Explainer: SETI: 50 years of searching for E.T.

  • Somewhere out there, alien civilizations might be communicating with each other. They might even be trying to contact us. In 1960, this reasoning compelled astronomer Frank Drake to point a radio telescope at the stars and listen for chatter. He didn't hear E.T. calling us, calling home, or calling anywhere else during his four-month-long experiment at the National Radio Astronomy Observatory in Green Bank, W.Va., but the effort officially kicked off what is known as SETI, the search for extraterrestrial intelligence. Click the "Next" label to check out highlights from the first 50 years of the search.

    — By John Roach, msnbc.com contributor

  • 1974: Earthlings send message to aliens

    By 1974, Drake and his colleagues still hadn't heard anything from ET, but they hadn't given up hope. Instead, they sent a message out to the aliens with the Arecibo radio telescope in Puerto Rico, the first deliberate message sent from Earth out to the stars. The message contained information about life-giving chemicals, DNA, a simple drawing of our solar system, and pictures of human beings and the Arecibo telescope. The string of 1's and 0's was sent to a group of about 300,000 stars in called the Great Cluster in Hercules, Messier 13, about 25,000 light years away.

  • 1977: The Wow Signal

    Courtesy of Jerry Ehman / Bigear

    Did E.T. make a prank call to Earth on Aug. 15, 1977? We may never know for sure, but astronomer Jerry Ehman was struck enough by a string of letters and numbers on a printout of radio data from the Big Ear Radio Observatory at Ohio State University to scribble "Wow!" in the margin. The extraordinary signal might have been E.T., or something else. Whatever it was, astronomers have been unable to find it again despite dozens of searches, leaving open the possibility that E.T. called but hung up after the first ring.

  • 1992-1993: NASA's brief search

    U.S. Senate Historical Office

    Exactly 500 years after Christopher Columbus arrived in the New World, NASA officially launched its SETI program, the High Resolution Microwave Survey. Experts called it the most ambitious and technologically advanced alien-search effort ever conducted, but after just a year of operation the program was squashed. Sen. Richard Bryan, D-Nev., shown here, led the effort to kill the program, telling the Senate that "millions have been spent and we have yet to bag a single little green fellow. Not a single Martian has said take me to your leader, and not a single flying saucer has applied for FAA approval."

  • 1995: Project Phoenix rises from ashes

    Image: Paraffin candles
    Seth Shostak / SETI Institute

    When NASA funding for alien searches ran dry, private enterprise picked up the pieces - including some of NASA's equipment - and launched Project Phoenix. The targeted search focused on about 1,000 stars thought most likely to harbor alien civilizations and was conducted at various radio astronomy observatories around the world. In this image, SETI Institute astronomer Seth Shostak looks for E.T.'s call on a computer bank at the Arecibo observatory in Puerto Rico.

  • 1999: SETI for the masses

    SETI @ Home / UC-Berkeley
    Five million Internet users have contributed more than 3 million years of processing time to the search for signals from extraterrestrial civilizations through the SETI @ Home screensaver program, shown here.

    Hundreds, then thousands, and ultimately millions of computer users around the world got in on the search for E.T. with the 1999 launch of SETI@home, a distributed computing project run at the University of California at Berkeley. The program enlists personal computers to sort through the mountains of SETI data, one chunk at a time, collected by the Arecibo radio telescope. The combined power of all the computers running the program essentially acts like a super duper supercomputer, but at a fraction of the cost.

  • 2007: Telescope array turned on

    For most of the past 50 years, SETI projects have required astronomers to wait in line for time on giant radio telescopes around the world. That changed in 2007 with the opening of the Allen Telescope Array, a constellation of 42 radio telescopes with 20-foot-wide dishes in the scrublands about 300 miles northeast of San Francisco. The array, privately financed by software billionaire Paul Allen and others, puts the search for E.T. front and center. The project is jointly run by the SETI Institute and the University of California at Berkley. In the coming decades the array may grow to 350 antennas, making it one of the most powerful radio telescopes in the world.

  • The future of SETI

    NASA
    An artist's interpretation of the Kepler observatory in space. Credit: NASA

    As of this writing, extraterrestrials remain elusive, assuming that they exist at all. Given that the search is only 50 years old, many astronomers see little reason to despair - things are just getting going. NASA recently lent a new hand to the search with its Kepler mission, a space telescope that is looking for Earthlike, habitable planets around thousands of stars in our Milky Way galaxy. Detection of these planets will help SETI scientists focus their efforts.

    Other ideas include a push to expand the search beyond just radio signals. Paul Davies, a physicist at Arizona State University and author of several popular science books, argues that messages from E.T. might even be floating around in the junk DNA of terrestrial organisms and that we should start searching decoded genomes for the biotech equivalent of a message in a bottle.

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