If you discount numerous UFO and alien-abduction stories reported since the late 1940s-some fascinating, but all without a jot of proof-there isn't much reason to suggest that intelligent species exist beyond the Earth. On the other hand, the universe is vast; intelligent civilizations may be widely separated among the less common, Sun-like stars.
The idea of communicating with ETs began in earnest during the 1960s. Researcher Frank Drake, considered the father of SETI astronomy (SETI, short for Search for Extraterrestrial Intelligence), hosted the first SETI astronomy conference in the Appalachian Mountains of West Virginia in 1961.
Around the time of the SETI conference, Drake used the big 26-meter diameter radio telescope of the Green Bank, W.Va., observatory to study two Sunlike star systems: Epsilon Eridani and Tau Ceti.
I asked Dr. Drake about how he got the idea to use radio to eavesdrop on aliens.
Following a suggestion in 1959 by Cornell University physicists Giuseppe Cocconi and Philip Morrison, Drake said he proposed listening to two nearby stars at the 1,420 megahertz frequency (1 megahertz is one million cycles per second), the so-called magic frequency of the 21-cm line of neutral hydrogen. This location on the radio dial is now considered the universe's "waterhole"-the radio frequency at which intelligent species might consider a common place to talk and listen, much like the waterholes of Africa where animals come to drink (and humans came to hunt!).
Since hydrogen is the most abundant chemical element in the universe, Cocconi and Morrison reasoned aliens might transmit radio messages across the void in an effort to establish long-distance communication between the worlds.
Drake's ad hoc effort of listening for ET radio broadcasts was called Project Ozma.
"We named it after Frank Baum's Wizard of Oz's far away realm," Drake told me. "Needless to say, no alien broadcasts were ever detected over the months we listened to the deep sky."
Since Project Ozma, SETI experiments have continued in the U.S. and elsewhere-also with no results. SETI research remains a hard sell, especially to elected officials doling out public funds.
Public funding for the search for "little green men" has become the third rail of astronomy-witness NASA's short-lived HRMS or High Resolution Microwave Survey Targeted Search Program of 1992-93. HRMS was ridiculed by so many U.S. Congress members that they ended up canceling the effort, just a year after it began, with considerable media-supported flourish.
In the aftermath of the HRMS fiasco, organizations such as the SETI League, and the privately funded SETI Institute of Mountain View, Calif., continue hardcore scientific SETI research . The SETI field has also branched out to include optical SETI, the search for visible alien transmissions-such as laser beams-that might, it's theorized, be a better means of communications over vast distances than radio.
With the SETI, the question remains: do we really want to contact other intelligent species? And will they be friendly or hostile?
What's in the Sky: This week, look north near the constellation Cassiopiea. With binoculars, you can see the open star cluster Stock 2. Draw lines from Miram in Pegasus up to Eps Cas in Cassiopeia to Ruchbah and back to Miram. Object is about 10 -12 above the horizon. Many deep space objects here. See clusters NGCs 884 and 869, Mel 13, and Cr 33.
Lou Varricchio, M.Sc., is a former senior science writer at the NASA Ames Researcg Center. He is currently NASA-JPL Solar System Ambassador in Vermont. You can follow him on Facebook.