SETI Project Looked Skyward

Paul Horowitz ’65 speaks swiftly, his mouth struggling to keep pace while his mind zips along tirelessly and rapidly from one subject to the next. A leading figure in the Search for Extra-Terrestrial Intelligence (SETI) community and a professor of physics and electrical engineering at Harvard, he radiates quirky genius.

Though Horowitz’s interest in extraterrestrial life began in his undergraduate years, it wasn’t until 1983 that he was able to tangibly bring that interest back to Harvard.

Horowitz’s research began in the late 70s, when Frank Drake, the founder of modern SETI, helped Horowitz obtain funding to do SETI research in Puerto Rico. Not long after, Horowitz went to the West Coast, partially at the behest of NASA, and developed his own project: Suitcase SETI.

Suitcase SETI—or, as Horowitz referred to it in a speech before the NASA Sunnyvale Symposium, “Steamertrunk SETI”—is a portable spectrum analyzer designed specifically to search for SETI transmissions. It featured autocorrelation receivers that enabled it to monitor 131,000 channels for extraterrestrial signals—far more than had previously been possible with any one device.

After a test run of 250 stars at the Arecibo Observatory in Puerto Rico that turned up nothing, Horowitz brought Suitcase SETI back to Harvard, and in 1983, Project Sentinel was launched. Project Sentinel utilized an 84-foot steerable radio telescope equipped with a renovated Suitcase SETI, located at the Oak Ridge Observatory in Harvard, Mass.

In his speech before the NASA Sunnyvale Symposium, Horowitz noted that Project Sentinal had its drawbacks: it required the use of “a directed and precompensated beacon” and operated based on what have been termed “magic frequencies”—frequencies that humans calculate would likely be used by aliens trying to contact us. Such narrow search mechanisms limit the ability to search the sky, forcing Horowitz to ask: “How hard are these guys up there really going to work?”

But the shortcomings of Project Sentinel failed to deter the determined Horowitz and team. They followed up the project with Megachannel Extra-Terrestrial Assay (META) in 1985, and then with Billion-channel ExtraTerrestrial Assay (BETA) in 1995.

Both these projects required the construction of a more powerful spectrum analyzer than Suitcase SETI, so that more channels could be scanned. These searches covered most of the northern sky, but failed to receive any signals that were ever replicated.

All of these projects were funded by the Planetary Society, with META receiving a large financial boost from Steven Spielberg, who got involved with the project in the wake of his movie, “E.T.: The Extra-Terrestrial.”

In March 1999, the 84-foot radio telescope was badly damaged in a storm, and in 2007 it was torn down. The search, however, continues for Horowitz, who has moved on to optical SETI, using a 72-inch optical telescope for his current project.

“Nobody’s got anything as fancy as we have at Harvard: this is the cat’s meow in terms of optical SETI.”

While no verifiable contact has yet been made, either by radio or optical telescopes, for Horowitz and many others, the search continues, and continues to be worthwhile.

—Staff writer Joshua J. Kearney can be reached at kearney@fas.harvard.edu.