In Search for Alien Life, Researchers Enlist Human Minds On a chilly morning last week, Jill Tarter sat in a makeshift corner office facing the Allen Telescope Array, pondering a set of parallel lines that striped a window in her MacBook.
Dr. Tarter directs the Center for SETI Research — SETI is the search for extraterrestrial intelligence — and the 42 antennas that sit outside her window are once again sampling radio emissions from a patch of sky that offers a window into one of the spiral arms of our galaxy. Shuttered for more than a year by budget problems, the array was turned back on in December to continue its search. Now, the searchers have another reason for optimism.
With new Web-based software called SETILive, an army of independent citizen-scientists are being enlisted to help with the hunt for unusual signals. The software, which can be found at setilive.org, was designed by Zooniverse, a team of programmers and scientists who have created Web-based systems to enable citizen participation in research in fields like astronomy and marine biology. SETILive was switched on late last month.
In two weeks, more than 40,000 volunteers have signed up, and more than one million radio samples have been analyzed. (Another Zooniverse project, Galaxy Zoo, has enabled more than 600,000 amateur astronomers to help with classifying an immense number of deep-sky objects since 2007.)
Thanks to the remarkable revelations of the Kepler satellite mission, the searchers have a target list. Kepler has revealed thousands of planets relatively close to our solar system. Now, rather than sweeping the entire sky, the array of 42 antennas, spread over the countryside in the mountain valley here in Northern California, dart electronically from target to target, capturing snippets of what the watchers hope might be evidence of alien life.
Dr. Tarter, a 68-year-old astronomer, said the use of volunteers was an experiment. She is hoping that the SETI researchers can use human pattern recognition to fine-tune software algorithms that in the past have been used to look for tantalizing signals hidden among fields of natural stellar radiation and human-made sources of interference.
Even a single cellphone can raise havoc with the sensitive antennas, which are supercooled and can scan a huge swath of the radio spectrum, from 1 to 10 gigahertz.
This is not the first time that SETI has looked to human volunteers. Over the past decade, the organization has used the Internet to weave together a virtual supercomputer called SETI@Home, analyzing roughly 160 terabytes of radio data collected by the radio telescope at Arecibo, P.R. More than six million volunteers have run the SETI@Home software on their desktop computers, and that project is now being extended to take advantage of the new information produced by the Kepler mission.
With SETILive, the researchers are hoping to add the power of the human mind to the scanning efforts. Projects in other fields have already proved the power of relatively untrained human participants. For example, Foldit, a project of University of Washington biochemists and computer scientists, developed a Web-based video game that treated protein-folding as a puzzle. The researchers were able to demonstrate that the game’s players, many of them high school students with little background in biology, could outperform the best protein-folding algorithms.
“We have software that finds narrow-band signals much better than your eye can,” Dr. Tarter said. “Basically what we’re doing with humans is to see how well they do. We are giving them marking tools and learning how they extract features.”
In the past, she said, a huge challenge for the SETI researchers has been that the researchers have had to contend with powerful interference sources at the sites of their radio observatories from both Earth-based radars and satellite communications. The Allen telescope site here in Hat Creek is relatively free from interference sources.
There is also, of course, the “drunk under the streetlight” effect. SETI researchers have devoted much of their resources to the electromagnetic spectrum from 1 to 10 gigahertz because it offers a relatively quiet window for observation from within the Earth’s atmosphere. If there were an alien civilization orbiting a nearby star, no one is really certain how they would choose to communicate with us. Radio or television broadcasts are a possibility, but so are powerful pulsed lasers and conceivably communications that employ some advanced phenomenon like quantum entanglement.
In the past decade, because of the falling cost of advanced optical electronics detectors, some experiments have begun to take place at optical frequencies as well, Dr. Tarter said. Soon, optical experiments will also begin to look in the infrared portion of the spectrum.
For the moment, however, SETILive is adding a new, and already occasionally unpredictable, dimension to the hunt for alien worlds.
Since there is no absolute certainty about what a communication from another civilization might look like, the researchers are having to put up with some of the eccentricities of their volunteers.
“People are expecting that every single thing they see is going to be a signal and so they’re drawing patterns in noise,” Dr. Tarter said. “I had someone send me a face the other day. Here’s a noise field, and he saw a face.”