered no specific career plans.

In a teleconference with reporters July 20, Worden said the offer to chair the foundation and its SETI effort lured him to leave the space agency. “It was this opportunity that enticed me away from NASA,” he said. “The opportunity to move forward extremely quickly with the world’s best scientists and instruments is very exciting.”

SETI projects have relied primarily on private funding after Congress canceled a NASA SETI effort called the High Resolution Microwave Survey in 1993 after just one year of operations. What sets Breakthrough Listen apart, say scientists involved in SETI, is the size of the donation and Milner’s ten-year commitment to the project.

“For once, after all of these years of being guest observers and poverty stricken, we will finally have stable funding so that we can plan from one year to the next,” said Drake, professor emeritus of astronomy and astrophysics at the University of California Santa Cruz. “We can hire very talented people to carry out the work, and we will have the most powerful search, and enduring search, that has ever been launched.”

While Breakthrough Listen is working with Drake and a team at the University of California Berkeley that has been involved in SETI projects for many years, notably absent from the announcement was the SETI Institute, the Mountain View, California-based organization that has organized and raised money for many SETI efforts since the end of NASA’s program.

Worden said that that the Breakthrough Prize Foundation may later cooperate with the SETI Institute. “Certainly in the future, we’re planning on discussions with the SETI Institute and the Allen Telescope Array and possible roles they could perform,” he said. The Allen Telescope Array is a cluster of small radio dishes operated by the SETI Institute in northern California, whose development was funded by Microsoft co-founder Paul Allen.

“The funding announced today does not go to the SETI Institute, but we are working with the Breakthrough Prize Foundation on other projects,” the institute said in a July 20 statement. It did not elaborate on what those other projects are.

Although Milner’s commitment to Breakthrough Listen is for ten years, he said he was open to extending it should the project not detect any signals. “We, as human beings, have a responsibility to continue this project,” he said. “If we don’t find anything, I think we should keep going until such time that we have a reasonable chance to draw some conclusions.”

In addition to Breakthrough Listen, the foundation is funding a smaller project, Breakthrough Message, offering $1 million in prizes for the best messages representing humanity that could be transmitted into the universe. The foundation, though, has no plans to transmit the winning messages.

Worden hinted that the Breakthrough Prize Foundation might also support additional projects. “Stay tuned, we have a lot of ideas and plans for the future,” he said. “This is such an incredible opportunity I pinch myself every day when I get up and say I get to work on this. It’s way cool.”